0001437749-21-006074 | 10-K | XBRL Viewer | Acelrx Pharmaceuticals INC

Basis of Presentation and Significant Accounting Policies [Text Block]

1. Organization and Summary of Significant Accounting Policies

The Company

AcelRx Pharmaceuticals, Inc., or the Company or AcelRx, was incorporated in Delaware on July 13, 2005 as SuRx, Inc., and in January 2006, the Company changed its name to AcelRx Pharmaceuticals, Inc. The Company’s operations are based in Redwood City, California.

AcelRx is a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for use in medically supervised settings. DSUVIA®(known as DZUVEO^TM in Europe) and Zalviso® areboth focused on the treatment of acute pain, and each utilize sufentanil, delivered via a non-invasive route of sublingual administration, exclusively for use in medically supervised settings. On November 2, 2018, the U.S. Food and Drug Administration, or FDA, approved DSUVIA for use in adults in a certified medically supervised healthcare setting, such as hospitals, surgical centers, and emergency departments, for the management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. The commercial launch of DSUVIA in the United States occurred in the first quarter of 2019. In June 2018, the European Commission, or EC, granted marketing approval of DZUVEO for the treatment of patients with moderate-to-severe acute pain in medically monitored settings. AcelRx is further developing a distribution capability and commercial organization to continue to market and sell DSUVIA in the United States. In geographies where AcelRx decides not to commercialize products by itself, the Company may seek to out-license commercialization rights. The Company currently intends to commercialize and promote DSUVIA/DZUVEO outside the United States with one or more strategic partners, although it has not yet entered into any such arrangement. The timing of the resubmission of the Zalviso new drug application, or NDA, is in part dependent upon the finalization of the FDA’s new opioid approval guidelines and process. AcelRx intends to seek regulatory approval for Zalviso in the United States and, if successful, potentially promote Zalviso either by itself or with strategic partners. Zalviso is approved in Europe and will be commercialized by Grünenthal GmbH, or Grünenthal, through May 2021 (see Termination of Grünenthal Amended Agreements below).

The Company has incurred recurring operating losses and negative cash flows from operating activities since inception. Although Zalviso was approved for sale in Europe on September 18, 2015, the Company sold the majority of the royalty rights and certain commercial sales milestones it is entitled to receive under the Amended License Agreement (defined below) with Grünenthal to PDL BioPharma, Inc., or PDL, in a transaction referred to as the Royalty Monetization. In consideration of the termination of the Amended License Agreement, under the Royalty Monetization, the Company must use commercially reasonable efforts to negotiate a replacement license agreement with a third party. The Company expects to continue to incur operating losses and negative cash flows until such time as DSUVIA has gained market acceptance and generated significant revenues.

DSUVIA/DZUVEO

DSUVIA, known as DZUVEO in Europe, approved by the FDA in November 2018 and granted marketing approval by the EC in June 2018, is indicated for use in adults in a certified medically supervised healthcare setting, such as hospitals, surgical centers, and emergency departments, for the management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. DSUVIA was designed to provide rapid analgesia via a non-invasive route and to eliminate dosing errors associated with IV administration. DSUVIA is a single-strength solid dosage form administered sublingually via a single-dose applicator, or SDA, by healthcare professionals. Sufentanil is an opioid analgesic currently marketed for intravenous, or IV, and epidural anesthesia and analgesia. The sufentanil pharmacokinetic profile when delivered sublingually avoids the high peak plasma levels and short duration of action observed with IV administration.

DSUVIA was approved with a Risk Evaluation and Mitigation Strategy, or REMS, which restricts distribution to certified medically supervised healthcare settings in order to prevent respiratory depression resulting from accidental exposure. DSUVIA is only distributed to facilities certified in the DSUVIA REMS program following attestation by an authorized representative to comply with appropriate dispensing and use restrictions of DSUVIA. To become certified, a healthcare setting is required to train their healthcare professionals on the proper use of DSUVIA and have the ability to manage respiratory depression. DSUVIA is not available in retail pharmacies or for outpatient use. As part of the REMS program, the Company monitors distribution and audits wholesalers’ data, evaluates proper usage within the healthcare settings and monitors for any diversion and abuse. AcelRx will de-certify healthcare settings that are non-compliant with the REMS program.

Promotion Agreement

On March 15, 2020, the Company entered into the Agreement and Plan of Merger (as amended on May 27, 2020 and May 29, 2020, the Merger Agreement) and a Co-Promotion Agreement, or the Co-Promotion Agreement, with Tetraphase Pharmaceuticals, Inc., or Tetraphase, to co-promote DSUVIA and Tetraphases’s XERAVA™ (eravacycline). On June 4, 2020, Tetraphase terminated the Merger Agreement pursuant to its terms and paid AcelRx a termination fee . Net of the termination fee, the Company incurred charges of approximately $1.1 million in connection with the Merger Agreement. On July 28, 2020, Tetraphase was acquired by La Jolla Pharmaceutical Company, or La Jolla. On October 1, 2020, the Company entered into a Promotion Agreement, or the Promotion Agreement, with La Jolla and Tetraphase, effective as of September 30, 2020, pursuant to which the Company, La Jolla and Tetraphase restructured their co-promotion arrangement, with La Jolla agreeing to detail and promote DSUVIA and AcelRx and Tetraphase agreeing to terminate the Co-Promotion Agreement between them.

Under the terms of this agreement, La Jolla is responsible for maintaining compliance under the agreed marketing and promotion plan and achieving a minimum number of sales calls per calendar quarter. The Company will not detail and promote XERAVA™ (eravacycline) under this agreement.

The Promotion Agreement has a two-year term. The Company may terminate the agreement upon 30 days’ notice. After one year, La Jolla may terminate the agreement upon 30 days’ notice and may do so earlier in the event the Company undergoes a change of control and change in management. The Company pay La Jolla a revenue share on net sales of DSUVIA in the sales territories covered by the Promotion Agreement, other than sales to certain excluded accounts. These sales territories do not overlap with the territories covered by the Company’s sales force. If La Jolla fails to meet its detailing requirements in a given calendar quarter, it will pay the Company a royalty on net sales of XERAVA in the United States during such quarter.

There were no material revenues or expenses related to the Promotion Agreement in the year ended December 31, 2020.

Distribution Agreement

On July 17, 2020, the Company entered into a distribution agreement, or the Distribution Agreement, with Zimmer Biomet Dental, or ZB Dental, pursuant to which ZB Dental obtained the exclusive right to promote, market, sell, and arrange to distribute DSUVIA in the United States to clinicians, dentists, surgeons and other licensed health care practitioners that perform dental (including specialty dental), oral-maxillofacial, cranio-maxillofacial or oral surgery procedures, or Professionals, and their respective institutions and facilities that are permitted to use DSUVIA.

ZB Dental’s distribution rights are non-exclusive for crossover ambulatory surgery centers and certain government customers, and do not extend to ambulatory care centers outside the class of trade or into hospitals. ZB Dental will conduct any distribution activities in a manner consistent with DSUVIA’s FDA-approved indication and REMS program, and within the parameters established in the Distribution Agreement. ZB Dental has the right to sublicense its distribution rights to its qualified marketing partners but may not otherwise sublicense its distribution rights to any third party without our prior written consent.

There were no material revenues or expenses related to the Distribution Agreement in the year ended December 31, 2020.

Zalviso

Zalviso delivers 15 mcg sufentanil sublingually through a non-invasive delivery route via a pre-programmed, patient-controlled analgesia, or PCA, system. Zalviso is approved in Europe and is in late-stage development in the United States. The Company had initially submitted to the FDA an NDA seeking approval for Zalviso in September 2013 but received a complete response letter, or CRL, on July 25, 2014. Subsequently, the FDA requested an additional clinical study, IAP312, designed to evaluate the effectiveness of changes made to the functionality and usability of the Zalviso device and to take into account comments from the FDA on the study protocol. In the IAP312 study, for which top-line results were announced in August 2017, Zalviso met safety, satisfaction and device usability expectations. These results will supplement the three Phase 3 trials already completed in the Zalviso NDA resubmission.

Termination of Grünenthal Amended Agreements

On December 16, 2013, AcelRx and Grünenthal entered into a Collaboration and License Agreement, or the License Agreement, which was amended effective July 17, 2015 and September 20, 2016, or the Amended License Agreement, which granted Grünenthal rights to commercialize the Zalviso PCA system, or the Product, in the 28 European Union, or EU, member states, at the time of the agreement, plus Switzerland, Liechtenstein, Iceland, Norway and Australia (collectively, the Territory) for human use in pain treatment within, or dispensed by, hospitals, hospices, nursing homes and other medically supervised settings, (collectively, the Field). In September 2015, the EC granted marketing approval for the marketing authorization application, or MAA, previously submitted to the EMA, for Zalviso for the management of acute moderate-to-severe post-operative pain in adult patients. On December 16, 2013, AcelRx and Grünenthal, entered into a Manufacture and Supply Agreement, or the MSA, and together with the License Agreement, the Agreements. Under the MSA, the Company exclusively manufactured and supplied the Product to Grünenthal for the Field in the Territory. On July 22, 2015, the Company and Grünenthal amended the MSA, or the Amended MSA, effective as of July 17, 2015. The Amended MSA and the Amended License Agreement are referred to as the Grünenthal Agreements.

On May 18, 2020, the Company received a notice from Grünenthal that it had exercised its right to terminate the Grünenthal Agreements, effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory, a right it had under the Grünenthal Agreements. The rights to market and sell Zalviso in the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia, or the Territory, will revert back to the Company in May 2021.

Except as the context otherwise requires, when we refer to "we," "our," "us," the "Company" or "AcelRx" in this document, we mean AcelRx Pharmaceuticals, Inc., and its consolidated subsidiary. “DZUVEO” is a trademark, and “ACELRX”, “DSUVIA” and “Zalviso” are registered trademarks, all owned by AcelRx Pharmaceuticals, Inc. This report also contains trademarks and trade names that are the property of their respective owners.

Basis of Presentation

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and the accompanying notes. Actual results could differ from those estimates.

Reclassifications

Certain prior year amounts in the Consolidated Financial Statements have been reclassified to conform to the current year's presentation. In particular, the amounts reported in the Consolidated Balance Sheets as tax receivable and long-term tax receivable have been reclassified to prepaid expenses and other current assets, and other assets, respectively, at December 31, 2019. In addition, the amounts reported in the Consolidated Statements of Cash Flows as inventory impairment have been reclassified to other for the years ended December 31, 2019 and 2018, the amounts reported as tax receivable and other assets have been reclassified to prepaid expenses and other assets for the year ended December 31, 2019, and the amount reported as deferred rent has been reclassified to prepaid expenses and other assets for the year ended December 31, 2018.

Principles of Consolidation

The Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiary, ARPI LLC, which was formed in September 2015 for the sole purpose of facilitating the Royalty Monetization with PDL of the expected royalty stream and milestone payments due from the sales of Zalviso in the European Union by its commercial partner, Grünenthal, pursuant to the Amended License Agreement. All intercompany accounts and transactions have been eliminated in consolidation. Refer to Note 8 “Liability Related to Sale of Future Royalties” for additional information.

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying notes. Management evaluates its estimates on an ongoing basis including critical accounting policies. Estimates are based on historical experience and on various other market-specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.

Cash, Cash Equivalents and Short-Term Investments

The Company considers all highly liquid investments with an original maturity (at date of purchase) of three months or less to be cash equivalents. Cash and cash equivalents consist of cash on deposit with banks.

All marketable securities are classified as available-for-sale and consist of commercial paper, U.S. government sponsored enterprise debt securities and corporate debt securities. These securities are carried at estimated fair value, which is based on quoted market prices or observable market inputs of almost identical assets, with unrealized gains and losses included in accumulated other comprehensive income (loss). The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income or expense. The cost of securities sold is based on specific identification. The Company’s investments are subject to a periodic impairment review for other-than-temporary declines in fair value. The Company’s review includes the consideration of the cause of the impairment including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. When the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other-than-temporary, it reduces the carrying value of the security it holds and records a loss in the amount of such decline.

Fair Value of Financial Instruments

The Company measures and reports its cash equivalents, investments and financial liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows:

Level I—Unadjusted quoted prices in active markets for identical assets or liabilities;

Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities.

The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

Segment Information

The Company operates in a single segment, the development and commercialization of product candidates and products for the treatment of pain. The Company’s product sales revenue consists of sales of DSUVIA in the United States and Zalviso in Europe. The Company’s contract and collaboration revenue consists of non-cash royalty revenue, royalty revenue, and other revenue under the Grünenthal Agreements.

Concentration of Risk

The Company invests cash that is currently not being used for operational purposes in accordance with its investment policy in debt securities of U.S. government sponsored agencies, commercial paper and overnight deposits. The Company is exposed to credit risk in the event of default by the institutions holding the cash equivalents and available-for-sale securities to the extent recorded on the Consolidated Balance Sheets.

The Company relies on a single third-party supplier for the supply of sufentanil, the active pharmaceutical ingredient in DSUVIA and Zalviso, and various sole-source third-party contract manufacturer organizations to manufacture the DSUVIA SDA.

DSUVIA sales are concentrated with the DoD and in a limited number of wholesalers. Zalviso has been sold in Europe by Grünenthal, who terminated the Grünenthal Agreements, effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory. Revenue and accounts receivable have been concentrated with these customers.

Year Ended December 31,

Percent of Total Revenue

2020

2019

2018

Grünenthal
74.0 % 83.6 % 61.1 %

DoD
16.9 % 0 % 38.9 %

Wholesaler A
3.9 % 0 % 0 %

Wholesaler B
2.1 % 7.5 % 0 %

Wholesaler C
1.2 % 5.7 % 0 %

All others
1.9 % 3.2 % 0 %

Accounts Receivable, net

The need for a bad debt allowance is evaluated each reporting period based on the Company’s assessment of the credit worthiness of its customers or any other potential circumstances that could result in bad debt.

The Company has not experienced any losses with respect to the collection of its accounts receivable and believes that the entire accounts receivable balance as of December 31, 2020 is collectible.

As of December 31,

Percent of Accounts Receivable, Net

2020

2019

Customer A
79 % 0 %

Customer B
12 % 15 %

Customer C
6 % 5 %

Customer D
0 % 72 %

All Others
3 % 8 %

Inventories, net

Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method for all inventories. Inventory includes the cost of the active pharmaceutical ingredients, or API, raw materials and third-party contract manufacturing and packaging services. Indirect overhead costs associated with production and distribution are allocated to the appropriate cost pool and then absorbed into inventory based on the units produced or distributed, assuming normal capacity, in the applicable period. Indirect overhead costs in excess of normal capacity are recorded as period costs in the period incurred. DSUVIA was approved by the FDA in November 2018. Prior to FDA approval, all manufacturing costs for DSUVIA were expensed to research and development. Upon FDA approval, manufacturing costs for DSUVIA manufactured for commercial sale have been capitalized.

The Company's policy is to write down inventory that has become obsolete, inventory that has a cost basis in excess of its expected net realizable value and inventory in excess of expected requirements. The Company periodically evaluates the carrying value of inventory on hand for potential excess amount over demand using the same lower of cost or net realizable value approach as that used to value the inventory.

Property and Equipment, net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvements or the remaining lease term. Expenditures for repairs and maintenance, which do not extend the useful life of the property and equipment, are expensed as incurred. Upon retirement, the asset cost and related accumulated depreciation are relieved from the accompanying Consolidated Balance Sheets. Gains and losses associated with dispositions are reflected as a component of interest income and other income, net in the accompanying Consolidated Statements of Comprehensive Loss.

Impairment of Long-Lived Assets

The Company periodically assesses the impairment of long-lived assets and, if indicators of asset impairment exist, the Company assesses the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through an analysis of the undiscounted future expected operating cash flows. If impairment is indicated, the Company records the amount of such impairment for the excess of the carrying value of the asset over its estimated fair value. For example, if the Company is not successful in its commercialization of DSUVIA, and if approved, Zalviso, purchased equipment and manufacturing-related facility improvements the Company has made at its contract manufacturers could become impaired. The Company may determine that it is no longer probable that the Company will realize the future economic benefit associated with the costs of these assets through future manufacturing activities, and if so, the Company would record an impairment charge associated with these assets.

Contingent put option

The contingent put option associated with the Company’s Loan Agreement with Oxford is recorded as a liability. Changes in the fair value of the contingent put option are recognized as interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. For further discussion, see Note 6 “Long-Term Debt”.

Leases

In February 2016, the FASB issued Accounting Standards Update, or ASU, No. 2016-02, Leases (Topic 842), to enhance the transparency and comparability of financial reporting related to leasing arrangements. The Company adopted the standard effective January 1, 2019.

At the inception of an arrangement, the Company determines whether the arrangement is, or contains, a lease based on the unique facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received.

Lease expense is recognized over the expected term on a straight-line basis. Operating leases are recognized on the Consolidated Balance Sheet as operating lease right-of-use assets, operating lease liabilities current and operating lease liabilities non-current. As a result, the Company no longer recognizes deferred rent on the Consolidated Balance Sheet.

Revenue from Contracts with Customers

The Company follows the provisions of Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers. This guidance provides a unified model to determine how revenue is recognized. The Company recognizes revenue upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. The Company sells its products primarily through wholesale distributors.

In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation.

Product sales revenue

The Company sells its product primarily through distributors. Revenues from product sales are recognized when distributors obtain control of the Company’s product, which occurs at a point in time, upon delivery to such distributors. These distributors subsequently resell the product to certified medically supervised healthcare settings. In addition to distribution agreements with these customers, the Company enters into arrangements with group purchasing organizations, or GPOs, and other certified medically supervised healthcare settings that provide for privately negotiated discounts with respect to the purchase of its products. For revenue recognition under bill-and-hold arrangements, wherein the customer agrees to buy product from the Company but requests delivery at a later date, the Company deems that control passes to the customer when the product is ready for delivery. The Company recognizes revenue under these types of arrangements when a signed agreement is in place, the transaction is billable, the customer has significant risk and rewards for the product and the ability to direct the asset, the product has been set aside specifically for the customer, and the product cannot be redirected to another customer. Revenue from product sales is recorded at the transaction price, net of estimates for variable consideration consisting of chargebacks, government rebates, returns, distribution fees, GPO fees and product returns. Variable consideration is recorded at the time product sales are recognized resulting in a reduction in product revenue. The amount of variable consideration that is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Variable consideration is estimated using the most-likely amount method, which is the single-most likely outcome under a contract and is typically at the stated contractual rate. Where appropriate, these estimates take into consideration a range of possible outcomes that are probability-weighted in accordance with the expected value method under ASC Topic 606 for relevant factors. These factors include current contractual and statutory requirements, specific known market events and trends, industry data, and/or forecasted customer buying and payment patterns. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results vary materially from the Company’s estimates, the Company will adjust these estimates, which will affect revenue from product sales and earnings in the period such estimates are adjusted. These estimates include:

Chargebacks – The Company’s customers subsequently resell its product to qualified healthcare providers. In addition to distribution agreements with customers, the Company enters into arrangements with qualified healthcare providers that provide for chargebacks and discounts with respect to the purchase of our product. Chargebacks represent the estimated obligations resulting from contractual commitments to sell product to qualified healthcare providers at prices lower than the list prices charged to customers who directly purchase the product from the Company. Customers charge the Company for the difference between what they pay for the product and the ultimate selling price to the qualified healthcare providers. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. Chargeback amounts are determined at the time of resale to the qualified healthcare providers by customers, and the Company issues credits for such amounts generally within a few weeks of the customer's notification to the Company of the resale. Reserves for chargebacks consists of credits that the Company expects to issue for units that remain in the distribution channel inventories at each reporting period end that the Company expects will be sold to the qualified healthcare providers, and chargebacks for units that the Company’s customers have sold to the qualified healthcare providers, but for which credits have not been issued.

Government Rebates – The Company is subject to discount obligations under state Medicaid programs. The Company estimates its Medicaid rebates, and reserves are recorded in the same period the related product revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability that is included in accrued liabilities on the Consolidated Balance Sheet.

