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Document And Entity Information - USD ($)	12 Months Ended
Document And Entity Information - USD ($)	Dec. 31, 2019	Mar. 05, 2020	Jun. 28, 2019
Document Information [Line Items]
Entity Registrant Name	ACELRX PHARMACEUTICALS INC
Entity Central Index Key	0001427925
Trading Symbol	acrx
Current Fiscal Year End Date	--12-31
Entity Filer Category	Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	No
Entity Emerging Growth Company	false
Entity Small Business	true
Entity Interactive Data Current	Yes
Entity Common Stock, Shares Outstanding (in shares)		80,411,856
Entity Public Float			$ 197,006,167
Entity Shell Company	false
Document Type	10-K
Document Period End Date	Dec. 31, 2019
Document Fiscal Year Focus	2019
Document Fiscal Period Focus	FY
Amendment Flag	false
Title of 12(b) Security	Common Stock, $0.001 par value

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Current Assets:
Cash and cash equivalents	$ 14,684	$ 87,975
Short-term investments	51,453	17,740
Accounts receivable, net	432	49
Tax receivable	88	352
Inventories, net	3,295	854
Prepaid expenses and other current assets	1,736	1,024
Total current assets	71,688	107,994
Operating lease right-of-use assets	3,928
Property and equipment, net	14,552	11,483
Long-term tax receivable	263	351
Other assets	925	705
Total Assets	91,356	120,533
Current Liabilities:
Accounts payable	1,720	2,070
Accrued liabilities	5,528	4,540
Long-term debt, current portion	4,630	8,611
Deferred revenue, current portion	411	315
Operating lease liabilities, current portion	970
Liability related to the sale of future royalties, current portion	352	392
Total current liabilities	13,611	15,928
Long-term debt, net of current portion	20,517	3,380
Deferred revenue, net of current portion	2,833	3,148
Operating lease liabilities, net of current portion	3,640
Liability related to the sale of future royalties, net of current portion	91,683	93,287
Other long-term liabilities	490	537
Total liabilities	132,774	116,280
Commitments and Contingencies
Stockholders’ (Deficit) Equity:
Common stock, $0.001 par value—200,000,000 shares authorized as of December 31, 2019 and 100,000,000 shares authorized as of December 31, 2018; 79,573,101 and 78,757,930 shares issued and outstanding as of December 31, 2019 and December 31, 2018, respectively	79	78
Additional paid-in capital	356,609	349,194
Accumulated deficit	(398,106)	(345,019)
Total stockholders’ (deficit) equity	(41,418)	4,253
Total Liabilities and Stockholders’ (Deficit) Equity	$ 91,356	$ 120,533

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2019	Dec. 31, 2018
Common stock, par value (in dollars per share)	$ 0.001	$ 0.001
Common stock, authorized (in shares)	200,000,000	100,000,000
Common stock, issued (in shares)	79,573,101	78,757,930
Common stock, outstanding (in shares)	79,573,101	78,757,930

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue:
Revenue	$ 2,289	$ 2,151	$ 7,995
Operating costs and expenses:
Cost of goods sold	6,806	3,976	10,659
Research and development	4,661	13,137	19,409
Selling, general and administrative	45,027	20,765	16,609
Total operating costs and expenses	56,494	37,878	46,677
Loss from operations	(54,205)	(35,727)	(38,682)
Other income (expense):
Interest expense	(2,535)	(2,217)	(3,316)
Interest income and other income (expense), net	2,166	1,138	510
Non-cash interest income (expense) on liability related to sale of future royalties	1,337	(10,341)	(10,721)
Total other income (expense)	968	(11,420)	(13,527)
Net loss before income taxes	(53,237)	(47,147)	(52,209)
Provision (benefit) for income taxes	3	2	(701)
Net loss	(53,240)	(47,149)	(51,508)
Other comprehensive loss:
Unrealized losses on available for sale securities			(3)
Comprehensive loss	$ (53,240)	$ (47,149)	$ (51,511)
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (0.67)	$ (0.81)	$ (1.10)
Shares used in computing net loss per share of common stock, basic and diluted –see Note 13 (in shares)	79,184,266	58,408,548	46,883,535
Product [Member]
Revenue:
Revenue	$ 1,830	$ 825	$ 6,673
Contract and Other Collaboration [Member]
Revenue:
Revenue	$ 459	$ 1,326	$ 1,322

Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Dec. 31, 2016	45,333,790
Balance at Dec. 31, 2016	$ 45	$ 240,977	$ (246,362)	$ 3	$ (5,337)
Stock-based compensation		4,294			4,294
Net proceeds from issuance of common stock in connection with equity financings (in shares)	5,401,099
Net proceeds from issuance of common stock in connection with equity financings	$ 6	15,688			15,694
Issuance of common stock upon exercise of stock options (in shares)	69,372
Issuance of common stock upon exercise of stock options		105			105
Issuance of common stock upon ESPP purchase (in shares)	94,893
Issuance of common stock upon ESPP purchase		246			246
Change in unrealized gains and losses on investments				(3)	(3)
Net loss			(51,508)		(51,508)
Balance (in shares) at Dec. 31, 2017	50,899,154
Balance at Dec. 31, 2017	$ 51	261,310	(297,870)		(36,509)
Stock-based compensation		5,168			5,168
Net proceeds from issuance of common stock in connection with equity financings (in shares)	27,364,301
Net proceeds from issuance of common stock in connection with equity financings	$ 27	81,498			81,525
Issuance of common stock upon exercise of stock options (in shares)	135,385
Issuance of common stock upon exercise of stock options		401			401
Issuance of common stock upon ESPP purchase (in shares)	182,360
Issuance of common stock upon ESPP purchase		275			275
Change in unrealized gains and losses on investments
Net loss			(47,149)		(47,149)
Issuance of common stock upon exercise of warrants (in shares)	176,730
Issuance of common stock upon exercise of warrants		542			542
Balance (in shares) at Dec. 31, 2018	78,757,930
Balance at Dec. 31, 2018	$ 78	349,194	(345,019)		4,253
Cumulative effect adjustment for adoption of ASU No. 2016-02 \| Accounting Standards Update 2016-02 [Member]			153		153
Stock-based compensation		5,057			5,057
Net proceeds from issuance of common stock in connection with equity financings (in shares)	500,000
Net proceeds from issuance of common stock in connection with equity financings		1,233			$ 1,233
Issuance of common stock upon exercise of stock options (in shares)	111,702				111,702
Issuance of common stock upon exercise of stock options		270			$ 270
Issuance of common stock upon ESPP purchase (in shares)	203,469
Issuance of common stock upon ESPP purchase	$ 1	472			473
Change in unrealized gains and losses on investments
Net loss			(53,240)		(53,240)
Issuance of warrants related to debt financing		383			383
Balance (in shares) at Dec. 31, 2019	79,573,101
Balance at Dec. 31, 2019	$ 79	$ 356,609	$ (398,106)		$ (41,418)

Condensed Consolidated Statements of Cash Flows - USD ($)	3 Months Ended				12 Months Ended			51 Months Ended
	Dec. 31, 2019	Mar. 31, 2019	Dec. 31, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (14,423,000)	$ (13,674,000)	$ (12,558,000)	$ (11,592,000)	$ (53,240,000)	$ (47,149,000)	$ (51,508,000)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash royalty revenue related to royalty monetization					(312,000)	(289,000)	(151,000)
Non-cash interest (income) expense on liability related to royalty monetization					(1,337,000)	10,341,000	10,721,000	$ 31,535,000
Depreciation and amortization					1,