Returns – The Company allows its distributors to return product for credit 6 months prior to, and up to 12 months after, the product expiration date. As such, there may be a significant period of time between the time the product is shipped and the time the credit is issued on returned product.

Distribution Fees - Distribution fees include fees paid to certain customers for sales order management, data and distribution services. Distribution fees are recorded as a reduction of revenue in the period the related product revenue is recognized.

GPO Fees – The Company pays administrative fees to GPOs for services and access to data. These fees are based on contracted terms and are paid after the quarter in which the product was purchased by the GPOs’ members.

Trade Discounts and Allowances - The Company provides its customers with discounts which include early payment incentives that are explicitly stated in its contracts and are recorded as a reduction of revenue in the period the related product revenue is recognized.

The Company believes its estimated allowances for chargebacks, government rebates and product returns require a high degree of judgment and are subject to change based on its limited experience and certain quantitative and qualitative factors. The Company believes its estimated allowances for distribution fees, GPO fees and trade discounts and allowances do not require a high degree of judgment because the amounts are settled within a relatively short period of time. The Company will continue to assess its estimates of variable consideration as it accumulates additional historical data and will adjust these estimates accordingly. Changes in product revenue allowance estimates could materially affect the Company’s results of operations and financial position.

Contract and other collaboration revenue

The Company generates revenue from collaboration agreements. These agreements typically include payments for upfront signing or license fees, cost reimbursements for development and manufacturing services, milestone payments, product sales, and royalties on licensee’s future product sales. Product sales related revenue under these collaboration agreements is classified as product sales revenue, while other revenue generated from collaboration agreements is classified as contract and other collaboration revenue.

The Company entered into award contracts with U.S. Department of Defense, or the DoD, to support the development of DSUVIA. These contracts provided for the reimbursement of qualified expenses for research and development activities. Revenue under these arrangements was recognized when the related qualified research expenses were incurred. The Company was entitled to reimbursement of overhead costs associated with the study costs under the DoD arrangements. The Company estimated this overhead rate by utilizing forecasted expenditures. Final reimbursable overhead expenses were dependent on direct labor and direct reimbursable expenses throughout the life of each contract, which increased or decreased based on actual expenses incurred.

Performance Obligations

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in ASC Topic 606. The Company’s performance obligations include delivering product to its distributors, commercialization license rights, development services, services associated with the regulatory approval process, joint steering committee services, demonstration devices, manufacturing services, material rights for discounts on manufacturing services, and product supply.

The Company has optional additional items in contracts, which are considered marketing offers and are accounted for as separate contracts when the customer elects such options. Arrangements that include a promise for future commercial product supply and optional research and development services at the customer’s or the Company’s discretion are generally considered as options. The Company assesses if these options provide a material right to the licensee and if so, such material rights are accounted for as separate performance obligations. If the Company is entitled to additional payments when the customer exercises these options, any additional payments are recorded in revenue when the customer obtains control of the goods or services.

Transaction Price

The Company has both fixed and variable consideration. Variable consideration for product revenue is described as Net product sales in the Consolidated Statements of Comprehensive Loss. For collaboration agreements, non-refundable upfront fees and product supply selling prices are considered fixed, while milestone payments are identified as variable consideration when determining the transaction price. Funding of research and development activities is considered variable until such costs are reimbursed at which point, they are considered fixed. The Company allocates the total transaction price to each performance obligation based on the relative estimated standalone selling prices of the promised goods or services for each performance obligation.

At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone (such as a regulatory submission by the Company) is included in the transaction price. Milestone payments that are not within the control of the Company, such as approvals from regulators, are not considered probable of being achieved until those approvals are received.

For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (a) when the related sales occur, or (b) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Allocation of Consideration

As part of the accounting for collaboration arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. Estimated selling prices for license rights and material rights for discounts on manufacturing services are calculated using an income approach model and can include the following key assumptions: the development timeline, sales forecasts, costs of product sales, commercialization expenses, discount rate, the time which the manufacturing services are expected to be performed, and probabilities of technical and regulatory success. For all other performance obligations, the Company uses a cost- plus margin approach.

Timing of Recognition

Significant management judgment is required to determine the level of effort required under collaboration arrangements and the period over which the Company expects to complete its performance obligations under the arrangement. The Company estimates the performance period or measure of progress at the inception of the arrangement and re-evaluates it each reporting period. This re-evaluation may shorten or lengthen the period over which revenue is recognized. Changes to these estimates are recorded on a cumulative catch up basis. If the Company cannot reasonably estimate when its performance obligations either are completed or become inconsequential, then revenue recognition is deferred until the Company can reasonably make such estimates. Revenue is then recognized over the remaining estimated period of performance using the cumulative catch-up method. Revenue is recognized for products at a point in time when control of the product is transferred to the customer in an amount that reflects the consideration the Company expects to be entitled to in exchange for those product sales, which is typically once the product physically arrives at the customer, and for licenses of functional intellectual property at the point in time the customer can use and benefit from the license. For performance obligations that are services, revenue is recognized over time proportionate to the costs that the Company has incurred to perform the services using the cost-to-cost input method.

Cost of Goods Sold

Cost of goods sold for product revenue includes third party manufacturing costs, shipping and handling costs, and indirect overhead costs associated with production and distribution which are allocated to the appropriate cost pool and recognized when revenue is recognized. Indirect overhead costs in excess of normal capacity are recorded as period costs in the period incurred.

Under the Grünenthal Agreements, the Company sold Zalviso to Grünenthal at predetermined, contractual transfer prices that were less than the direct costs of manufacturing and recognized indirect costs as period costs where they were in excess of normal capacity and not recoverable on a lower of cost or net realizable value basis. Cost of goods sold for Zalviso shipped to Grünenthal includes the inventory costs of API, third-party contract manufacturing costs, packaging and distribution costs, shipping, handling and storage costs, depreciation and costs of the employees involved with production.

Research and Development Expenses

Research and development costs are charged to expense when incurred. Research and development expenses include salaries, employee benefits, including stock-based compensation, consultant fees, laboratory supplies, costs associated with clinical trials and manufacturing, including contract research organization fees, other professional services and allocations of corporate costs. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events.

Advertising Expenses

Advertising costs are expensed as incurred. Advertising expenses were $0.5 million, $1.1 million and $0.5 million for the years ended December 31, 2020, 2019 and 2018, respectively, and are included in selling, general and administrative expenses in the Consolidated Statements of Comprehensive Loss.

Stock-Based Compensation

Compensation expense for all stock-based payment awards made to employees and directors, including employee stock options and restricted stock units related to the 2011 Equity Incentive Plan, or 2011 EIP, and employee share purchases related to the 2011 Employee Stock Purchase Plan, or ESPP, is based on estimated fair values at grant date. The Company determines the grant date fair value of the awards using the Black-Scholes option-pricing model and generally recognizes the fair value as stock-based compensation expense on a straight-line basis over the vesting period of the respective awards.

The Black-Scholes option pricing model requires inputs such as expected term, expected volatility and risk-free interest rate. These inputs are subjective and generally require significant analysis and judgment to develop. The expected term, which represents the period of time that options granted are expected to be outstanding, is derived by analyzing the historical experience of similar awards, giving consideration to the contractual terms of the stock‑based awards, vesting schedules and expectations of future employee behavior. Expected volatilities are estimated using the historical stock price performance over the expected term of the option, which are adjusted as necessary for any other factors which may reasonably affect the volatility of AcelRx’s stock in the future. The risk‑free interest rate is based on the U.S. Treasury yield in effect at the time of the grant for the expected term of the award. The Company recognizes forfeitures when they occur and does not anticipate paying dividends in the near future.

Restructuring Costs

The Company's restructuring costs consist of employee termination benefit costs. Liabilities for costs associated with the cost reduction plan are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the Company notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the future service period.

On March 16, 2020, in connection with entering into the Co-Promotion Agreement, the Company initiated a reduction in headcount, designed to eliminate the overlap with the Tetraphase commercial team in order to more efficiently commercialize DSUVIA alongside the Tetraphase commercial team and reduce operating expenses. The Company eliminated 30 positions, primarily within the commercial organization. For the year ended December 31, 2020, the Company incurred and paid $0.5 million in employee termination benefits related to this restructuring.

The headcount reduction was completed in the first quarter of 2020. No additional expenses are anticipated in connection with this cost reduction plan.

Non-Cash Interest Income (Expense) on Liability Related to Sale of Future Royalties

In September 2015, the Company sold certain royalty and milestone payment rights from the sales of Zalviso in the European Union by Grünenthal, pursuant to the Grünenthal Agreements, to PDL for gross proceeds of $65.0 million. Grünenthal terminated the Grünenthal Agreements effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory. The rights to market and sell Zalviso in the Territory, will revert back to the Company in May 2021.

Under the Royalty Monetization, the Company has a continuing obligation to use commercially reasonable efforts to negotiate a replacement license agreement, or New Arrangement. Under the relevant accounting guidance, because of the Company’s significant continuing involvement, the Royalty Monetization is accounted for as a liability that is being amortized using the effective interest method over the life of the arrangement. In order to determine the amortization of the liability, the Company is required to estimate the total amount of future royalty and milestone payments to be received by ARPI LLC and payments made to PDL, up to a capped amount of $195.0 million, over the life of the arrangement. The aggregate future estimated royalty and milestone payments (subject to the capped amount), less the $61.2 million of net proceeds the Company received, are amortized as interest expense over the life of the liability. Consequently, the Company imputes interest on the unamortized portion of the liability and records interest expense, or interest income, as these estimates are updated.

There are a number of factors that could materially affect the amount and timing of royalty and milestone payments from Zalviso in Europe, most of which are not within the Company’s control. Such factors include, but are not limited to, the success of any future sales and promotion of Zalviso under any New Arrangement, if achieved; changing standards of care; the introduction of competing products; manufacturing or other delays; intellectual property matters; adverse events that result in governmental health authority imposed restrictions on the use of Zalviso; significant changes in foreign exchange rates as the royalties remitted to ARPI LLC are made in U.S. dollars; and other events or circumstances that could result in reduced royalty payments from European sales of Zalviso, all of which may result in a reduction of non-cash royalty revenues and the non-cash interest expense over the life of the Royalty Monetization. Conversely, if sales of Zalviso in Europe are greater than expected, the non-cash royalty revenues and the non-cash interest expense recorded by the Company would be greater over the term of the Royalty Monetization. The Company periodically assesses the expected royalty and milestone payments using a combination of historical results, internal projections and forecasts from external sources. To the extent such payments are greater or less than the Company’s initial estimates or the timing of such payments is materially different than its original estimates, the Company will prospectively adjust the amortization of the liability and the effective interest rate. Because estimated sales forecasts and payments may vary over the life of the Royalty Monetization, the Company may be required to recognize interest income as the imputed interest rate is adjusted prospectively to reflect the revised effective interest rate over the term of the Royalty Monetization.

The Company records non-cash royalty revenues and non-cash interest income (expense), net, within its Consolidated Statements of Comprehensive Loss over the term of the Royalty Monetization.

When the expected payments under the Royalty Monetization are lower than the gross proceeds of $65.0 million received, the Company defers recognition of any probable contingent gain until the Royalty Monetization liability expires.

Comprehensive Loss

Comprehensive loss is comprised of net loss and other comprehensive income (loss) and is disclosed in the Consolidated Statements of Comprehensive Loss. For the Company, other comprehensive income (loss) consists of changes in unrealized gains and losses on the Company’s investments.

Income Taxes

Deferred tax assets and liabilities are measured based on differences between the financial reporting and tax basis of assets and liabilities using enacted rates and laws that are expected to be in effect when the differences are expected to reverse. The Company records a valuation allowance for the full amount of deferred assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.

Net Loss per Share of Common Stock

The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, convertible preferred stock, options to purchase common stock, restricted stock subject to repurchase, restricted stock units, warrants to purchase convertible preferred stock and warrants to purchase common stock were considered to be common stock equivalents. In periods with a reported net loss, such common stock equivalents are excluded from the calculation of diluted net loss per share of common stock if their effect is antidilutive. For additional information regarding the net loss per share, see Note 13 “Net Loss per Share of Common Stock”.

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, “Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments,” or ASU 2016-13. ASU 2016-13 replaces the incurred loss impairment model in current GAAP with a model that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. ASU 2016-13 is effective for the Company beginning January 1, 2023, with early adoption allowed beginning January 1, 2020. In May 2019, the FASB issued ASU 2019-05, “Financial Instruments – Credit Losses,” or ASU 2019-05, to allow entities to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost upon adoption of the new credit losses standard. The new effective dates and transition align with those of ASU 2016-13. Management is currently assessing the date of adoption and the impact ASU 2016-13 and ASU 2019-05 will have on the Company, but it does not anticipate adoption of these new standards to have a material impact on the Company’s financial position, results of operations or cash flows.

In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The amendments provide optional guidance for a limited time to ease the potential burden in accounting for reference rate reform. The new guidance provides optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The amendments apply only to contracts and hedging relationships that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform. These amendments are effective immediately and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2022. The FASB also issued ASU No. 2021-01, “Reference Rate Reform (Topic 848): Scope” in January 2021. It clarifies that certain optional expedients and exceptions in Topic 848 apply to derivatives that are affected by the discounting transition. The amendments in this ASU affect the guidance in ASU 2020-04 and are effective in the same timeframe as ASU 2020-04. The Company is currently evaluating its contracts and the optional expedients and exceptions provided by the new standard, but it does not anticipate its adoption to have a material impact on the Company’s financial position, results of operations or cash flows.

Note 2 - Investments and Fair Value Measurement

12 Months Ended

Dec. 31, 2020

Investments and Fair Value Measurement Disclosure [Text Block]

2. Investments and Fair Value Measurement

Investments

The Company classifies its marketable securities as available-for-sale and records its investments at fair value. Available-for-sale securities are carried at estimated fair value based on quoted market prices or observable market inputs of almost identical assets, with the unrealized holding gains and losses included in accumulated other comprehensive income. Marketable securities which have maturities beyond one year as of the end of the reporting period are classified as non-current.

The table below summarizes the Company’s cash, cash equivalents and investments (in thousands):

	As of December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	5,181	$	—	$	—	$	5,181
Money market funds		3,996		—		—		3,996
Commercial paper		18,097		—		—		18,097
Total cash and cash equivalents		27,274		—		—		27,274

Short-term investments:
U.S. government agency securities		5,818		—		—		5,818
Commercial paper		9,794		—		—		9,794
Total short-term investments		15,612		—		—		15,612
Total cash, cash equivalents and short-term investments	$	42,886	$	—	$	—	$	42,886

	As of December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	1,957	$	—	$	—	$	1,957
Money market funds		598		—		—		598
Commercial paper		12,129		—		—		12,129
Total cash and cash equivalents		14,684		—		—		14,684

Short-term investments:
U.S. government agency securities		14,268		—		—		14,268
Commercial paper		27,131		—		—		27,131
Corporate debt securities		10,054		—		—		10,054
Total short-term investments		51,453		—		—		51,453
Total cash, cash equivalents and short-term investments	$	66,137	$	—	$	—	$	66,137

None of the available-for-sale securities held by the Company had material unrealized losses and there were no realized losses for the years ended December 31, 2020 and 2019. There were no other-than-temporary impairments for these securities as of December 31, 2020 or 2019. No gross realized gains or losses were recognized on the available-for-sale securities and, accordingly, there were no amounts reclassified out of accumulated other comprehensive income to earnings during the years ended December 31, 2020 and 2019.

As of December 31, 2020 and 2019, the contractual maturity of all investments held was less than one year.

Fair Value Measurement

The Company’s financial instruments consist of Level I and II assets and Level III liabilities. Money market funds are highly liquid investments and are actively traded. The pricing information on these investment instruments are readily available and can be independently validated as of the measurement date. This approach results in the classification of these securities as Level 1 of the fair value hierarchy. For Level II instruments, the Company estimates fair value by utilizing third party pricing services in developing fair value measurements where fair value is based on valuation methodologies such as models using observable market inputs, including benchmark yields, reported trades, broker/dealer quotes, bids, offers and other reference data. Such Level II instruments typically include U.S. treasury, U.S. government agency securities and commercial paper. As of December 31, 2020, and December 31, 2019, the Company held, in addition to Level II assets, a contingent put option liability associated with the Loan Agreement with Oxford. See Note 6 “Long-Term Debt” for further description. The Company’s estimate of fair value of the contingent put option liability was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated both with and without the presence of the default provisions, holding all other assumptions constant. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option, which is included under other long-term liabilities on the Consolidated Balance Sheets. Changes to the estimated fair value of this liability is recorded in interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. The fair value of the underlying debt facility is estimated by calculating the expected cash flows in consideration of an estimated probability of default and expected recovery rate in default and discounting such cash flows back to the reporting date using a risk-free rate.

The following table sets forth the fair value of the Company’s financial assets and liabilities by level within the fair value hierarchy (in thousands):

	As of December 31, 2020
	Fair Value		Level I		Level II		Level III
Assets
Money market funds	$	3,996	$	3,996	$	—	$	—
U.S. government agency securities		5,818		—		5,818		—
Commercial paper		27,891		—		27,891		—
Total assets measured at fair value	$	37,705	$	3,996	$	33,709	$	—

Liabilities
Contingent put option liability	$	246	$	—	$	—	$	246
Total liabilities measured at fair value	$	246	$	—	$	—	$	246

	As of December 31, 2019
	Fair Value		Level I		Level II		Level III
Assets
Money market funds	$	598	$	598	$	—	$	—
U.S. government agency securities		14,268		—		14,268		—
Commercial paper		39,260		—		39,260		—
Corporate debt securities		10,054		—		10,054		—
Total assets measured at fair value	$	64,180	$	598	$	63,582	$	—

Liabilities
Contingent put option liability	$	437	$	—	$	—	$	437
Total liabilities measured at fair value	$	437	$	—	$	—	$	437

The following table sets forth a summary of the changes in the fair value of the Company’s Level III financial liabilities for the years ended December 31, 2020 and 2019 (in thousands):

	Year Ended December 31, 2020
Fair value—beginning of period	$	437
Change in fair value of contingent put option associated with the Loan Agreement		(191	)
Fair value—end of period	$	246

	Year Ended December 31, 2019
Fair value—beginning of period	$	121
Change in fair value of contingent put option associated with the Loan Agreement		437
Change in fair value of contingent put option associated with the Prior Agreement		(121	)
Fair value—end of period	$	437

Note 3 - Inventories, Net

12 Months Ended

Dec. 31, 2020

Inventory Disclosure [Text Block]

3. Inventories, net

Inventories consist of finished goods, raw materials and work in process and are stated at the lower of cost or net realizable value and consist of the following (in thousands):

	As of December 31,
	2020		2019
Raw materials	$	257	$	1,153
Work-in-process		30		593
Finished goods		1,339		1,549
Inventories	$	1,626	$	3,295

During the year ended December 31, 2020, the Company recorded inventory impairment charges of approximately $0.7 million, of which $0.3 million related to the termination of the Amended Agreements, while $0.4 million related to DSUVIA inventory, primarily inventory that may expire before being sold. During the year ended December 31, 2019, the Company recorded a write-down of inventory of approximately $1.0 million, which represented initial DSUVIA batches produced for development and therefore represented shorter dated product than batches manufactured for commercial sale. Inventory that has been impaired is recorded in cost of goods sold in the accompanying Consolidated Statements of Comprehensive Loss.

Note 4 - Property and Equipment, Net

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment Disclosure [Text Block]

4. Property and Equipment, net

Property and equipment, net consist of the following (in thousands):

	As of December 31,
	2020			2019
Laboratory equipment	$	4,406		$	4,389
Leasehold improvements		4,616			4,616
Computer equipment and software		1,724			1,749
Construction in process		14,101			11,949
Tooling		1,109			1,109
Furniture and fixtures		292			292

		26,248			24,104
Less accumulated depreciation and amortization		(10,589	)		(9,552	)
Property and equipment, net	$	15,659		$	14,552

Depreciation and amortization expense was $1.1 million, $0.9 million and $0.5 million during the years ended December 31, 2020, 2019 and 2018, respectively.

Note 5 - Revenue From Contracts With Customers

12 Months Ended

Dec. 31, 2020

Revenue from Contract with Customer [Text Block]

5. Revenue from Contracts with Customers

The following table summarizes revenue from contracts with customers for the years ended December 31, 2020, 2019 and 2018 into categories that depict how the nature, amount, timing and uncertainty of revenue and cash flows are affected by economic factors (in thousands):

	December 31,
	2020		2019		2018
Product sales:
DSUVIA	$	1,409	$	377	$	—
Zalviso		1,112		1,453		825
Total product sales		2,521		1,830		825
Contract and other collaboration:
DoD Contract revenue		—		—		838
Non-cash royalty revenue related to Royalty Monetization (See Note 8)		242		312		289
Royalty revenue		81		104		96
Other revenue		2,572		43		103
Total revenues from contract and other collaboration		2,895		459		1,326
Total revenue	$	5,416	$	2,289	$	2,151

For additional detail on the Company’s accounting policy regarding revenue recognition, refer to Note 1 “Organization and Summary of Significant Accounting Policies - Revenue from Contracts with Customers.”

Product Sales

The Company’s commercial launch of DSUVIA in the United States occurred in the first quarter of 2019. Zalviso has been sold in Europe by the Company’s collaboration partner, Grünenthal. Grünenthal has exercised its right to terminate the Amended Agreements, effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory.

Contract and Other Collaboration

Amended License Agreement

Under the Amended License Agreement with Grünenthal, the Company was eligible to receive approximately $194.5 million in additional milestone payments, based upon successful regulatory and product development efforts ($28.5 million) and net sales target achievements ($166.0 million). A portion of the tiered royalty payments earned were paid to PDL in connection with the Royalty Monetization. For additional information on the Royalty Monetization with PDL, see Note 8 “Liability Related to Sale of Future Royalties”. On August 31, 2020, PDL announced it sold its royalty interest for Zalviso to SWK Funding, LLC.

Amended MSA

Under the terms of the Amended MSA with Grünenthal, the Company manufactured and supplied the Product for use in the Field for the Territory exclusively for Grünenthal. The Product was supplied at prices approximating the Company’s manufacturing cost, subject to certain caps, as defined in the MSA Amendment.

The Grünenthal Agreements entitled the Company to receive additional payments upon the achievement of certain development milestones which related to post approval product enhancements, expanded market opportunities and manufacturing efficiencies for Zalviso and required future research, development and regulatory activities. These payments were excluded from the transaction price as they were considered payments for optional additional services elected by Grünenthal.

The Grünenthal Agreements also included milestone payments related to specified net sales targets, totaling $166.0 million. These payments were considered sales-based license royalties under ASC Topic 606 and would have been recognized apart from the other contract consideration when the related sales occurred. These net sales targets were not achieved prior to the termination of the Grünenthal Agreements.

In May 2020, upon notification of early termination by Grünenthal, the Company recognized approximately $2.6 million of deferred revenue under the Grünenthal Agreements.

DoD Contract

On May 11, 2015, the Company entered into an award contract (referred to as the DoD Contract) supported by the Clinical and Rehabilitative Medicine Research Program, or CRMRP, of the United States Army Medical Research and Materiel Command, or the USAMRMC, within the U.S. Department of Defense, or the DoD, in which the DoD agreed to provide up to $17.0 million to the Company in order to support the development of DSUVIA. The DoD contract period of performance ended on February 28, 2019.

Contract Liability

At December 31, 2020, the Company’s deferred revenue balance related to the significant and incremental discount on Zalviso manufacturing services for Grünenthal. In May 2020, upon notification of early termination by Grünenthal, the Company recognized approximately $2.6 million of deferred revenue for this discount on Zalviso manufacturing services which were no longer a performance obligation. At December 31, 2019, approximately $3.1 million of deferred revenue, $0.3 million of which represented the current portion, was attributable to the significant and incremental discount on Zalviso manufacturing services for Grünenthal.

The following table presents changes in the Company’s contract liability for the year ended December 31, 2020:

	Balance at Beginning of the Period		Additions		Deductions			Balance at the end of the Period
	(in thousands)
Contract liability:
Deferred revenue – Amended Agreements	$	3,244	$	—	$	(3,195	)	$	49

For the years ended December 31, 2020 and 2019, the Company recognized the following revenue from performance obligations satisfied (in thousands):

	Year ended December 31, 2020		Year ended December 31, 2019
Amounts included in contract liabilities at the beginning of the period:
Performance obligations satisfied	$	623	$	315
Performance obligations eliminated upon termination		2,572		—
New activities in the period from performance obligations satisfied:
Performance obligations satisfied		488		1,181
Total revenue from performance obligations satisfied or eliminated	$	3,683	$	1,496

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

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Note 6 - Long-term Debt

12 Months Ended

Dec. 31, 2020

Long-term Debt [Text Block]

6. Long-Term Debt

Prior Agreement with Hercules

On March 2, 2017, the Company entered into an Amended and Restated Loan and Security Agreement with Hercules Capital Funding Trust 2014-1 and Hercules Technology II, L.P., or Hercules, or the Prior Agreement. On May 30, 2019, the Company used approximately $8.9 million of the proceeds from the Loan Agreement with Oxford (described below) to repay its outstanding obligations under the Prior Agreement, including the outstanding principal plus accrued interest of $7.4 million, and the End of Term Fee of $1.3 million. The Company accounted for the termination of the Prior Agreement as a debt extinguishment and, accordingly, incurred a loss of approximately $0.2 million associated with the unamortized End of Term Fee.

Interest expense related to the Prior Agreement was $0.0 million, $0.6 million and $2.2 million for the years ended December 31, 2020, 2019 and 2018, respectively.

Loan Agreement with Oxford

On May 30, 2019, the Company entered into the Loan Agreement with Oxford as the Lender. Under the Loan Agreement, the Lender made a term loan to the Company in an aggregate principal amount of $25.0 million, or the Loan, which was funded on May 30, 2019. The Company used approximately $8.9 million of the proceeds from the Loan to repay its outstanding obligations under the Prior Agreement, as described above. After deducting all loan initiation costs and outstanding interest on the Prior Agreement, the Company received $15.9 million in net proceeds.

The interest rate is calculated at a rate equal to the sum of (a) the greater of (i) the 30-day U.S. LIBOR rate reported in The Wall Street Journal on the last business day of the month that immediately precedes the month in which the interest will accrue and (ii) 2.50%, plus (b) 6.75%. On July 27, 2017, the Financial Conduct Authority, or FCA, in the U.K. announced that it would phase out LIBOR as a benchmark by the end of 2021. It is unclear whether new methods of calculating LIBOR will be established such that it continues to exist after 2021 or if LIBOR will be replaced with an alternative reference rate; however, the Company does not believe such changes would have a material adverse effect on its financing costs. Payments on the Loan are interest-only until July 1, 2020 followed by equal principal payments and monthly accrued interest payments through the scheduled maturity date of June 1, 2023. At the Company’s election, the interest-only period may be extended to July 1, 2021, if prior to June 30, 2020, the Company receives unrestricted net cash proceeds of at least $45.0 million from either (i) the issuance and sale of equity securities, or (ii) “up front” payments in connection with a joint venture, collaboration or other partnering transaction, both of which are on terms and conditions acceptable to the Lender. A final payment equal to 5% of the aggregate principal amount of the Loan, or EOT Fee, will be due at the earlier of the maturity date, acceleration of the Loan, or prepayment of the Loan. The Company’s obligations under the Loan Agreement are secured by a security interest in all the assets of the Company, other than the Company’s intellectual property which is subject to a negative pledge.

The Company may prepay the Loan at any time. If the Loan is paid prior to the maturity date, the Company will pay the Lender a prepayment charge, based on a percentage of the then outstanding principal balance, equal to 1.5% if the prepayment occurs after May 30, 2020, but on or before May 30, 2021, or 1% if the prepayment occurs after May 30, 2021. Upon voluntary or mandatory prepayment, in addition to the prepayment charge, the Company is required to pay the EOT Fee, Lender’s expenses and all outstanding principal and accrued interest through the prepayment date.

The Loan Agreement includes customary representations and covenants that, subject to exceptions, will restrict the Company’s ability to do the following things: declare dividends or redeem or repurchase equity interests; incur additional liens; make loans and investments; incur additional indebtedness; engage in mergers, acquisitions, and asset sales; transact with affiliates; undergo a change in control; add or change business locations; and engage in businesses that are not related to its existing business. The Loan Agreement requires that the Company always maintain unrestricted cash of not less than $5.0 million in accounts subject to control agreements in favor of Lender, tested monthly as of the last day of the month.

The Loan Agreement also includes standard events of default, including payment defaults, breaches of covenants following any applicable cure period, a material impairment in the perfection or priority of the Lender’s security interest or in the value of the collateral, a material adverse change in business, operations or the prospect of repayment, events relating to bankruptcy or insolvency. The Loan also contains a cross default provision, under which if a third party (under any agreement) has the right to accelerate indebtedness greater than $250,000, the Loan would also be considered in default. In addition, the Loan defines events which negatively impact government approvals, judgements in excess of $500,000 and the delisting of the Company’s shares of common stock on the Nasdaq Global Market, or Nasdaq, as events of default. Upon the occurrence of an event of default, a default interest rate of an additional 5% may be applied to the outstanding loan balances, and the Lender may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Loan Agreement. Acceleration would result in the payment of any applicable prepayment charges and application of the default interest rate to the outstanding balance until payment is made if full. The Company bifurcated a compound derivative liability related to a contingent interest feature and acceleration upon default provision (contingent put option) provided to the Lender. The bifurcated embedded derivative must be valued and separately accounted for in the Company’s consolidated financial statements. The contingent put option liability is classified as a component of other long-term liabilities. As of December 31, 2020, the estimated fair value of the contingent put option liability was $0.2 million which was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated, both with and without the presence of the default provisions, holding all other assumptions constant. See Note 2 “Investments and Fair Value Measurement” for further description.

The accrued balance due under the Loan Agreement was $21.0 million and $24.2 million at December 31, 2020 and 2019, respectively. Interest expense related to the Loan Agreement was $3.2 million, of which $0.9 million represented amortization of the debt discount, and $1.9 million, $0.6 million of which represented amortization of the debt discount, for the years ended December 31, 2020 and 2019, respectively.

Non-Interest Bearing Payments for the Construction of Leasehold Improvements

In August 2019, the Company entered into a Site Readiness Agreement, or SRA, with a potential Contract Manufacturing Organization, or CMO, in contemplation of entering into a commercial supply agreement for its product DSUVIA® at a future date. Under the SRA, the Company is building out a suite within the CMO’s production facility. If additional equipment and facility modifications are required to meet the Company’s product needs, the Company may be required to contribute to the cost of such additional equipment and facility modifications. The Company has determined that it is the owner of the leasehold improvements related to the build-out which will be paid for in four annual installments of $0.5 million through July 2022. As of December 31, 2020, the accrued balance under the SRA is $0.8 million, and $1.7 million of these leasehold improvements have been capitalized. The effective interest rate related to the payments at December 31, 2020 was 14.35%. The leasehold improvements are recorded as property and equipment, net, in the Consolidated Balance Sheets.

The following table summarizes the balance of the future payments at December 31, 2020 (in thousands):

	As of December 31, 2020
Present value of the face amount of $1.0 million	$	865
Less: current portion		402
Long-term debt, net of current portion	$	463

Future Payments on Long-Term Debt

The following table summarizes the outstanding future payments associated with the Company’s long-term debt as of December 31, 2020 (in thousands):

2021	$	10,429
2022		9,647
2023		5,530
Total payments		25,606
Less amount representing interest		(2,523	)
Notes payable, gross		23,083
Less: Unamortized portion of EOT Fee		(524	)
Less: Unamortized discount on notes payable		(684	)
Long-term debt		21,875
Less current portion		(8,735	)
Long-term debt, net of current portion	$	13,140

Note 7 - Leases

12 Months Ended

Dec. 31, 2020

Lessee, Operating Leases [Text Block]

7. Leases

Office Lease

The Company leases office and laboratory space for its corporate headquarters, located at 351 Galveston Drive, Redwood City, California. In June 2017, the Company renegotiated the Lease with its Landlord, or the New Lease. The New Lease is effective from February 1, 2018 through January 31, 2024 and contains a renewal option for a six-year extension after the current expiration date. The Company does not expect that the renewal option will be exercised and has therefore excluded the option from the calculation of the right of use asset and lease liability. The initial monthly rent is approximately $0.1 million with annual increases of 3% commencing on February 1^st. The lease includes non-lease components (i.e., property management costs) that are paid separately from rent based on actual costs incurred and therefore were not included in the right-of-use asset and liability but are reflected as an expense in the period incurred. In calculating the present value of the lease payments, the Company has elected to utilize its incremental borrowing rate based on the remaining lease term.

On January 2, 2019, the Company entered into an agreement to sublease approximately 47% of its office and laboratory space effective February 16, 2019 and expiring on January 31, 2024, or the Sublease. The initial monthly rent from the sublessee is approximately $48,000 per month with annual increases of 3% commencing on February 1, 2019. Under the Sublease agreement, the sublessee was granted early access to the facility on January 2, 2019, which is deemed the lease commencement date and rent was abated for 45 days until the effective date of the lease. The sublessee is obligated to pay its proportionate share of property management costs on a pass-through basis. The Company incurred a total of $0.4 million in initial direct costs in entering the sublease, of which approximately $0.2 million is related to the tenant improvement allowance transferred to the sublessee. Initial direct costs are being amortized over the term of the sublease.

The transfer of the tenant improvement allowance to the sublessee resulted in a change in cash flows for the New Lease and was accounted for as a modification with changes in lease term and consideration. As a result, the Company remeasured the lease liability with the revised lease payments and recognized approximately $24,000 as a decrease to the lease liability, with a corresponding adjustment to the right-of-use asset.

Contract Manufacturing Lease

On December 12, 2012, the Company entered into an agreement for commercial supply manufacturing services related to the Company’s Zalviso drug product with a contract manufacturing organization. The initial term of the agreement was through December 31, 2017, which term automatically renews in two-year increments unless earlier terminated by either party by giving eighteen months’ notice. Commencing in 2013, the Company is required to make overhead fee payments each year of $0.2 million, prorated based on aggregate revenues. The Company has determined that this fee is an in-substance fixed lease payment as it represents the minimum annual payment under the contract. The Company concluded that this agreement contains an embedded lease as the clean rooms have been built specifically for production of the Company’s product and their use is effectively controlled by the Company as it has priority over the space during the term of the agreement. The Company accounts for the agreement as an operating lease and has evaluated the non-cancelable term to be through the binding commitment date of June 30, 2022.

The components of lease expense are presented in the following table (in thousands):

	Year ended December 31, 2020			Year ended December 31, 2019
Operating lease costs	$	1,360		$	1,360
Sublease income		(598	)		(596	)
Net lease costs	$	762		$	764

Other information related to the operating leases is presented in the following table (in thousands):

	Year ended December 31, 2020		Year ended December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$	1,268	$	1,084
Supplemental non-cash disclosures of lease activities:
Transfer of tenant improvement allowance to sublease	$	—	$	242
Right-of-use assets obtained in exchange for new operating lease liabilities	$	—	$	4,730

The weighted average remaining lease term and discount rate related to the operating leases are presented in the following table:

	December 31,			December 31,
	2020			2019
Weighted-average remaining lease term – operating leases (years)	3.1			4.1
Weighted-average remaining discount rate – operating leases		11.7	%		11.7	%

Maturities of lease liabilities as of December 31, 2020 are presented in the following table (in thousands):

Year:
2021	$	1,504
2022		1,445
2023		1,386
2024		116
Total future minimum lease payments		4,451
Less imputed interest		(727	)
Total	$	3,724

Reported as:
Operating lease liabilities	$	1,118
Operating lease liabilities, net of current portion		2,606
Total lease liability	$	3,724

Future minimum sublease payments as of December 31, 2020 are presented in the following table (in thousands):

Year:
2021	$	610
2022		629
2023		648
2024		54
Total future minimum sublease payments	$	1,941

The rent receivable balance is reported in the Consolidated Balance Sheets as follows (in thousands):

Reported as:
Prepaid expenses and other current assets	$	96
Other assets		258
Total rent receivable	$	354

Note 8 - Liability Related to Sale of Future Royalties

12 Months Ended

Dec. 31, 2020

8. Liability Related to Sale of Future Royalties

On September 18, 2015, the Company consummated the Royalty Monetization, in which it sold certain royalty and milestone payment rights to its newly formed wholly owned subsidiary, ARPI LLC, pursuant to a Purchase and Sale Agreement, or PSA. Subsequently, ARPI LLC sold the royalty and milestone payment rights to PDL for an upfront cash purchase price of $65.0 million, subject to a capped amount of $195.0 million pursuant to the Subsequent Purchase and Sale Agreement, or SPSA. Under the SPSA, PDL was entitled to receive 75% of the European royalties under the Amended License Agreement as well as 80% of the first four commercial milestones, worth $35.6 million (or 80% of $44.5 million), subject to the capped amount. The Company was entitled to receive 25% of the royalties, 20% of the first four commercial milestones, 100% of the remaining commercial milestones and all remaining development milestones of $43.5 million, including the $15.0 million payment for the marketing approval by the EC of the MAA for Zalviso.

Under the relevant accounting guidance, because of the Company’s significant continuing involvement, the Royalty Monetization has been accounted for as a liability that will be amortized using the effective interest method over the life of the arrangement. In order to determine the amortization of the liability, the Company is required to estimate the total amount of future royalty and milestone payments to be received by ARPI LLC and paid to PDL, up to a capped amount of $195.0 million, over the life of the arrangement. The aggregate future estimated royalty and milestone payments (subject to the capped amount), less the $61.2 million of net proceeds the Company received will be recorded as interest expense over the life of the liability. Consequently, the Company imputes interest on the unamortized portion of the liability and records interest expense relating to the Royalty Monetization accordingly.

The Company periodically assesses the expected royalty and milestone payments using a combination of historical results, internal projections and forecasts from external sources. To the extent such payments are greater or less than the Company’s initial estimates or the timing of such payments is materially different than its original estimates, the Company will prospectively adjust the amortization of the liability and the effective interest rate. During the three months ended June 30, 2019, the Company made a material revision to its estimates which resulted in an interest income rate on the Royalty Monetization liability balance at a prospective average rate of approximately 4.2%, which will be applied over the remaining term of the agreement. The change in estimate of future payments to PDL was a result of lower projected European royalties and milestones from sales of Zalviso over the life of the liability. The change in estimate results in interest income being recognized prospectively, over the remaining term of the agreement, as the estimated expected payments are less than the $65.0 million in gross proceeds received. During the three months ended June 30, 2020, Grünenthal notified the Company that it was terminating the Amended License Agreement, effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory. The rights to market and sell Zalviso in the Territory, will revert back to the Company in May 2021. There is a continuing obligation on the Company’s part, through the term of the Royalty Monetization, to use commercially reasonable efforts to negotiate a replacement license agreement, or New Arrangement. However, without a New Arrangement to commercialize Zalviso in the Territory, the Company is currently unable to reliably estimate the future payments to PDL over the remaining life of the Royalty Monetization. If the Company is unable to find a New Arrangement, a contingent gain of up to approximately $65 million may be recognized when it is realized upon expiration of the liability at the end of the Royalty Monetization term. Due to the significant judgments and factors related to the estimates of future payments under the Royalty Monetization, there are significant uncertainties surrounding the amount and timing of future payments and the probability of realization of the estimated contingent gain.

The change in estimate reduced the effective interest rate over the life of the liability to 0% by recording interest income over the remaining term of the arrangement as an offset to the interest expense that was recognized in prior periods and resulted in a decrease of $8.1 million to the net loss, or $0.10 per share of common stock, basic and diluted, for the year ended December 31, 2019. The effective interest income rate for the years ended December 31, 2020 and 2019 was approximately 3.6% and 1.4%, respectively. During the three months ended December 31, 2018, the Company revised its estimates as a result of lower projected European royalties from sales of Zalviso over the life of the liability because the product launch was progressing more slowly than originally expected. The effective interest expense rate for the year ended December 31, 2018 was approximately 11.6%.

The following table shows the activity within the liability account during the year ended December 31, 2020 (in thousands):

	Year ended December 31, 2020			Period from inception to December 31, 2020
Liability related to sale of future royalties — beginning balance	$	92,035		$	—
Proceeds from sale of future royalties		—			61,184
Non-cash royalty revenue		(254	)		(938	)
Non-cash interest (income) expense recognized		(3,310	)		28,225
Liability related to sale of future royalties as of December 31, 2020		88,471			88,471
Less: current portion		(106	)		(106	)
Liability related to sale of future royalties — net of current portion	$	88,365		$	88,365

As royalties are remitted to PDL from ARPI LLC, as described in Note 1 “Organization and Summary of Significant Accounting Policies,” the balance of the liability will be effectively repaid over the life of the agreement. The Company will record non-cash royalty revenues and non-cash interest expense within its Consolidated Statements of Comprehensive Loss over the term of the Royalty Monetization. On August 31, 2020, PDL announced it sold its royalty interest for Zalviso to SWK Funding, LLC.

Note 9 - Warrants

12 Months Ended

Dec. 31, 2020

Warrants Disclosure [Text Block]

9. Warrants

Loan Agreement Warrants

In connection with the Loan Agreement, on May 30, 2019, the Company issued warrants to the Lender and its affiliates, which are exercisable for an aggregate of 176,679 shares of the Company’s common stock with a per share exercise price of $2.83, or the Warrants. The Warrants may be exercised on a cashless basis. The Warrants are exercisable for a term beginning on the date of issuance and ending on the earlier to occur of ten years from the date of issuance or the consummation of certain acquisitions of the Company as set forth in the Warrants. The number of shares for which the Warrants are exercisable and the associated exercise price are subject to certain proportional adjustments as set forth in the Warrants.

The Company estimated the fair value of these Warrants as of the issuance date to be $0.4 million, which was used in estimating the fair value of the debt instrument and was recorded as equity. The fair value of the Warrants was calculated using the Black-Scholes option-valuation model, and was based on the strike price of $2.83, the stock price at issuance of $2.66, the ten-year contractual term of the warrants, a risk-free interest rate of 2.22%, expected volatility of 80.22% and 0% expected dividend yield.

As of December 31, 2020, warrants to purchase 176,679 shares of common stock issued to the Lender and its affiliates had not been exercised and were still outstanding. These warrants expire in May 2029.

Note 10 - Commitments and Contingencies

12 Months Ended

Dec. 31, 2020

Commitments and Contingencies Disclosure [Text Block]

10. Commitments and Contingencies

Litigation

From time to time the Company may be involved in legal proceedings arising in the ordinary course of business. The Company does not have contingent liabilities established for any litigation matters.

Note 11 - Stockholders' Equity

12 Months Ended

Dec. 31, 2020

Stockholders' Equity Note Disclosure [Text Block]

11. Stockholders’ Equity

Common Stock

2020 Registered Direct Offerings

On July 23, 2020, the Company completed a registered direct offering in which it issued and sold 9,433,962 shares of its common stock at a price of $1.06 per share. The total net proceeds from this offering were approximately $10.0 million, after deducting estimated expenses payable by the Company of $49,000. No underwriter or placement agent participated in the offering.

On December 11, 2020, the Company completed a registered direct offering in which it issued and sold 8,333,333 shares of its common stock at a price of $1.20 per share. The total net proceeds from this offering were approximately $9.9 million, after deducting estimated expenses payable by the Company of $51,000. No underwriter or placement agent participated in the offering.

ATM Agreement

On June 21, 2016, the Company entered into a Controlled Equity Offering^SM Sales Agreement, or the ATM Agreement, with Cantor Fitzgerald & Co., or Cantor, as agent, pursuant to which the Company may offer and sell, from time to time through Cantor, shares of the Company’s common stock, or the Common Stock having an aggregate offering price of up to $40.0 million, or the Shares. On May 9, 2019, the Company increased the aggregate offering price of shares of the Company’s common stock which may be offered and sold under the ATM Agreement by $40.0 million, for a total of $80.0 million, or the Shares. The offering of Shares pursuant to the ATM Agreement will terminate upon the earlier of (a) the sale of all of the Shares subject to the ATM Agreement or (b) the termination of the ATM Agreement by Cantor or the Company, as permitted therein. The Company will pay Cantor a commission rate in the low single digits on the aggregate gross proceeds from each sale of Shares and have agreed to provide Cantor with customary indemnification and contribution rights.

During the year ended December 31, 2020, the Company issued and sold 876,800 shares of common stock pursuant to the ATM Agreement, for which the Company received net proceeds of approximately $1.4 million. During the year ended December 31, 2019, the Company issued and sold 500,000 shares of common stock pursuant to the ATM Agreement, for which the Company received net proceeds of approximately $1.2 million, after deducting commissions, fees and expenses of $32,000. During the year ended December 31, 2018, the Company issued and sold an aggregate of 4.4 million shares of common stock pursuant to the ATM Agreement, for which the Company received net proceeds of approximately $16.8 million, after deducting commissions, fees and expenses of $0.4 million.

As of December 31, 2020, the Company had the ability to offer and sell shares of the Company’s common stock having an aggregate offering price of up to $43.8 million under the ATM Agreement.

Subsequent to December 31, 2020, the Company received total net proceeds of approximately $28.9 million pursuant to an underwriting agreement, dated January 19, 2021, relating to the underwritten public offering of approximately 16.7 million shares of the Company’s common stock, and $7.4 million through the issuance and sale of the Company’s common stock pursuant to the ATM Agreement. See Note 17 “Subsequent Events” for additional information.

Stock Plans

2011 Equity Incentive Plan

In January 2011, the Board of Directors adopted, and the Company’s stockholders approved, the 2011 Equity Incentive Plan, or 2011 EIP. The initial aggregate number of shares of the Company’s common stock that were issuable pursuant to stock awards under the 2011 EIP was approximately 1.9 million shares. The number of shares of common stock reserved for issuance under the 2011 EIP automatically increased on January 1 of each year, starting on January 1, 2012 and continuing through January 1, 2020, by 4% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or such lesser number of shares of common stock as determined by the Board of Directors.

As of June 16, 2020, no more awards may be granted under the 2011 Equity Incentive Plan, or the 2011 EIP, although all outstanding stock options and other stock awards previously granted under the 2011 EIP will continue to remain subject to the terms of the 2011 EIP.

2020 Equity Incentive Plan

On June 16, 2020, at the 2020 Annual Meeting of Stockholders of the Company, the Company’s stockholders, upon the recommendation of the Company’s Board of Directors, approved the Company’s 2020 Equity Incentive Plan, or the 2020 EIP.

The initial aggregate number of shares of the Company’s common stock issuable pursuant to stock awards under the 2020 EIP was 5,500,000 shares. In addition, the share reserve will be increased by the number of returning shares, if any, as such shares become available from time to time under the 2011 EIP, for an additional number of shares not to exceed 14,892,170 shares. The term of any option granted under the 2020 EIP is determined on the date of grant but shall not be longer than 10 years. The Company issues new shares for settlement of vested restricted stock units and exercises of stock options. The Company does not have a policy of purchasing its shares relating to its stock-based programs.

Amended and Restated 2011 Employee Stock Purchase Plan

Additionally, on June 16, 2020, the Company’s stockholders, upon the recommendation of the Company’s Board of Directors, approved the Amended and Restated 2011 Employee Stock Purchase Plan, or the Amended ESPP, which increased the aggregate number of shares of the Company’s common stock reserved for issuance under the 2011 Employee Stock Purchase Plan, or ESPP, to 4,900,000 shares, subject to adjustment for certain changes in the Company’s capitalization, and removed the “evergreen” provision from the ESPP.

In the year ended December 31, 2020, there were 340,128 shares issued under the Amended ESPP. The weighted average fair value of shares issued under the Amended ESPP in 2020, 2019 and 2018 was $1.09, $2.33 and $1.51 per share, respectively. As of December 31, 2020, there were 4,754,323 shares available for future grant under the Amended ESPP.

Note 12 - Stock-based Compensation

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement [Text Block]

12. Stock-Based Compensation

The Company recorded total stock-based compensation expense for stock options, stock awards and the Amended ESPP as follows (in thousands):

	December 31, 2020		December 31, 2019		December 31, 2018
Cost of goods sold	$	123	$	260	$	358
Research and development		764		920		1,970
Selling, general and administrative		3,537		3,877		2,840
Total	$	4,424	$	5,057	$	5,168

The following table summarizes restricted stock unit activity under the Company’s Equity Incentive Plans:

				Weighted
	Number of			*Average*
	*Restricted*			Grant Date
	Stock Units			Fair Value
Restricted stock units outstanding, January 1, 2019		—		$	—
Granted		1,029,085			2.53
Vested		—			—
Forfeited		(40,440	)		2.54
Restricted stock units outstanding, December 31, 2019		988,645		$	2.53
Granted		908,300			1.30
Vested		(304,810	)		2.53
Forfeited		(194,152	)		2.16
Restricted stock units outstanding, December 31, 2020		1,397,983		$	1.79

The following table summarizes option activity under the Company’s Equity Incentive Plans:

	Number of Stock Options Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
								(in thousands)
December 31, 2019		12,648,739		$	3.47
Granted		1,816,596			1.30
Forfeited		(610,518	)		2.38
Expired		(1,041,795	)		3.68
Exercised		—			—
December 31, 2020		12,813,022		$	3.20		6.1	$	298
Vested and exercisable options—December 31, 2020		9,536,806		$	3.66		5.2	$	—
Vested and expected to vest—December 31, 2020		12,813,022		$	3.20		6.1	$	298

As of December 31, 2020, there were 6,012,971 shares available for future grant under the 2020 EIP.

Additional information regarding the Company’s stock options outstanding and vested and exercisable as of December 31, 2020 is summarized below:

			Options Outstanding						Options Vested and Exercisable
Exercise Prices			Number of Stock Options Outstanding		Weighted-Average Remaining Contractual Life (Years)		Weighted-Average Exercise Price per Share		Shares Subject to Stock Options		Weighted-Average Exercise Price per Share
$0.84	-	$1.31		752,276		9.2	$	0.84		—	$	—
$1.43	-	$2.15		2,549,458		7.8	$	1.88		1,148,695	$	2.00
$2.19	-	$3.29		5,216,124		6.7	$	2.69		4,174,021	$	2.71
$3.30	-	$4.95		2,481,883		4.3	$	3.51		2,400,809	$	3.51
$5.31	-	$7.97		1,286,781		2.7	$	5.75		1,286,781	$	5.75
$8.18	-	$12.27		526,500		3.1	$	10.28		526,500	$	10.28
				12,813,022		6.1	$	3.20		9,536,806	$	3.66

The weighted average grant-date fair value of options granted during the years ended December 31, 2020, 2019 and 2018 was $0.92, $1.83 and $1.62 per share, respectively. As of December 31, 2020, total stock-based compensation expense related to unvested options to be recognized in future periods was $3.8 million which is expected to be recognized over a weighted-average period of 2.1 years. The grant date fair value of shares vested during the years ended December 31, 2020, 2019 and 2018 was $3.6 million, $4.4 million and $4.9 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2020, 2019 and 2018 was $0.0 million, $0.1 million and $0.2 million, respectively.

The Company used the following assumptions to calculate the fair value of each employee stock option:

	Year Ended December 31,
	2020				2019				2018
Expected term (in years)			6.2				6.0				5.9
Risk-free interest rate		0.4%	-	1.5%		1.5%	-	2.5%		2.5%	-	3.1%
Expected volatility			83%				85%				83%
Expected dividend rate			0%				0%				0%

Note 13 - Net Loss Per Share of Common Stock

12 Months Ended

Dec. 31, 2020

Earnings Per Share [Text Block]

13. Net Loss per Share of Common Stock

The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, options to purchase common stock, restricted stock units and warrants to purchase common stock were considered to be common stock equivalents. In periods with a reported net loss, common stock equivalents are excluded from the calculation of diluted net loss per share of common stock if their effect is antidilutive.

The following outstanding shares of common stock equivalents were excluded from the computation of diluted net loss per share of common stock for the periods presented because including them would have been antidilutive:

	Year Ended December 31,
	2020		2019		2018
ESPP, RSUs and stock options to purchase common stock		14,541,005		13,798,797		11,797,960
Common stock warrants		176,679		176,679		—

Note 14 - Accrued Liabilities

12 Months Ended

Dec. 31, 2020

Accounts Payable and Accrued Liabilities Disclosure [Text Block]

14. Accrued Liabilities

Accrued liabilities consist of the following (in thousands):

	December 31,
	2020		2019
Accrued compensation and employee benefits	$	3,293	$	3,796
Inventory and other contract manufacturing accruals		137		752
Other accrued liabilities		1,460		980
Total accrued liabilities	$	4,890	$	5,528

Note 15 - 401(k) Plan

12 Months Ended

Dec. 31, 2020

Retirement Benefits [Text Block]

15. 401(k) Plan

The Company sponsors a 401(k) plan that stipulates that eligible employees can elect to contribute to the 401(k) plan, subject to certain limitations. Pursuant to the 401(k) plan, the Company makes a matching contribution of up to 4% of the related compensation. Under the vesting schedule, employees have ownership in the matching employer contributions based on the number of years of vesting service completed. Company contributions were $0.5 million, $0.5 million, and $0.3 million for the years ended December 31, 2020, 2019 and 2018, respectively.

The entire disclosure for retirement benefits.

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=118257860&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section S99
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
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Note 16 - Income Taxes

12 Months Ended

Dec. 31, 2020

Income Tax Disclosure [Text Block]

16. Income Taxes

The Company recorded a provision for income taxes of $4.0 thousand, $3.0 thousand and $2.0 thousand during the years ended December 31, 2020, 2019 and 2018, respectively.

Net deferred tax assets as of December 31, 2020 and 2019 consist of the following (in thousands):

	December 31, 2020			December 31, 2019
Deferred tax assets:
Accruals and other	$	4,136		$	3,672
Research credits		7,275			7,275
Net operating loss carryforward		65,274			52,361
Section 59(e) R&D expenditures		7,473			8,933
Deferred revenue		20,848			21,324
Total deferred tax assets		105,006			93,565
Valuation allowance		(105,006	)		(93,565	)
Net deferred tax assets	$	—		$	—

Reconciliations of the statutory federal income tax to the Company’s effective tax during the years ended December 31, 2020, 2019 and 2018 are as follows (in thousands):

	Year Ended December 31,
	2020			2019			2018
Tax at statutory federal rate	$	(8,486	)	$	(11,180	)	$	(9,901	)
State tax—net of federal benefit		(3,587	)		(2,538	)		(792	)
General business credits		—			—			(500	)
Stock options		636			800			1,048
Other		—			7			295
Change in valuation allowance		11,441			12,914			9,852
Provision for income taxes	$	4		$	3		$	2

ASC 740 requires that the tax benefit of net operating losses, temporary differences and credit carryforwards be recorded as an asset to the extent that management assesses that realization is “more likely than not.” Realization of deferred tax assets is dependent on future taxable income, if any, the timing and the amount of which are uncertain. Accordingly, the deferred tax assets have been fully offset by a valuation allowance. The valuation allowance increased by $11.4 million, $12.9 million and $9.9 million during the years ended December 31, 2020, 2019 and 2018, respectively.

As of December 31, 2020, the Company had federal net operating loss carryforwards of $264.4 million, of which $114.9 million federal net operating losses generated before January 1, 2018 will begin to expire in 2029. Federal net operating losses of $149.5 million generated from 2018 to 2020 will carryforward indefinitely but are subject to the 80% taxable income limitation. As of December 31, 2020, the Company had state net operating loss carryforwards of $141.5 million, which begin to expire in 2028.

As of December 31, 2020, the Company had federal research credit carryovers of $6.5 million, which begin to expire in 2026. As of December 31, 2020, the Company had state research credit carryovers of $4.0 million, which will carryforward indefinitely.

Under Section 382 of the Internal Revenue Code of 1986, as amended, if a corporation undergoes an “ownership change,” generally defined as a greater than 50% change (by value) in its equity ownership over a three year period, the corporation’s ability to use its pre-change net operating loss carryforwards and other pre-change tax attributes, such as research credits, to offset its post-change income may be limited. Based on an analysis performed by the Company as of December 31, 2013, it was determined that two ownership changes have occurred since inception of the Company. The first ownership change occurred in 2006 at the time of the Series A financing and, as a result of the change, $1.4 million in federal and state net operating loss carryforwards will expire unutilized. In addition, $26 thousand in federal and state research and development credits will expire unutilized. The second ownership change occurred in July 2013 at the time of the underwritten public offering; however, the Company believes the resulting annual imposed limitation on use of pre-change tax attributes is sufficiently high that the limit itself will not result in unutilized pre-change tax attributes.

Uncertain Tax Positions

A reconciliation of the beginning and ending balances of the unrecognized tax benefits during the years ended December 31, 2020, 2019 and 2018 is as follows (in thousands):

	Year Ended December 31,
	2020		2019		2018
Unrecognized benefit—beginning of period	$	2,635	$	2,635	$	2,365
Gross increases—prior period tax positions		—		—		57
Gross increases—current period tax positions		—		—		213
Unrecognized benefit—end of period	$	2,635	$	2,635	$	2,635

The entire amount of the unrecognized tax benefits would not impact the Company’s effective tax rate if recognized.

There were no accrued interest or penalties related to unrecognized tax benefits in the years ended December 31, 2020, 2019 and 2018. The Company files income tax returns in the United States, California, and other states. The tax years 2005 through 2014, and 2016 through 2020, remain open in all jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other foreign jurisdictions. The Company does not anticipate any significant changes within 12 months of this reporting date of its uncertain tax positions.

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References + Details

Note 17 - Subsequent Event

12 Months Ended

Dec. 31, 2020

Subsequent Events [Text Block]

17. Subsequent Events

On January 22, 2021, the Company completed an underwritten public offering in which the Company issued and sold 14,500,000 shares of our common stock to the underwriter at a price of $1.7625 per share. On January 27, 2021, the underwriters exercised their option in full and purchased an additional 2,175,000 shares at a price of $1.7625 per share. The total net proceeds from this offering of an aggregate 16,675,000 shares were approximately $28.9 million. This underwritten public offering was made pursuant to a Registration Statement on Form S-3 (No. 333-239156), which was initially filed by the Company with the Securities and Exchange Commission, or SEC, on June 12, 2020 and declared effective by the SEC on July 8, 2020.

Subsequent to December 31, 2020, the Company issued and sold approximately 3.0 million additional shares of common stock and received additional net proceeds of approximately $7.4 million, after deducting fees and expenses, under the ATM Agreement. As of March 4, 2021, the Company may offer and sell shares of the Company’s common stock having an aggregate offering price of up to $36.2 million under the ATM Agreement.

Schedule II - Valuation and Qualifying Accounts

12 Months Ended

Dec. 31, 2020

SEC Schedule, 12-09, Schedule of Valuation and Qualifying Accounts Disclosure [Text Block]

SCHEDULE II: VALUATION AND QUALIFYING ACCOUNTS
(in thousands)

			Additions
	*Balance at*		*Charged as a*					*Balance at*
	*Beginning of*		*Reduction to*					*End of*
Description	*Period*		*Revenue*		Deductions*			*Period*
Sales & return allowances, discounts, chargebacks and rebates:
Year ended December 31, 2020	$	161	$	645	$	(138	)	$	668
Year ended December 31, 2019	$	—	$	201	$	(40	)	$	161
Year ended December 31, 2018	$	—	$	—	$	—		$	—

* Deductions to sales discounts and allowances relate to discounts or allowances actually taken or paid.

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2020

Accounting Policies [Abstract]

Business Description of Entity [Policy Text Block]

The Company

AcelRx is a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for use in medically supervised settings. DSUVIA®(known as DZUVEO^TM in Europe) and Zalviso® areboth focused on the treatment of acute pain, and each utilize sufentanil, delivered via a non-invasive route of sublingual administration, exclusively for use in medically supervised settings. On November 2, 2018, the U.S. Food and Drug Administration, or FDA, approved DSUVIA for use in adults in a certified medically supervised healthcare setting, such as hospitals, surgical centers, and emergency departments, for the management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. The commercial launch of DSUVIA in the United States occurred in the first quarter of 2019. In June 2018, the European Commission, or EC, granted marketing approval of DZUVEO for the treatment of patients with moderate-to-severe acute pain in medically monitored settings. AcelRx is further developing a distribution capability and commercial organization to continue to market and sell DSUVIA in the United States. In geographies where AcelRx decides not to commercialize products by itself, the Company may seek to out-license commercialization rights. The Company currently intends to commercialize and promote DSUVIA/DZUVEO outside the United States with one or more strategic partners, although it has not yet entered into any such arrangement. The timing of the resubmission of the Zalviso new drug application, or NDA, is in part dependent upon the finalization of the FDA’s new opioid approval guidelines and process. AcelRx intends to seek regulatory approval for Zalviso in the United States and, if successful, potentially promote Zalviso either by itself or with strategic partners. Zalviso is approved in Europe and will be commercialized by Grünenthal GmbH, or Grünenthal, through May 2021 (see Termination of Grünenthal Amended Agreements below).

The Company has incurred recurring operating losses and negative cash flows from operating activities since inception. Although Zalviso was approved for sale in Europe on September 18, 2015, the Company sold the majority of the royalty rights and certain commercial sales milestones it is entitled to receive under the Amended License Agreement (defined below) with Grünenthal to PDL BioPharma, Inc., or PDL, in a transaction referred to as the Royalty Monetization. In consideration of the termination of the Amended License Agreement, under the Royalty Monetization, the Company must use commercially reasonable efforts to negotiate a replacement license agreement with a third party. The Company expects to continue to incur operating losses and negative cash flows until such time as DSUVIA has gained market acceptance and generated significant revenues.

DSUVIA/DZUVEO

DSUVIA, known as DZUVEO in Europe, approved by the FDA in November 2018 and granted marketing approval by the EC in June 2018, is indicated for use in adults in a certified medically supervised healthcare setting, such as hospitals, surgical centers, and emergency departments, for the management of acute pain severe enough to require an opioid analgesic and for which alternative treatments are inadequate. DSUVIA was designed to provide rapid analgesia via a non-invasive route and to eliminate dosing errors associated with IV administration. DSUVIA is a single-strength solid dosage form administered sublingually via a single-dose applicator, or SDA, by healthcare professionals. Sufentanil is an opioid analgesic currently marketed for intravenous, or IV, and epidural anesthesia and analgesia. The sufentanil pharmacokinetic profile when delivered sublingually avoids the high peak plasma levels and short duration of action observed with IV administration.

DSUVIA was approved with a Risk Evaluation and Mitigation Strategy, or REMS, which restricts distribution to certified medically supervised healthcare settings in order to prevent respiratory depression resulting from accidental exposure. DSUVIA is only distributed to facilities certified in the DSUVIA REMS program following attestation by an authorized representative to comply with appropriate dispensing and use restrictions of DSUVIA. To become certified, a healthcare setting is required to train their healthcare professionals on the proper use of DSUVIA and have the ability to manage respiratory depression. DSUVIA is not available in retail pharmacies or for outpatient use. As part of the REMS program, the Company monitors distribution and audits wholesalers’ data, evaluates proper usage within the healthcare settings and monitors for any diversion and abuse. AcelRx will de-certify healthcare settings that are non-compliant with the REMS program.

Promotion Agreement

On March 15, 2020, the Company entered into the Agreement and Plan of Merger (as amended on May 27, 2020 and May 29, 2020, the Merger Agreement) and a Co-Promotion Agreement, or the Co-Promotion Agreement, with Tetraphase Pharmaceuticals, Inc., or Tetraphase, to co-promote DSUVIA and Tetraphases’s XERAVA™ (eravacycline). On June 4, 2020, Tetraphase terminated the Merger Agreement pursuant to its terms and paid AcelRx a termination fee . Net of the termination fee, the Company incurred charges of approximately $1.1 million in connection with the Merger Agreement. On July 28, 2020, Tetraphase was acquired by La Jolla Pharmaceutical Company, or La Jolla. On October 1, 2020, the Company entered into a Promotion Agreement, or the Promotion Agreement, with La Jolla and Tetraphase, effective as of September 30, 2020, pursuant to which the Company, La Jolla and Tetraphase restructured their co-promotion arrangement, with La Jolla agreeing to detail and promote DSUVIA and AcelRx and Tetraphase agreeing to terminate the Co-Promotion Agreement between them.

Under the terms of this agreement, La Jolla is responsible for maintaining compliance under the agreed marketing and promotion plan and achieving a minimum number of sales calls per calendar quarter. The Company will not detail and promote XERAVA™ (eravacycline) under this agreement.

The Promotion Agreement has a two-year term. The Company may terminate the agreement upon 30 days’ notice. After one year, La Jolla may terminate the agreement upon 30 days’ notice and may do so earlier in the event the Company undergoes a change of control and change in management. The Company pay La Jolla a revenue share on net sales of DSUVIA in the sales territories covered by the Promotion Agreement, other than sales to certain excluded accounts. These sales territories do not overlap with the territories covered by the Company’s sales force. If La Jolla fails to meet its detailing requirements in a given calendar quarter, it will pay the Company a royalty on net sales of XERAVA in the United States during such quarter.

There were no material revenues or expenses related to the Promotion Agreement in the year ended December 31, 2020.

Distribution Agreement

On July 17, 2020, the Company entered into a distribution agreement, or the Distribution Agreement, with Zimmer Biomet Dental, or ZB Dental, pursuant to which ZB Dental obtained the exclusive right to promote, market, sell, and arrange to distribute DSUVIA in the United States to clinicians, dentists, surgeons and other licensed health care practitioners that perform dental (including specialty dental), oral-maxillofacial, cranio-maxillofacial or oral surgery procedures, or Professionals, and their respective institutions and facilities that are permitted to use DSUVIA.

ZB Dental’s distribution rights are non-exclusive for crossover ambulatory surgery centers and certain government customers, and do not extend to ambulatory care centers outside the class of trade or into hospitals. ZB Dental will conduct any distribution activities in a manner consistent with DSUVIA’s FDA-approved indication and REMS program, and within the parameters established in the Distribution Agreement. ZB Dental has the right to sublicense its distribution rights to its qualified marketing partners but may not otherwise sublicense its distribution rights to any third party without our prior written consent.

There were no material revenues or expenses related to the Distribution Agreement in the year ended December 31, 2020.

Zalviso

Zalviso delivers 15 mcg sufentanil sublingually through a non-invasive delivery route via a pre-programmed, patient-controlled analgesia, or PCA, system. Zalviso is approved in Europe and is in late-stage development in the United States. The Company had initially submitted to the FDA an NDA seeking approval for Zalviso in September 2013 but received a complete response letter, or CRL, on July 25, 2014. Subsequently, the FDA requested an additional clinical study, IAP312, designed to evaluate the effectiveness of changes made to the functionality and usability of the Zalviso device and to take into account comments from the FDA on the study protocol. In the IAP312 study, for which top-line results were announced in August 2017, Zalviso met safety, satisfaction and device usability expectations. These results will supplement the three Phase 3 trials already completed in the Zalviso NDA resubmission.

Termination of Grünenthal Amended Agreements

On December 16, 2013, AcelRx and Grünenthal entered into a Collaboration and License Agreement, or the License Agreement, which was amended effective July 17, 2015 and September 20, 2016, or the Amended License Agreement, which granted Grünenthal rights to commercialize the Zalviso PCA system, or the Product, in the 28 European Union, or EU, member states, at the time of the agreement, plus Switzerland, Liechtenstein, Iceland, Norway and Australia (collectively, the Territory) for human use in pain treatment within, or dispensed by, hospitals, hospices, nursing homes and other medically supervised settings, (collectively, the Field). In September 2015, the EC granted marketing approval for the marketing authorization application, or MAA, previously submitted to the EMA, for Zalviso for the management of acute moderate-to-severe post-operative pain in adult patients. On December 16, 2013, AcelRx and Grünenthal, entered into a Manufacture and Supply Agreement, or the MSA, and together with the License Agreement, the Agreements. Under the MSA, the Company exclusively manufactured and supplied the Product to Grünenthal for the Field in the Territory. On July 22, 2015, the Company and Grünenthal amended the MSA, or the Amended MSA, effective as of July 17, 2015. The Amended MSA and the Amended License Agreement are referred to as the Grünenthal Agreements.

On May 18, 2020, the Company received a notice from Grünenthal that it had exercised its right to terminate the Grünenthal Agreements, effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory, a right it had under the Grünenthal Agreements. The rights to market and sell Zalviso in the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia, or the Territory, will revert back to the Company in May 2021.

Except as the context otherwise requires, when we refer to "we," "our," "us," the "Company" or "AcelRx" in this document, we mean AcelRx Pharmaceuticals, Inc., and its consolidated subsidiary. “DZUVEO” is a trademark, and “ACELRX”, “DSUVIA” and “Zalviso” are registered trademarks, all owned by AcelRx Pharmaceuticals, Inc. This report also contains trademarks and trade names that are the property of their respective owners.

Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation

The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and the accompanying notes. Actual results could differ from those estimates.

Reclassification, Comparability Adjustment [Policy Text Block]

Reclassifications

Certain prior year amounts in the Consolidated Financial Statements have been reclassified to conform to the current year's presentation. In particular, the amounts reported in the Consolidated Balance Sheets as tax receivable and long-term tax receivable have been reclassified to prepaid expenses and other current assets, and other assets, respectively, at December 31, 2019. In addition, the amounts reported in the Consolidated Statements of Cash Flows as inventory impairment have been reclassified to other for the years ended December 31, 2019 and 2018, the amounts reported as tax receivable and other assets have been reclassified to prepaid expenses and other assets for the year ended December 31, 2019, and the amount reported as deferred rent has been reclassified to prepaid expenses and other assets for the year ended December 31, 2018.

Consolidation, Policy [Policy Text Block]

Principles of Consolidation

The Consolidated Financial Statements include the accounts of the Company and its wholly owned subsidiary, ARPI LLC, which was formed in September 2015 for the sole purpose of facilitating the Royalty Monetization with PDL of the expected royalty stream and milestone payments due from the sales of Zalviso in the European Union by its commercial partner, Grünenthal, pursuant to the Amended License Agreement. All intercompany accounts and transactions have been eliminated in consolidation. Refer to Note 8 “Liability Related to Sale of Future Royalties” for additional information.

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying notes. Management evaluates its estimates on an ongoing basis including critical accounting policies. Estimates are based on historical experience and on various other market-specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.

Cash, Cash Equivalents, and Marketable Securities [Policy Text Block]

Cash, Cash Equivalents and Short-Term Investments

The Company considers all highly liquid investments with an original maturity (at date of purchase) of three months or less to be cash equivalents. Cash and cash equivalents consist of cash on deposit with banks.

All marketable securities are classified as available-for-sale and consist of commercial paper, U.S. government sponsored enterprise debt securities and corporate debt securities. These securities are carried at estimated fair value, which is based on quoted market prices or observable market inputs of almost identical assets, with unrealized gains and losses included in accumulated other comprehensive income (loss). The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income or expense. The cost of securities sold is based on specific identification. The Company’s investments are subject to a periodic impairment review for other-than-temporary declines in fair value. The Company’s review includes the consideration of the cause of the impairment including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. When the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other-than-temporary, it reduces the carrying value of the security it holds and records a loss in the amount of such decline.

Fair Value Measurement, Policy [Policy Text Block]

Fair Value of Financial Instruments

The Company measures and reports its cash equivalents, investments and financial liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows:

Level I—Unadjusted quoted prices in active markets for identical assets or liabilities;

Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and

Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities.

The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.

Segment Reporting, Policy [Policy Text Block]

Segment Information

The Company operates in a single segment, the development and commercialization of product candidates and products for the treatment of pain. The Company’s product sales revenue consists of sales of DSUVIA in the United States and Zalviso in Europe. The Company’s contract and collaboration revenue consists of non-cash royalty revenue, royalty revenue, and other revenue under the Grünenthal Agreements.

Concentration Risk, Credit Risk, Policy [Policy Text Block]

Concentration of Risk

The Company invests cash that is currently not being used for operational purposes in accordance with its investment policy in debt securities of U.S. government sponsored agencies, commercial paper and overnight deposits. The Company is exposed to credit risk in the event of default by the institutions holding the cash equivalents and available-for-sale securities to the extent recorded on the Consolidated Balance Sheets.

The Company relies on a single third-party supplier for the supply of sufentanil, the active pharmaceutical ingredient in DSUVIA and Zalviso, and various sole-source third-party contract manufacturer organizations to manufacture the DSUVIA SDA.

DSUVIA sales are concentrated with the DoD and in a limited number of wholesalers. Zalviso has been sold in Europe by Grünenthal, who terminated the Grünenthal Agreements, effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory. Revenue and accounts receivable have been concentrated with these customers.

	Year Ended December 31,
Percent of Total Revenue	2020			2019			2018
Grünenthal		74.0	%		83.6	%		61.1	%
DoD		16.9	%		0	%		38.9	%
Wholesaler A		3.9	%		0	%		0	%
Wholesaler B		2.1	%		7.5	%		0	%
Wholesaler C		1.2	%		5.7	%		0	%
All others		1.9	%		3.2	%		0	%

Receivable [Policy Text Block]

Accounts Receivable, net

The need for a bad debt allowance is evaluated each reporting period based on the Company’s assessment of the credit worthiness of its customers or any other potential circumstances that could result in bad debt.

The Company has not experienced any losses with respect to the collection of its accounts receivable and believes that the entire accounts receivable balance as of December 31, 2020 is collectible.

	As of December 31,
Percent of Accounts Receivable, Net	2020			2019
Customer A		79	%		0	%
Customer B		12	%		15	%
Customer C		6	%		5	%
Customer D		0	%		72	%
All Others		3	%		8	%

Inventory, Policy [Policy Text Block]

Inventories, net

Inventories are valued at the lower of cost or net realizable value. Cost is determined using the first-in, first-out method for all inventories. Inventory includes the cost of the active pharmaceutical ingredients, or API, raw materials and third-party contract manufacturing and packaging services. Indirect overhead costs associated with production and distribution are allocated to the appropriate cost pool and then absorbed into inventory based on the units produced or distributed, assuming normal capacity, in the applicable period. Indirect overhead costs in excess of normal capacity are recorded as period costs in the period incurred. DSUVIA was approved by the FDA in November 2018. Prior to FDA approval, all manufacturing costs for DSUVIA were expensed to research and development. Upon FDA approval, manufacturing costs for DSUVIA manufactured for commercial sale have been capitalized.

The Company's policy is to write down inventory that has become obsolete, inventory that has a cost basis in excess of its expected net realizable value and inventory in excess of expected requirements. The Company periodically evaluates the carrying value of inventory on hand for potential excess amount over demand using the same lower of cost or net realizable value approach as that used to value the inventory.

Property, Plant and Equipment, Policy [Policy Text Block]

Property and Equipment, net

Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation is calculated using the straight-line method over the estimated useful lives of the assets, generally three to five years. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvements or the remaining lease term. Expenditures for repairs and maintenance, which do not extend the useful life of the property and equipment, are expensed as incurred. Upon retirement, the asset cost and related accumulated depreciation are relieved from the accompanying Consolidated Balance Sheets. Gains and losses associated with dispositions are reflected as a component of interest income and other income, net in the accompanying Consolidated Statements of Comprehensive Loss.

Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]

Impairment of Long-Lived Assets

The Company periodically assesses the impairment of long-lived assets and, if indicators of asset impairment exist, the Company assesses the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through an analysis of the undiscounted future expected operating cash flows. If impairment is indicated, the Company records the amount of such impairment for the excess of the carrying value of the asset over its estimated fair value. For example, if the Company is not successful in its commercialization of DSUVIA, and if approved, Zalviso, purchased equipment and manufacturing-related facility improvements the Company has made at its contract manufacturers could become impaired. The Company may determine that it is no longer probable that the Company will realize the future economic benefit associated with the costs of these assets through future manufacturing activities, and if so, the Company would record an impairment charge associated with these assets.

Contingent Put Option, Policy [Policy Text Block]

Contingent put option

The contingent put option associated with the Company’s Loan Agreement with Oxford is recorded as a liability. Changes in the fair value of the contingent put option are recognized as interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. For further discussion, see Note 6 “Long-Term Debt”.

Lessee, Leases [Policy Text Block]

Leases

In February 2016, the FASB issued Accounting Standards Update, or ASU, No. 2016-02, Leases (Topic 842), to enhance the transparency and comparability of financial reporting related to leasing arrangements. The Company adopted the standard effective January 1, 2019.

At the inception of an arrangement, the Company determines whether the arrangement is, or contains, a lease based on the unique facts and circumstances present. Operating lease liabilities and their corresponding right-of-use assets are recorded based on the present value of lease payments over the expected lease term. The interest rate implicit in lease contracts is typically not readily determinable. As such, the Company utilizes its incremental borrowing rate, which is the rate incurred to borrow on a collateralized basis over a similar term an amount equal to the lease payments in a similar economic environment. Certain adjustments to the right-of-use asset may be required for items such as initial direct costs paid or incentives received.

Lease expense is recognized over the expected term on a straight-line basis. Operating leases are recognized on the Consolidated Balance Sheet as operating lease right-of-use assets, operating lease liabilities current and operating lease liabilities non-current. As a result, the Company no longer recognizes deferred rent on the Consolidated Balance Sheet.

Revenue [Policy Text Block]

Revenue from Contracts with Customers

The Company follows the provisions of Accounting Standards Codification, or ASC, Topic 606, Revenue from Contracts with Customers. This guidance provides a unified model to determine how revenue is recognized. The Company recognizes revenue upon transfer of control of promised products or services to customers in an amount that reflects the consideration the Company expects to receive in exchange for those products or services. The Company sells its products primarily through wholesale distributors.

In determining the appropriate amount of revenue to be recognized as it fulfills its obligations under its agreements, the Company performs the following steps: (i) identification of the promised goods or services in the contract; (ii) determination of whether the promised goods or services are performance obligations, including whether they are distinct in the context of the contract; (iii) measurement of the transaction price, including the constraint on variable consideration; (iv) allocation of the transaction price to the performance obligations based on estimated selling prices; and (v) recognition of revenue when (or as) the Company satisfies each performance obligation.

Product sales revenue

The Company sells its product primarily through distributors. Revenues from product sales are recognized when distributors obtain control of the Company’s product, which occurs at a point in time, upon delivery to such distributors. These distributors subsequently resell the product to certified medically supervised healthcare settings. In addition to distribution agreements with these customers, the Company enters into arrangements with group purchasing organizations, or GPOs, and other certified medically supervised healthcare settings that provide for privately negotiated discounts with respect to the purchase of its products. For revenue recognition under bill-and-hold arrangements, wherein the customer agrees to buy product from the Company but requests delivery at a later date, the Company deems that control passes to the customer when the product is ready for delivery. The Company recognizes revenue under these types of arrangements when a signed agreement is in place, the transaction is billable, the customer has significant risk and rewards for the product and the ability to direct the asset, the product has been set aside specifically for the customer, and the product cannot be redirected to another customer. Revenue from product sales is recorded at the transaction price, net of estimates for variable consideration consisting of chargebacks, government rebates, returns, distribution fees, GPO fees and product returns. Variable consideration is recorded at the time product sales are recognized resulting in a reduction in product revenue. The amount of variable consideration that is included in the transaction price may be constrained and is included in the net sales price only to the extent that it is probable that a significant reversal in the amount of the cumulative revenue recognized will not occur in a future period. Variable consideration is estimated using the most-likely amount method, which is the single-most likely outcome under a contract and is typically at the stated contractual rate. Where appropriate, these estimates take into consideration a range of possible outcomes that are probability-weighted in accordance with the expected value method under ASC Topic 606 for relevant factors. These factors include current contractual and statutory requirements, specific known market events and trends, industry data, and/or forecasted customer buying and payment patterns. Actual amounts of consideration ultimately received may differ from the Company’s estimates. If actual results vary materially from the Company’s estimates, the Company will adjust these estimates, which will affect revenue from product sales and earnings in the period such estimates are adjusted. These estimates include:

Chargebacks – The Company’s customers subsequently resell its product to qualified healthcare providers. In addition to distribution agreements with customers, the Company enters into arrangements with qualified healthcare providers that provide for chargebacks and discounts with respect to the purchase of our product. Chargebacks represent the estimated obligations resulting from contractual commitments to sell product to qualified healthcare providers at prices lower than the list prices charged to customers who directly purchase the product from the Company. Customers charge the Company for the difference between what they pay for the product and the ultimate selling price to the qualified healthcare providers. These reserves are established in the same period that the related revenue is recognized, resulting in a reduction of product revenue and accounts receivable. Chargeback amounts are determined at the time of resale to the qualified healthcare providers by customers, and the Company issues credits for such amounts generally within a few weeks of the customer's notification to the Company of the resale. Reserves for chargebacks consists of credits that the Company expects to issue for units that remain in the distribution channel inventories at each reporting period end that the Company expects will be sold to the qualified healthcare providers, and chargebacks for units that the Company’s customers have sold to the qualified healthcare providers, but for which credits have not been issued.

Government Rebates – The Company is subject to discount obligations under state Medicaid programs. The Company estimates its Medicaid rebates, and reserves are recorded in the same period the related product revenue is recognized, resulting in a reduction of product revenue and the establishment of a current liability that is included in accrued liabilities on the Consolidated Balance Sheet.

Returns – The Company allows its distributors to return product for credit 6 months prior to, and up to 12 months after, the product expiration date. As such, there may be a significant period of time between the time the product is shipped and the time the credit is issued on returned product.

Distribution Fees - Distribution fees include fees paid to certain customers for sales order management, data and distribution services. Distribution fees are recorded as a reduction of revenue in the period the related product revenue is recognized.

GPO Fees – The Company pays administrative fees to GPOs for services and access to data. These fees are based on contracted terms and are paid after the quarter in which the product was purchased by the GPOs’ members.

Trade Discounts and Allowances - The Company provides its customers with discounts which include early payment incentives that are explicitly stated in its contracts and are recorded as a reduction of revenue in the period the related product revenue is recognized.

The Company believes its estimated allowances for chargebacks, government rebates and product returns require a high degree of judgment and are subject to change based on its limited experience and certain quantitative and qualitative factors. The Company believes its estimated allowances for distribution fees, GPO fees and trade discounts and allowances do not require a high degree of judgment because the amounts are settled within a relatively short period of time. The Company will continue to assess its estimates of variable consideration as it accumulates additional historical data and will adjust these estimates accordingly. Changes in product revenue allowance estimates could materially affect the Company’s results of operations and financial position.

Contract and other collaboration revenue

The Company generates revenue from collaboration agreements. These agreements typically include payments for upfront signing or license fees, cost reimbursements for development and manufacturing services, milestone payments, product sales, and royalties on licensee’s future product sales. Product sales related revenue under these collaboration agreements is classified as product sales revenue, while other revenue generated from collaboration agreements is classified as contract and other collaboration revenue.

The Company entered into award contracts with U.S. Department of Defense, or the DoD, to support the development of DSUVIA. These contracts provided for the reimbursement of qualified expenses for research and development activities. Revenue under these arrangements was recognized when the related qualified research expenses were incurred. The Company was entitled to reimbursement of overhead costs associated with the study costs under the DoD arrangements. The Company estimated this overhead rate by utilizing forecasted expenditures. Final reimbursable overhead expenses were dependent on direct labor and direct reimbursable expenses throughout the life of each contract, which increased or decreased based on actual expenses incurred.

Performance Obligations

A performance obligation is a promise in a contract to transfer a distinct good or service to the customer and is the unit of account in ASC Topic 606. The Company’s performance obligations include delivering product to its distributors, commercialization license rights, development services, services associated with the regulatory approval process, joint steering committee services, demonstration devices, manufacturing services, material rights for discounts on manufacturing services, and product supply.

The Company has optional additional items in contracts, which are considered marketing offers and are accounted for as separate contracts when the customer elects such options. Arrangements that include a promise for future commercial product supply and optional research and development services at the customer’s or the Company’s discretion are generally considered as options. The Company assesses if these options provide a material right to the licensee and if so, such material rights are accounted for as separate performance obligations. If the Company is entitled to additional payments when the customer exercises these options, any additional payments are recorded in revenue when the customer obtains control of the goods or services.

Transaction Price

The Company has both fixed and variable consideration. Variable consideration for product revenue is described as Net product sales in the Consolidated Statements of Comprehensive Loss. For collaboration agreements, non-refundable upfront fees and product supply selling prices are considered fixed, while milestone payments are identified as variable consideration when determining the transaction price. Funding of research and development activities is considered variable until such costs are reimbursed at which point, they are considered fixed. The Company allocates the total transaction price to each performance obligation based on the relative estimated standalone selling prices of the promised goods or services for each performance obligation.

At the inception of each arrangement that includes milestone payments, the Company evaluates whether the milestones are considered probable of being achieved and estimates the amount to be included in the transaction price using the most likely amount method. If it is probable that a significant revenue reversal would not occur, the value of the associated milestone (such as a regulatory submission by the Company) is included in the transaction price. Milestone payments that are not within the control of the Company, such as approvals from regulators, are not considered probable of being achieved until those approvals are received.

For arrangements that include sales-based royalties, including milestone payments based on the level of sales, and the license is deemed to be the predominant item to which the royalties relate, the Company recognizes revenue at the later of (a) when the related sales occur, or (b) when the performance obligation to which some or all of the royalty has been allocated has been satisfied (or partially satisfied).

Allocation of Consideration

As part of the accounting for collaboration arrangements, the Company must develop assumptions that require judgment to determine the stand-alone selling price of each performance obligation identified in the contract. Estimated selling prices for license rights and material rights for discounts on manufacturing services are calculated using an income approach model and can include the following key assumptions: the development timeline, sales forecasts, costs of product sales, commercialization expenses, discount rate, the time which the manufacturing services are expected to be performed, and probabilities of technical and regulatory success. For all other performance obligations, the Company uses a cost- plus margin approach.

Timing of Recognition

Significant management judgment is required to determine the level of effort required under collaboration arrangements and the period over which the Company expects to complete its performance obligations under the arrangement. The Company estimates the performance period or measure of progress at the inception of the arrangement and re-evaluates it each reporting period. This re-evaluation may shorten or lengthen the period over which revenue is recognized. Changes to these estimates are recorded on a cumulative catch up basis. If the Company cannot reasonably estimate when its performance obligations either are completed or become inconsequential, then revenue recognition is deferred until the Company can reasonably make such estimates. Revenue is then recognized over the remaining estimated period of performance using the cumulative catch-up method. Revenue is recognized for products at a point in time when control of the product is transferred to the customer in an amount that reflects the consideration the Company expects to be entitled to in exchange for those product sales, which is typically once the product physically arrives at the customer, and for licenses of functional intellectual property at the point in time the customer can use and benefit from the license. For performance obligations that are services, revenue is recognized over time proportionate to the costs that the Company has incurred to perform the services using the cost-to-cost input method.

Cost of Goods and Service [Policy Text Block]

Cost of Goods Sold

Cost of goods sold for product revenue includes third party manufacturing costs, shipping and handling costs, and indirect overhead costs associated with production and distribution which are allocated to the appropriate cost pool and recognized when revenue is recognized. Indirect overhead costs in excess of normal capacity are recorded as period costs in the period incurred.

Under the Grünenthal Agreements, the Company sold Zalviso to Grünenthal at predetermined, contractual transfer prices that were less than the direct costs of manufacturing and recognized indirect costs as period costs where they were in excess of normal capacity and not recoverable on a lower of cost or net realizable value basis. Cost of goods sold for Zalviso shipped to Grünenthal includes the inventory costs of API, third-party contract manufacturing costs, packaging and distribution costs, shipping, handling and storage costs, depreciation and costs of the employees involved with production.

Research and Development Expense, Policy [Policy Text Block]

Research and Development Expenses

Research and development costs are charged to expense when incurred. Research and development expenses include salaries, employee benefits, including stock-based compensation, consultant fees, laboratory supplies, costs associated with clinical trials and manufacturing, including contract research organization fees, other professional services and allocations of corporate costs. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events.

Advertising Cost [Policy Text Block]

Advertising Expenses

Advertising costs are expensed as incurred. Advertising expenses were $0.5 million, $1.1 million and $0.5 million for the years ended December 31, 2020, 2019 and 2018, respectively, and are included in selling, general and administrative expenses in the Consolidated Statements of Comprehensive Loss.

Share-based Payment Arrangement [Policy Text Block]

Stock-Based Compensation

Compensation expense for all stock-based payment awards made to employees and directors, including employee stock options and restricted stock units related to the 2011 Equity Incentive Plan, or 2011 EIP, and employee share purchases related to the 2011 Employee Stock Purchase Plan, or ESPP, is based on estimated fair values at grant date. The Company determines the grant date fair value of the awards using the Black-Scholes option-pricing model and generally recognizes the fair value as stock-based compensation expense on a straight-line basis over the vesting period of the respective awards.

The Black-Scholes option pricing model requires inputs such as expected term, expected volatility and risk-free interest rate. These inputs are subjective and generally require significant analysis and judgment to develop. The expected term, which represents the period of time that options granted are expected to be outstanding, is derived by analyzing the historical experience of similar awards, giving consideration to the contractual terms of the stock‑based awards, vesting schedules and expectations of future employee behavior. Expected volatilities are estimated using the historical stock price performance over the expected term of the option, which are adjusted as necessary for any other factors which may reasonably affect the volatility of AcelRx’s stock in the future. The risk‑free interest rate is based on the U.S. Treasury yield in effect at the time of the grant for the expected term of the award. The Company recognizes forfeitures when they occur and does not anticipate paying dividends in the near future.

Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block]

Restructuring Costs

The Company's restructuring costs consist of employee termination benefit costs. Liabilities for costs associated with the cost reduction plan are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the Company notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the future service period.

On March 16, 2020, in connection with entering into the Co-Promotion Agreement, the Company initiated a reduction in headcount, designed to eliminate the overlap with the Tetraphase commercial team in order to more efficiently commercialize DSUVIA alongside the Tetraphase commercial team and reduce operating expenses. The Company eliminated 30 positions, primarily within the commercial organization. For the year ended December 31, 2020, the Company incurred and paid $0.5 million in employee termination benefits related to this restructuring.

The headcount reduction was completed in the first quarter of 2020. No additional expenses are anticipated in connection with this cost reduction plan.

Interest Expense, Policy [Policy Text Block]

Non-Cash Interest Income (Expense) on Liability Related to Sale of Future Royalties

In September 2015, the Company sold certain royalty and milestone payment rights from the sales of Zalviso in the European Union by Grünenthal, pursuant to the Grünenthal Agreements, to PDL for gross proceeds of $65.0 million. Grünenthal terminated the Grünenthal Agreements effective November 13, 2020. The terms of the Grünenthal Agreements were extended to May 2021 to enable Grünenthal to sell down its Zalviso inventory. The rights to market and sell Zalviso in the Territory, will revert back to the Company in May 2021.

Under the Royalty Monetization, the Company has a continuing obligation to use commercially reasonable efforts to negotiate a replacement license agreement, or New Arrangement. Under the relevant accounting guidance, because of the Company’s significant continuing involvement, the Royalty Monetization is accounted for as a liability that is being amortized using the effective interest method over the life of the arrangement. In order to determine the amortization of the liability, the Company is required to estimate the total amount of future royalty and milestone payments to be received by ARPI LLC and payments made to PDL, up to a capped amount of $195.0 million, over the life of the arrangement. The aggregate future estimated royalty and milestone payments (subject to the capped amount), less the $61.2 million of net proceeds the Company received, are amortized as interest expense over the life of the liability. Consequently, the Company imputes interest on the unamortized portion of the liability and records interest expense, or interest income, as these estimates are updated.

There are a number of factors that could materially affect the amount and timing of royalty and milestone payments from Zalviso in Europe, most of which are not within the Company’s control. Such factors include, but are not limited to, the success of any future sales and promotion of Zalviso under any New Arrangement, if achieved; changing standards of care; the introduction of competing products; manufacturing or other delays; intellectual property matters; adverse events that result in governmental health authority imposed restrictions on the use of Zalviso; significant changes in foreign exchange rates as the royalties remitted to ARPI LLC are made in U.S. dollars; and other events or circumstances that could result in reduced royalty payments from European sales of Zalviso, all of which may result in a reduction of non-cash royalty revenues and the non-cash interest expense over the life of the Royalty Monetization. Conversely, if sales of Zalviso in Europe are greater than expected, the non-cash royalty revenues and the non-cash interest expense recorded by the Company would be greater over the term of the Royalty Monetization. The Company periodically assesses the expected royalty and milestone payments using a combination of historical results, internal projections and forecasts from external sources. To the extent such payments are greater or less than the Company’s initial estimates or the timing of such payments is materially different than its original estimates, the Company will prospectively adjust the amortization of the liability and the effective interest rate. Because estimated sales forecasts and payments may vary over the life of the Royalty Monetization, the Company may be required to recognize interest income as the imputed interest rate is adjusted prospectively to reflect the revised effective interest rate over the term of the Royalty Monetization.

The Company records non-cash royalty revenues and non-cash interest income (expense), net, within its Consolidated Statements of Comprehensive Loss over the term of the Royalty Monetization.

When the expected payments under the Royalty Monetization are lower than the gross proceeds of $65.0 million received, the Company defers recognition of any probable contingent gain until the Royalty Monetization liability expires.

Comprehensive Income, Policy [Policy Text Block]

Comprehensive Loss

Comprehensive loss is comprised of net loss and other comprehensive income (loss) and is disclosed in the Consolidated Statements of Comprehensive Loss. For the Company, other comprehensive income (loss) consists of changes in unrealized gains and losses on the Company’s investments.

Income Tax, Policy [Policy Text Block]

Income Taxes

Deferred tax assets and liabilities are measured based on differences between the financial reporting and tax basis of assets and liabilities using enacted rates and laws that are expected to be in effect when the differences are expected to reverse. The Company records a valuation allowance for the full amount of deferred assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.

Earnings Per Share, Policy [Policy Text Block]

Net Loss per Share of Common Stock

The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, convertible preferred stock, options to purchase common stock, restricted stock subject to repurchase, restricted stock units, warrants to purchase convertible preferred stock and warrants to purchase common stock were considered to be common stock equivalents. In periods with a reported net loss, such common stock equivalents are excluded from the calculation of diluted net loss per share of common stock if their effect is antidilutive. For additional information regarding the net loss per share, see Note 13 “Net Loss per Share of Common Stock”.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Issued Accounting Pronouncements

In June 2016, the FASB issued ASU 2016-13, “Financial Instruments – Credit Losses: Measurement of Credit Losses on Financial Instruments,” or ASU 2016-13. ASU 2016-13 replaces the incurred loss impairment model in current GAAP with a model that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to determine credit loss estimates. ASU 2016-13 is effective for the Company beginning January 1, 2023, with early adoption allowed beginning January 1, 2020. In May 2019, the FASB issued ASU 2019-05, “Financial Instruments – Credit Losses,” or ASU 2019-05, to allow entities to irrevocably elect the fair value option for certain financial assets previously measured at amortized cost upon adoption of the new credit losses standard. The new effective dates and transition align with those of ASU 2016-13. Management is currently assessing the date of adoption and the impact ASU 2016-13 and ASU 2019-05 will have on the Company, but it does not anticipate adoption of these new standards to have a material impact on the Company’s financial position, results of operations or cash flows.

In March 2020, the FASB issued ASU 2020-04, “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The amendments provide optional guidance for a limited time to ease the potential burden in accounting for reference rate reform. The new guidance provides optional expedients and exceptions for applying U.S. GAAP to contracts, hedging relationships and other transactions affected by reference rate reform if certain criteria are met. The amendments apply only to contracts and hedging relationships that reference LIBOR or another reference rate expected to be discontinued due to reference rate reform. These amendments are effective immediately and may be applied prospectively to contract modifications made and hedging relationships entered into or evaluated on or before December 31, 2022. The FASB also issued ASU No. 2021-01, “Reference Rate Reform (Topic 848): Scope” in January 2021. It clarifies that certain optional expedients and exceptions in Topic 848 apply to derivatives that are affected by the discounting transition. The amendments in this ASU affect the guidance in ASU 2020-04 and are effective in the same timeframe as ASU 2020-04. The Company is currently evaluating its contracts and the optional expedients and exceptions provided by the new standard, but it does not anticipate its adoption to have a material impact on the Company’s financial position, results of operations or cash flows.

Note 1 - Organization and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2020

Schedules of Concentration of Risk, by Risk Factor [Table Text Block]

	Year Ended December 31,
Percent of Total Revenue	2020			2019			2018
Grünenthal		74.0	%		83.6	%		61.1	%
DoD		16.9	%		0	%		38.9	%
Wholesaler A		3.9	%		0	%		0	%
Wholesaler B		2.1	%		7.5	%		0	%
Wholesaler C		1.2	%		5.7	%		0	%
All others		1.9	%		3.2	%		0	%

	As of December 31,
Percent of Accounts Receivable, Net	2020			2019
Customer A		79	%		0	%
Customer B		12	%		15	%
Customer C		6	%		5	%
Customer D		0	%		72	%
All Others		3	%		8	%

Note 2 - Investments and Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2020

Cash, Cash Equivalents and Investments [Table Text Block]

	As of December 31, 2020
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	5,181	$	—	$	—	$	5,181
Money market funds		3,996		—		—		3,996
Commercial paper		18,097		—		—		18,097
Total cash and cash equivalents		27,274		—		—		27,274

Short-term investments:
U.S. government agency securities		5,818		—		—		5,818
Commercial paper		9,794		—		—		9,794
Total short-term investments		15,612		—		—		15,612
Total cash, cash equivalents and short-term investments	$	42,886	$	—	$	—	$	42,886

	As of December 31, 2019
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	1,957	$	—	$	—	$	1,957
Money market funds		598		—		—		598
Commercial paper		12,129		—		—		12,129
Total cash and cash equivalents		14,684		—		—		14,684

Short-term investments:
U.S. government agency securities		14,268		—		—		14,268
Commercial paper		27,131		—		—		27,131
Corporate debt securities		10,054		—		—		10,054
Total short-term investments		51,453		—		—		51,453
Total cash, cash equivalents and short-term investments	$	66,137	$	—	$	—	$	66,137

Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]

	As of December 31, 2020
	Fair Value		Level I		Level II		Level III
Assets
Money market funds	$	3,996	$	3,996	$	—	$	—
U.S. government agency securities		5,818		—		5,818		—
Commercial paper		27,891		—		27,891		—
Total assets measured at fair value	$	37,705	$	3,996	$	33,709	$	—

Liabilities
Contingent put option liability	$	246	$	—	$	—	$	246
Total liabilities measured at fair value	$	246	$	—	$	—	$	246

	As of December 31, 2019
	Fair Value		Level I		Level II		Level III
Assets
Money market funds	$	598	$	598	$	—	$	—
U.S. government agency securities		14,268		—		14,268		—
Commercial paper		39,260		—		39,260		—
Corporate debt securities		10,054		—		10,054		—
Total assets measured at fair value	$	64,180	$	598	$	63,582	$	—

Liabilities
Contingent put option liability	$	437	$	—	$	—	$	437
Total liabilities measured at fair value	$	437	$	—	$	—	$	437

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Year Ended December 31, 2020
Fair value—beginning of period	$	437
Change in fair value of contingent put option associated with the Loan Agreement		(191	)
Fair value—end of period	$	246

	Year Ended December 31, 2019
Fair value—beginning of period	$	121
Change in fair value of contingent put option associated with the Loan Agreement		437
Change in fair value of contingent put option associated with the Prior Agreement		(121	)
Fair value—end of period	$	437

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Note 3 - Inventories, Net (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Inventory, Current [Table Text Block]

	As of December 31,
	2020		2019
Raw materials	$	257	$	1,153
Work-in-process		30		593
Finished goods		1,339		1,549
Inventories	$	1,626	$	3,295

Note 4 - Property and Equipment, Net (Tables)

12 Months Ended

Dec. 31, 2020

Property, Plant and Equipment [Table Text Block]

	As of December 31,
	2020			2019
Laboratory equipment	$	4,406		$	4,389
Leasehold improvements		4,616			4,616
Computer equipment and software		1,724			1,749
Construction in process		14,101			11,949
Tooling		1,109			1,109
Furniture and fixtures		292			292

		26,248			24,104
Less accumulated depreciation and amortization		(10,589	)		(9,552	)
Property and equipment, net	$	15,659		$	14,552

Note 5 - Revenue From Contracts With Customers (Tables)

12 Months Ended

Dec. 31, 2020

Disaggregation of Revenue [Table Text Block]

	December 31,
	2020		2019		2018
Product sales:
DSUVIA	$	1,409	$	377	$	—
Zalviso		1,112		1,453		825
Total product sales		2,521		1,830		825
Contract and other collaboration:
DoD Contract revenue		—		—		838
Non-cash royalty revenue related to Royalty Monetization (See Note 8)		242		312		289
Royalty revenue		81		104		96
Other revenue		2,572		43		103
Total revenues from contract and other collaboration		2,895		459		1,326
Total revenue	$	5,416	$	2,289	$	2,151

Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block]

	Balance at Beginning of the Period		Additions		Deductions			Balance at the end of the Period
	(in thousands)
Contract liability:
Deferred revenue – Amended Agreements	$	3,244	$	—	$	(3,195	)	$	49

	Year ended December 31, 2020		Year ended December 31, 2019
Amounts included in contract liabilities at the beginning of the period:
Performance obligations satisfied	$	623	$	315
Performance obligations eliminated upon termination		2,572		—
New activities in the period from performance obligations satisfied:
Performance obligations satisfied		488		1,181
Total revenue from performance obligations satisfied or eliminated	$	3,683	$	1,496

Note 6 - Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Long-term Debt Instruments [Table Text Block]

	As of December 31, 2020
Present value of the face amount of $1.0 million	$	865
Less: current portion		402
Long-term debt, net of current portion	$	463

Schedule of Maturities of Long-term Debt [Table Text Block]

2021	$	10,429
2022		9,647
2023		5,530
Total payments		25,606
Less amount representing interest		(2,523	)
Notes payable, gross		23,083
Less: Unamortized portion of EOT Fee		(524	)
Less: Unamortized discount on notes payable		(684	)
Long-term debt		21,875
Less current portion		(8,735	)
Long-term debt, net of current portion	$	13,140

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

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Note 7 - Leases (Tables)

12 Months Ended

Dec. 31, 2020

Lease, Cost [Table Text Block]

	Year ended December 31, 2020			Year ended December 31, 2019
Operating lease costs	$	1,360		$	1,360
Sublease income		(598	)		(596	)
Net lease costs	$	762		$	764

	Year ended December 31, 2020		Year ended December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows used for operating leases	$	1,268	$	1,084
Supplemental non-cash disclosures of lease activities:
Transfer of tenant improvement allowance to sublease	$	—	$	242
Right-of-use assets obtained in exchange for new operating lease liabilities	$	—	$	4,730

	December 31,			December 31,
	2020			2019
Weighted-average remaining lease term – operating leases (years)	3.1			4.1
Weighted-average remaining discount rate – operating leases		11.7	%		11.7	%

Lessee, Operating Lease, Liability, Maturity [Table Text Block]

Year:
2021	$	1,504
2022		1,445
2023		1,386
2024		116
Total future minimum lease payments		4,451
Less imputed interest		(727	)
Total	$	3,724

Reported as:
Operating lease liabilities	$	1,118
Operating lease liabilities, net of current portion		2,606
Total lease liability	$	3,724

Lessee, Operating Sublease, to Be Received, Maturity [Table Text Block]

Year:
2021	$	610
2022		629
2023		648
2024		54
Total future minimum sublease payments	$	1,941

Reported as:
Prepaid expenses and other current assets	$	96
Other assets		258
Total rent receivable	$	354

Note 8 - Liability Related to Sale of Future Royalties (Tables)

12 Months Ended

Dec. 31, 2020

Other Liabilities [Table Text Block]

	Year ended December 31, 2020			Period from inception to December 31, 2020
Liability related to sale of future royalties — beginning balance	$	92,035		$	—
Proceeds from sale of future royalties		—			61,184
Non-cash royalty revenue		(254	)		(938	)
Non-cash interest (income) expense recognized		(3,310	)		28,225
Liability related to sale of future royalties as of December 31, 2020		88,471			88,471
Less: current portion		(106	)		(106	)
Liability related to sale of future royalties — net of current portion	$	88,365		$	88,365

Note 12 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2020

Share-based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block]

	December 31, 2020		December 31, 2019		December 31, 2018
Cost of goods sold	$	123	$	260	$	358
Research and development		764		920		1,970
Selling, general and administrative		3,537		3,877		2,840
Total	$	4,424	$	5,057	$	5,168

Share-based Payment Arrangement, Restricted Stock and Restricted Stock Unit, Activity [Table Text Block]

				Weighted
	Number of			*Average*
	*Restricted*			Grant Date
	Stock Units			Fair Value
Restricted stock units outstanding, January 1, 2019		—		$	—
Granted		1,029,085			2.53
Vested		—			—
Forfeited		(40,440	)		2.54
Restricted stock units outstanding, December 31, 2019		988,645		$	2.53
Granted		908,300			1.30
Vested		(304,810	)		2.53
Forfeited		(194,152	)		2.16
Restricted stock units outstanding, December 31, 2020		1,397,983		$	1.79

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Stock Options Outstanding			Weighted- Average Exercise Price		Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
								(in thousands)
December 31, 2019		12,648,739		$	3.47
Granted		1,816,596			1.30
Forfeited		(610,518	)		2.38
Expired		(1,041,795	)		3.68
Exercised		—			—
December 31, 2020		12,813,022		$	3.20		6.1	$	298
Vested and exercisable options—December 31, 2020		9,536,806		$	3.66		5.2	$	—
Vested and expected to vest—December 31, 2020		12,813,022		$	3.20		6.1	$	298

Schedule of Share-based Compensation, Stock Options Outstanding and Exercisable Activity [Table Text Block]

			Options Outstanding						Options Vested and Exercisable
Exercise Prices			Number of Stock Options Outstanding		Weighted-Average Remaining Contractual Life (Years)		Weighted-Average Exercise Price per Share		Shares Subject to Stock Options		Weighted-Average Exercise Price per Share
$0.84	-	$1.31		752,276		9.2	$	0.84		—	$	—
$1.43	-	$2.15		2,549,458		7.8	$	1.88		1,148,695	$	2.00
$2.19	-	$3.29		5,216,124		6.7	$	2.69		4,174,021	$	2.71
$3.30	-	$4.95		2,481,883		4.3	$	3.51		2,400,809	$	3.51
$5.31	-	$7.97		1,286,781		2.7	$	5.75		1,286,781	$	5.75
$8.18	-	$12.27		526,500		3.1	$	10.28		526,500	$	10.28
				12,813,022		6.1	$	3.20		9,536,806	$	3.66

Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]

	Year Ended December 31,
	2020				2019				2018
Expected term (in years)			6.2				6.0				5.9
Risk-free interest rate		0.4%	-	1.5%		1.5%	-	2.5%		2.5%	-	3.1%
Expected volatility			83%				85%				83%
Expected dividend rate			0%				0%				0%

Note 13 - Net Loss Per Share of Common Stock (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]

	Year Ended December 31,
	2020		2019		2018
ESPP, RSUs and stock options to purchase common stock		14,541,005		13,798,797		11,797,960
Common stock warrants		176,679		176,679		—

Note 14 - Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Accrued Liabilities [Table Text Block]

	December 31,
	2020		2019
Accrued compensation and employee benefits	$	3,293	$	3,796
Inventory and other contract manufacturing accruals		137		752
Other accrued liabilities		1,460		980
Total accrued liabilities	$	4,890	$	5,528

Note 16 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2020

Schedule of Deferred Tax Assets [Table Text Block]

	December 31, 2020			December 31, 2019
Deferred tax assets:
Accruals and other	$	4,136		$	3,672
Research credits		7,275			7,275
Net operating loss carryforward		65,274			52,361
Section 59(e) R&D expenditures		7,473			8,933
Deferred revenue		20,848			21,324
Total deferred tax assets		105,006			93,565
Valuation allowance		(105,006	)		(93,565	)
Net deferred tax assets	$	—		$	—

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	Year Ended December 31,
	2020			2019			2018
Tax at statutory federal rate	$	(8,486	)	$	(11,180	)	$	(9,901	)
State tax—net of federal benefit		(3,587	)		(2,538	)		(792	)
General business credits		—			—			(500	)
Stock options		636			800			1,048
Other		—			7			295
Change in valuation allowance		11,441			12,914			9,852
Provision for income taxes	$	4		$	3		$	2

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	Year Ended December 31,
	2020		2019		2018
Unrecognized benefit—beginning of period	$	2,635	$	2,635	$	2,365
Gross increases—prior period tax positions		—		—		57
Gross increases—current period tax positions		—		—		213
Unrecognized benefit—end of period	$	2,635	$	2,635	$	2,635

Schedule II - Valuation and Qualifying Accounts (Tables)

12 Months Ended

Dec. 31, 2020

Valuation Allowances and Reserves [Table Text Block]

			Additions
	*Balance at*		*Charged as a*					*Balance at*
	*Beginning of*		*Reduction to*					*End of*
Description	*Period*		*Revenue*		Deductions*			*Period*
Sales & return allowances, discounts, chargebacks and rebates:
Year ended December 31, 2020	$	161	$	645	$	(138	)	$	668
Year ended December 31, 2019	$	—	$	201	$	(40	)	$	161
Year ended December 31, 2018	$	—	$	—	$	—		$	—

Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) $ in Thousands				1 Months Ended	12 Months Ended			63 Months Ended
	Jun. 04, 2020 USD ($)	Mar. 16, 2020	Sep. 18, 2015 USD ($)	Sep. 30, 2015 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2020 USD ($)
Advertising Expense					$ 500	$ 1,100	$ 500
Restructuring and Related Cost, Number of Positions Eliminated		30
Restructuring Charges, Total					500
Proceeds From Sale of Royalty and Milestone Rights			$ 65,000	$ 65,000
Royalty Arrangment Maximum Payments			$ 195,000	195,000
Net Proceeds from Sale of Future Royalties				$ 61,200	$ 0			$ 61,184
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)					3 years
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)					5 years
Tetraphase [Member]
Merger Agreement, Charges, Net of Termination Fee	$ 1,100

Note 1 - Organization and Summary of Significant Accounting Policies - Concentration of Revenue and Accounts Receivable (Details) - Customer Concentration Risk [Member]	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue Benchmark [Member] \| Grunenthal [Member]
Concentration risk	74.00%	83.60%	61.10%
Revenue Benchmark [Member] \| DoD [Member]
Concentration risk	16.90%	0.00%	38.90%
Revenue Benchmark [Member] \| Wholesaler A [Member]
Concentration risk	3.90%	0.00%	0.00%
Revenue Benchmark [Member] \| Wholesaler B [Member]
Concentration risk	2.10%	7.50%	0.00%
Revenue Benchmark [Member] \| Wholesaler C [Member]
Concentration risk	1.20%	5.70%	0.00%
Revenue Benchmark [Member] \| All Others [Member]
Concentration risk	1.90%	3.20%	0.00%
Accounts Receivable [Member] \| Customer A [Member]
Concentration risk	79.00%	0.00%
Accounts Receivable [Member] \| Customer B [Member]
Concentration risk	12.00%	15.00%
Accounts Receivable [Member] \| Customer C [Member]
Concentration risk	6.00%	5.00%
Accounts Receivable [Member] \| Customer D [Member]
Concentration risk	0.00%	72.00%
Accounts Receivable [Member] \| All Others [Member]
Concentration risk	3.00%	8.00%

Note 2 - Investments and Fair Value Measurement (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Debt Securities, Available-for-sale, Realized Gain (Loss), Total	$ 0	$ 0	$ 0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Total	0	0
OCI, Debt Securities, Available-for-Sale, Transfer from Held-to-Maturity, Gain (Loss), before Adjustment, after Tax	$ 0	$ 0

Note 2 - Investments and Fair Value Measurement - Summary of Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Amortized Cost	$ 42,886	$ 66,137
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	42,886	66,137
Cash and Cash Equivalents [Member]
Amortized Cost	27,274	14,684
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	27,274	14,684
Cash and Cash Equivalents [Member] \| Cash [Member]
Amortized Cost	5,181	1,957
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	5,181	1,957
Cash and Cash Equivalents [Member] \| Money Market Funds [Member]
Amortized Cost	3,996	598
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	3,996	598
Cash and Cash Equivalents [Member] \| Commercial Paper [Member]
Amortized Cost	18,097	12,129
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	18,097	12,129
Cash and Cash Equivalents [Member] \| U.S. Government Agency Securities [Member]
Amortized Cost		14,268
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		14,268
Marketable Securities [Member]
Amortized Cost	15,612	51,453
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	15,612	51,453
Marketable Securities [Member] \| Commercial Paper [Member]
Amortized Cost	9,794	27,131
Gross Unrealized Gains	0	0
Gross Unrealized Losses	0	0
Fair Value	9,794	27,131
Marketable Securities [Member] \| U.S. Government Agency Securities [Member]
Amortized Cost	5,818
Gross Unrealized Gains	0
Gross Unrealized Losses	0
Fair Value	$ 5,818
Marketable Securities [Member] \| Corporate Debt Securities [Member]
Amortized Cost		10,054
Gross Unrealized Gains		0
Gross Unrealized Losses		0
Fair Value		$ 10,054

Note 2 - Investments and Fair Value Measurement - Fair Value of Financial Assets and Liabilities by Level Within Fair Value Hierarchy (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Assets, fair value	$ 37,705	$ 64,180
Liabilities, fair value	246	437
Contingent Put Option Liability [Member]
Liabilities, fair value	246	437
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	3,996	598
Liabilities, fair value	0	0
Fair Value, Inputs, Level 1 [Member] \| Contingent Put Option Liability [Member]
Liabilities, fair value	0	0
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	33,709	63,582
Liabilities, fair value	0	0
Fair Value, Inputs, Level 2 [Member] \| Contingent Put Option Liability [Member]
Liabilities, fair value	0	0
Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
Liabilities, fair value	246	437
Fair Value, Inputs, Level 3 [Member] \| Contingent Put Option Liability [Member]
Liabilities, fair value	246	437
Money Market Funds [Member]
Assets, fair value	3,996	598
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value	3,996	598
Money Market Funds [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	0	0
Money Market Funds [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
U.S. Government Agency Securities [Member]
Assets, fair value	5,818	14,268
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value	0	0
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	5,818	14,268
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value	0	0
Commercial Paper [Member]
Assets, fair value	27,891	39,260
Commercial Paper [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value	0	0
Commercial Paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	27,891	39,260
Commercial Paper [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value	$ 0	0
Corporate Debt Securities [Member]
Assets, fair value		10,054
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value		0
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value		10,054
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value		$ 0

Note 2 - Investments and Fair Value Measurement - Summary of Changes in Fair Value of Level III Financial Liabilities (Details) - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Fair value, Beginning of period	$ 437	$ 121
Change in fair value of contingent put option associated with the Loan Agreement	(191)	(121)
Change in fair value of contingent put option associated with the Loan Agreement		437
Fair value, End of period	$ 246	$ 437

Note 3 - Inventories, Net (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Inventory Write-down	$ 0.7	$ 1.0
Terminated Amended Agreements [Member]
Inventory Write-down	0.3
DSUVIA [Member]
Inventory Write-down	$ 0.4

Note 3 - Inventories, Net - Inventory Components (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Raw materials	$ 257	$ 1,153
Work-in-process	30	593
Finished goods	1,339	1,549
Inventories	$ 1,626	$ 3,295

Note 4 - Property and Equipment, Net (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Depreciation, Total	$ 1.1	$ 0.9	$ 0.5

Note 4 - Property and Equipment, Net - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Property and Equipment, Gross	$ 26,248	$ 24,104
Less accumulated depreciation and amortization	(10,589)	(9,552)
Property and equipment, net	15,659	14,552
Laboratory Equipment [Member]
Property and Equipment, Gross	4,406	4,389
Leasehold Improvements [Member]
Property and Equipment, Gross	4,616	4,616
Computer Equipment and Software [Member]
Property and Equipment, Gross	1,724	1,749
Construction in Progress [Member]
Property and Equipment, Gross	14,101	11,949
Tooling [Member]
Property and Equipment, Gross	1,109	1,109
Furniture and Fixtures [Member]
Property and Equipment, Gross	$ 292	$ 292

Note 5 - Revenue From Contracts With Customers (Details Textual) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Jul. 17, 2015	May 11, 2015
Government Contract Receivable					$ 17,000
Deferred Revenue, Noncurrent, Total			$ 3,100
Deferred Revenue, Current, Total			300
Amended License Agreement [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount, Based On Efforts And Targets				$ 194,500
Contract with Customer, Liability, Liability Eliminated		$ 2,572	$ 0
Amended License Agreement [Member] \| Based upon Successful Regulatory and Product Development Efforts [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount, Based On Efforts And Targets				28,500
Amended License Agreement [Member] \| Based upon Net Sales Target Achievements [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount, Based On Efforts And Targets				$ 166,000
ZALVISO [Member]
Contract with Customer, Liability, Liability Eliminated	$ 2,600

Note 5 - Revenue From Contracts With Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue	$ 5,416	$ 2,289	$ 2,151
DSUVIA [Member]
Revenue	1,409	377	0
ZALVISO [Member]
Revenue	1,112	1,453	825
Product [Member]
Revenue	2,521	1,830	825
Department of Defense [Member]
Revenue	0	0	838
Non-cash Royalty [Member]
Revenue	242	312	289
Royalty [Member]
Revenue	81	104	96
Contract and Other Revenue [Member]
Revenue	2,572	43	103
Contract and Other Collaboration [Member]
Revenue	$ 2,895	$ 459	$ 1,326

Amount, including tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value-added and excise.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
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-Paragraph 22
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 22
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e8736-108599

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 4
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=121604090&loc=SL49130543-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 42
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9054-108599

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 280
-SubTopic 10
-Section 50
-Paragraph 40
-URI http://asc.fasb.org/extlink&oid=120311839&loc=d3e9031-108599

Reference 11: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 924
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SAB Topic 11.L)
-URI http://asc.fasb.org/extlink&oid=6472922&loc=d3e499488-122856

Note 5 - Revenue From Contracts With Customers - Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	May 31, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenue		$ 5,416	$ 2,289	$ 2,151
ZALVISO [Member]
Contract Liabilities: Deferred Revenue		3,244
Contract Liabilities: Deferred Revenue, Additions		0
Contract Liabilities: Deferred Revenue, Deductions		(3,195)
Contract Liabilities: Deferred Revenue		49	3,244
Amounts included in contract liabilities at the beginning of the period: Performance obligations eliminated upon termination	$ 2,600
Revenue		1,112	1,453	$ 825
Amended License Agreement [Member]
Amounts included in contract liabilities at the beginning of the period: Performance obligations satisfied		623	315
Amounts included in contract liabilities at the beginning of the period: Performance obligations eliminated upon termination		2,572	0
New activities in the period from performance obligations satisfied: Performance obligations satisfied		488	1,181
Revenue		$ 3,683	$ 1,496

Note 6 - Long-term Debt (Details Textual) - USD ($)			12 Months Ended
Note 6 - Long-term Debt (Details Textual) - USD ($)	Aug. 01, 2019	May 30, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Repayments of Long-term Debt, Total			$ 4,667,000	$ 3,470,000	$ 7,718,000
Interest Expense, Total			3,305,000	2,535,000	2,217,000
Long-term Debt, Total			21,875,000
Amortization of Debt Discount (Premium)			1,069,000	712,000	613,000
Leasehold Improvements [Member]
Capital Leases, Balance Sheet, Assets by Major Class, Net, Total			1,700,000
Warrant In Connection with Oxford Finance Loan Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares)		176,679
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 2.83
Loan Agreement with Oxford Finance LLC [Member]
Long-term Debt, Total			21,000,000.0	24,200,000
Loan Agreement with Oxford Finance LLC [Member]
Repayments of Long-term Debt, Total		$ 8,900,000
Debt Instrument, Face Amount		25,000,000.0
Proceeds from Debt, Net of Issuance Costs and Repayment of Debt		$ 15,900,000
Debt Instrument, Interest Rate, Base Percentage		2.50%
Debt Instrument, Final Payment, Percentage of Aggregate Principal Amount		5.00%
Prepayment Charge, Percentage of Outstanding Balance, After May 30, 2020, Before May 30, 2021		1.50%
Prepayment Charge, Percentage of Outstanding Balance, After May 30,2021		1.00%
Debt Instrument, Covenant, Minimum Required Unrestircted Cash		$ 5,000,000.0
Debt Instrument, Minimum Indebtedness Amount with Acceleration Right		250,000
Loan Default Events, Trigger of Negative Impact of Government Approvals and Judgments		$ 500,000
Debt Instrument, Default Additional Interest Rate		5.00%
Fair Value of Contingent Put Option, Liability			200,000
Interest Expense, Debt, Total			3,200,000	1,900,000
Amortization of Debt Discount (Premium)			900,000	600,000
Loan Agreement with Oxford Finance LLC [Member] \| Minimum [Member]
Net Unrestricted Cash Proceeds, Contingent Threshold for Interest Only Period of Loan		$ 45,000,000.0
Loan Agreement with Oxford Finance LLC [Member] \| London Interbank Offered Rate (LIBOR) [Member]
Debt Instrument, Basis Spread on Variable Rate		6.75%
Hercules Loan and Security Agreement [Member]
Repayments of Long-term Debt, Total		$ 8,900,000
Long-term Debt, Gross		7,400,000
Debt Instrument, Termination Fee		1,300,000
Gain (Loss) on Extinguishment of Debt, Total		$ (200,000)
Interest Expense, Total			0.0	$ 600,000	$ 2,200,000
Site Readiness Agreement [Member]
Long-term Debt, Total			865,000
Debt Instrument, Periodic Payment, Principal	$ 500,000
Total Obligation Under Leasehold Agreement			$ 800,000
Debt Instrument, Interest Rate, Effective Percentage			14.35%

Note 6 - Long-term Debt - Balance of Future Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Long-term debt	$ 21,875
Less: current portion	8,735	$ 4,630
Long-term debt, net of current portion	13,140	$ 20,517
Site Readiness Agreement [Member]
Long-term debt	865
Less: current portion	402
Long-term debt, net of current portion	$ 463

Note 6 - Long-term Debt - Outstanding Future Payments of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
2021	$ 10,429
2022	9,647
2023	5,530
Total payments	25,606
Less amount representing interest	(2,523)
Notes payable, gross	23,083
Less: Unamortized portion of EOT Fee	(524)
Less: Unamortized discount on notes payable	(684)
Long-term debt	21,875
Less current portion	(8,735)	$ (4,630)
Long-term debt, net of current portion	$ 13,140	$ 20,517

Note 7 - Leases (Details Textual) - USD ($)			1 Months Ended	12 Months Ended
Note 7 - Leases (Details Textual) - USD ($)	Jan. 02, 2019	Dec. 12, 2012	Jun. 30, 2017	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Feb. 16, 2019
Lessee, Operating Lease, Renewal Term (Year)		2 years	6 years
Lessee, Operating Lease, Monthly Rent			$ 100,000
Lessee, Operating Lease, Annual Rent Increase			3.00%
Percentage of Office and Laboratory Space Sublease							47.00%
Lessee, Operating Sublease Monthly Rent	$ 48,000
Lessee, Operating Sublease, Annual Rent Increase	3.00%
Lessee, Operating Sublease, Direct Costs	$ 400,000
Lessee, Operating Sublease, Initial Tenant Incentive Allowance Transfered from Operating Lease	200,000			$ 0	$ 242,000
Increase (Decrease) in Operating Lease Liabilities	$ (24,000)			$ (886,000)	$ (701,000)	$ 0
Lessee, Operating Lease, Notice Period (Month)		18 months
Lessee, Operating Lease, Annual Overhead Fee Payments		$ 200,000

Note 7 - Leases - Operating Lease Costs (Details) - USD ($) $ in Thousands		12 Months Ended
	Jan. 02, 2019	Dec. 31, 2020	Dec. 31, 2019
Operating lease costs		$ 1,360	$ 1,360
Sublease income		(598)	(596)
Net lease costs		762	764
Operating cash flows used for operating leases		1,268	1,084
Lessee, Operating Sublease, Initial Tenant Incentive Allowance Transfered from Operating Lease	$ 200	0	242
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 0	$ 4,730
Weighted-average remaining lease term – operating leases (years) (Year)		3 years 1 month 6 days	4 years 1 month 6 days
Weighted-average remaining discount rate – operating leases		11.70%	11.70%

Note 7 - Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
2021	$ 1,504
2022	1,445
2023	1,386
2024	116
Total future minimum lease payments	4,451
Less imputed interest	(727)
Total	3,724
Operating lease liabilities	1,118	$ 970
Operating lease liabilities, net of current portion	2,606	$ 3,640
Total lease liability	$ 3,724

Note 7 - Leases - Future Minimum Sublease Payments (Details) $ in Thousands	Dec. 31, 2020 USD ($)
2021	$ 610
2022	629
2023	648
2024	54
Total future minimum sublease payments	1,941
Rent receivable	354
Prepaid Expenses and Other Current Assets [Member]
Rent receivable	96
Other Assets [Member]
Rent receivable	$ 258

Note 8 - Liability Related to Sale of Future Royalties (Details Textual) - USD ($) $ / shares in Units, $ in Millions		1 Months Ended	3 Months Ended		6 Months Ended	12 Months Ended
	Sep. 18, 2015	Sep. 30, 2015	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Proceeds From Sale of Royalty and Milestone Rights	$ 65.0	$ 65.0
Royalty Arrangment Maximum Payments	$ 195.0	$ 195.0
Prospective Average Rate for Remaining Term of the Agreement				4.20%
Contingent Gain (Loss) on Royalty Monetization Arrangement			$ 65.0
Effective Interest Over Life of Liability Related to Sale of Future Royalties					0.00%
Net Income (Loss) from Change Estimate on Liability Related to Sale of Future Royalties						$ 8.1
Net Income (Loss) Per Share, Change Estimate on Liability Related to Sale of Future Royalties (in dollars per share)						$ 0.10
Effective Annual Interest Rate						3.60%	1.40%	11.60%
First Four Commercial Milestones [Member]
Percentage of Royalties and Rights Under Agreement	20.00%
Royalties [Member]
Percentage of Royalties and Rights Under Agreement	25.00%
Remaining Commercial and All Development Milestone[Member]
Percentage of Royalties and Rights Under Agreement	100.00%
Commercial Milestones Value	$ 43.5
MAA Approval [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount	15.0
PDL [Member]
Proceeds From Sale of Royalty and Milestone Rights	$ 61.2
Percentage of Royalties and Rights Under Agreement	75.00%
PDL [Member] \| First Four Commercial Milestones [Member]
Percentage of Royalties and Rights Under Agreement	80.00%
Commercial Milestones Value Maximum Amount Available	$ 35.6
AcelRX [Member] \| First Four Commercial Milestones [Member]
Commercial Milestones Value Maximum Amount Available	$ 44.5

Note 8 - Liability Related to Sale of Future Royalties - Activity of Liability Related to Sale of Future Royalties (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended			63 Months Ended
	Sep. 30, 2015	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2020
Liability related to sale of future royalties — beginning balance		$ 92,035			$ 0
Proceeds from sale of future royalties	$ 61,200	0			61,184
Non-cash royalty revenue		(254)			(938)
Non-cash interest (income) expense recognized		(3,310)	$ (1,337)	$ 10,341	28,225
Liability related to sale of future royalties as of December 31, 2020		88,471	92,035		88,471
Less: current portion		(106)	(352)		(106)
Liability related to sale of future royalties — net of current portion		$ 88,365	$ 91,683		$ 88,365

Note 9 - Warrants (Details Textual) - Warrant In Connection with Oxford Finance Loan Agreement [Member] $ in Millions	Dec. 31, 2020 shares	May 30, 2019 USD ($) $ / shares yr shares
Class of Warrant or Right, Number of Securities Called by Warrants or Rights (in shares) \| shares		176,679
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 2.83
Warrants and Rights Outstanding, Term (Year)		10 years
Warrants and Rights Outstanding \| $		$ 0.4
Class of Warrant or Right, Outstanding (in shares) \| shares	176,679
Measurement Input, Exercise Price [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights (in dollars per share)		$ 2.83
Measurement Input, Share Price [Member]
Warrants and Rights Outstanding, Measurement Input (in dollars per share)		2.66
Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input (in dollars per share) \| yr		10
Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input (in dollars per share)		0.0222
Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input (in dollars per share)		0.8022
Measurement Input, Expected Dividend Rate [Member]
Warrants and Rights Outstanding, Measurement Input (in dollars per share)		0

Note 11 - Stockholders' Equity (Details Textual) - USD ($)										1 Months Ended	2 Months Ended	12 Months Ended
	Mar. 04, 2021	Jan. 27, 2021	Jan. 27, 2021	Jan. 22, 2021	Dec. 11, 2020	Jul. 23, 2020	Jun. 16, 2020	May 09, 2019	Jun. 21, 2016	Jan. 31, 2011	Mar. 15, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2011
Proceeds from Issuance of Common Stock												$ 21,337,000	$ 1,233,000	$ 81,525,000
Employee Stock Purchase Plan, Shares Issued, Weighted Average Fair Value (in dollars per share)												$ 1.09	$ 2.33	$ 1.51
2011 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Outstanding (in shares)										1.9
Stock Option Plan Option Reserve Annual Increase as Percentage of Outstanding Shares Allowed															4.00%
The 2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)							5,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)												6,012,971
The 2020 Equity Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares to be Added (in shares)							14,892,170
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period (Year)							10 years
Employee Stock Purchase Plan (ESPP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in shares)							4,900,000					340,128
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)												4,754,323
Private Placement [Member] \| Armistice Capital and Rock Springs Capital [Member]
Stock Issued During Period, Shares, New Issues (in shares)					8,333,333	9,433,962
Shares Issued, Price Per Share (in dollars per share)					$ 1.20	$ 1.06
Proceeds from Issuance of Common Stock					$ 9,900,000	$ 10,000,000.0
Estimated Offering Costs					$ 51,000	$ 49,000
ATM Agreement [Member]
Stock Issued During Period, Shares, New Issues (in shares)												876,800	500,000	4,400,000
Aggregate Offering Price, Maximum								$ 80,000,000.0	$ 40,000,000.0			$ 43,800,000
Aggregate Offering Price, Increase During Period								$ 40,000,000.0
Proceeds from Issuance of Common Stock, Net												$ 1,400,000	$ 1,200,000	$ 16,800,000
Payments of Stock Issuance Costs													$ 32,000	$ 400,000
ATM Agreement [Member] \| Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)											3,000,000.0
Aggregate Offering Price, Maximum	$ 36,200,000
Proceeds from Issuance of Common Stock, Net											$ 7,400,000
Underwritten Public Offering [Member] \| Subsequent Event [Member]
Stock Issued During Period, Shares, New Issues (in shares)		2,175,000	16,675,000	14,500,000
Shares Issued, Price Per Share (in dollars per share)		$ 1.7625	$ 1.7625	$ 1.7625
Proceeds from Issuance of Common Stock, Net			$ 28,900,000

Note 12 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in dollars per share)	$ 0.92	$ 1.83	$ 1.62
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 3,800
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)	2 years 1 month 6 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value	$ 3,600	$ 4,400	$ 4,900
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value	$ 0	$ 100	$ 200
The 2020 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in shares)	6,012,971

Note 12 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Stock-based compensation expense	$ 4,424	$ 5,057	$ 5,168
Cost of Sales [Member]
Stock-based compensation expense	123	260	358
Research and Development Expense [Member]
Stock-based compensation expense	764	920	1,970
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 3,537	$ 3,877	$ 2,840

Note 12 - Stock-based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units (RSUs) [Member] - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Restricted stock units outstanding (in shares)	988,645	0
Restricted stock units weighted average outstanding (in dollars per share)	$ 2.53	$ 0
Granted (in shares)	908,300	1,029,085
Weighted average grant date fair value, granted (in dollars per share)	$ 1.30	$ 2.53
Vested (in shares)	(304,810)	0
Weighted average grant date fair value, vested (in dollars per share)	$ 2.53	$ 0
Forfeited (in shares)	(194,152)	(40,440)
Weighted average grant date fair value, forfeited (in dollars per share)	$ 2.16	$ 2.54
Restricted stock units outstanding (in shares)	1,397,983	988,645
Restricted stock units weighted average outstanding (in dollars per share)	$ 1.79	$ 2.53

Note 12 - Stock-based Compensation - Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) $ / shares shares
Outstanding (in shares) \| shares	12,648,739
Outstanding (in dollars per share) \| $ / shares	$ 3.47
Granted (in shares) \| shares	1,816,596
Granted, weighted-average exercise price (in dollars per share) \| $ / shares	$ 1.30
Forfeited (in shares) \| shares	(610,518)
Forfeited, weighted-average exercise price (in dollars per share) \| $ / shares	$ 2.38
Expired (in shares) \| shares	(1,041,795)
Expired, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.68
Exercised (in shares) \| shares	0
Exercised, weighted-average exercise price (in dollars per share) \| $ / shares	$ 0
Outstanding (in shares) \| shares	12,813,022
Outstanding, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.20
Outstanding, weighted-average remaining contractual life (Year)	6 years 1 month 6 days
Outstanding, aggregate intrinsic value \| $	$ 298
Vested and exercisable options (in shares) \| shares	9,536,806
Vested and exercisable options, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.66
Vested and exercisable options, weighted-average remaining contractual life (Year)	5 years 2 months 12 days
Vested and exercisable options, aggregate intrinsic value \| $	$ 0
Vested and expected to vest (in shares) \| shares	12,813,022
Vested and expected to vest, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.20
Vested and expected to vest, weighted-average remaining contractual life (Year)	6 years 1 month 6 days
Vested and expected to vest, aggregate intrinsic value \| $	$ 298

Note 12 - Stock-based Compensation - Stock Options Outstanding, Vested and Exercisable (Details) - $ / shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019
Number of Stock Options Outstanding (in shares)	12,813,022	12,648,739
Weighted-average Remaining Contractual LIfe (Year)	6 years 1 month 6 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.20	$ 3.47
Shares Subject to Stock Options (in shares)	9,536,806
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.66
Exercise Price Range 1 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	0.84
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 1.31
Number of Stock Options Outstanding (in shares)	752,276
Weighted-average Remaining Contractual LIfe (Year)	9 years 2 months 12 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 0.84
Shares Subject to Stock Options (in shares)	0
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 0
Exercise Price Range 2 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	1.43
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 2.15
Number of Stock Options Outstanding (in shares)	2,549,458
Weighted-average Remaining Contractual LIfe (Year)	7 years 9 months 18 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 1.88
Shares Subject to Stock Options (in shares)	1,148,695
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 2.00
Exercise Price Range 3 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	2.19
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 3.29
Number of Stock Options Outstanding (in shares)	5,216,124
Weighted-average Remaining Contractual LIfe (Year)	6 years 8 months 12 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 2.69
Shares Subject to Stock Options (in shares)	4,174,021
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 2.71
Exercise Price Range 4 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	3.30
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 4.95
Number of Stock Options Outstanding (in shares)	2,481,883
Weighted-average Remaining Contractual LIfe (Year)	4 years 3 months 18 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.51
Shares Subject to Stock Options (in shares)	2,400,809
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.51
Exercise Price Range 5 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	5.31
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 7.97
Number of Stock Options Outstanding (in shares)	1,286,781
Weighted-average Remaining Contractual LIfe (Year)	2 years 8 months 12 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 5.75
Shares Subject to Stock Options (in shares)	1,286,781
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 5.75
Exercise Price Range 6 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	8.18
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 12.27
Number of Stock Options Outstanding (in shares)	526,500
Weighted-average Remaining Contractual LIfe (Year)	3 years 1 month 6 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 10.28
Shares Subject to Stock Options (in shares)	526,500
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 10.28

Note 12 - Stock-based Compensation - Assumptions to Calculate Fair Value of Each Employee Stock Option (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Expected term (Year)	6 years 2 months 12 days	6 years	5 years 10 months 24 days
Expected volatility	83.00%	85.00%	83.00%
Expected dividend rate	0.00%	0.00%	0.00%
Minimum [Member]
Risk-free interest rate	0.40%	1.50%	2.50%
Maximum [Member]
Risk-free interest rate	1.50%	2.50%	3.10%

Note 13 - Net Loss Per Share of Common Stock - Common Stock Excluded From Computation of Diluted Net Loss Per Share (Details) - shares	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
RSU's, ESPP, and Employee Stock Options [Member]
Antidilutive securities (in shares)	14,541,005	13,798,797	11,797,960
Warrant [Member]
Antidilutive securities (in shares)	176,679	176,679	0

Note 14 - Accrued Liabilities - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accrued compensation and employee benefits	$ 3,293	$ 3,796
Inventory and other contract manufacturing accruals	137	752
Other accrued liabilities	1,460	980
Total accrued liabilities	$ 4,890	$ 5,528

Note 15 - 401(k) Plan (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Defined Contribution Plan, Employer Discretionary Contribution Percentage		4.00%
Contributions by Employer to Postemployment Benefit Obligations	$ 0.5	$ 0.5	$ 0.3

Note 16 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income Tax Expense (Benefit), Total	$ 4	$ 3	$ 2
Valuation Allowance, Deferred Tax Asset, Increase (Decrease), Amount	11,400	12,900	9,900
Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued, Total	$ 0	$ 0	$ 0
Open Tax Year	2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2016 2017 2018 2019 2020
Subject to Expiration [Member]
Operating Loss Carryforwards, Total	$ 1,400
Research Tax Credit Carryforward [Member] \| Subject to Expiration [Member]
Tax Credit Carryforward, Amount	26
Domestic Tax Authority [Member]
Operating Loss Carryforwards, Total	264,400
Domestic Tax Authority [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	6,500
Domestic Tax Authority [Member] \| Before Tax Year 2018 [Member]
Operating Loss Carryforwards, Total	114,900
Domestic Tax Authority [Member] \| Tax Years 2018 to 2020 [Member]
Operating Loss Carryforwards, Total	149,500
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	141,500
State and Local Jurisdiction [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	$ 4,000

Note 16 - Income Taxes - Net Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2020	Dec. 31, 2019
Accruals and other	$ 4,136	$ 3,672
Research credits	7,275	7,275
Net operating loss carryforward	65,274	52,361
Section 59(e) R&D expenditures	7,473	8,933
Deferred revenue	20,848	21,324
Total deferred tax assets	105,006	93,565
Valuation allowance	(105,006)	(93,565)
Net deferred tax assets	$ 0	$ 0

Note 16 - Income Taxes - Reconciliation of Statutory Federal Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Tax at statutory federal rate	$ (8,486)	$ (11,180)	$ (9,901)
State tax—net of federal benefit	(3,587)	(2,538)	(792)
General business credits	0	0	(500)
Stock options	636	800	1,048
Other	0	7	295
Change in valuation allowance	11,441	12,914	9,852
Provision for income taxes	$ 4	$ 3	$ 2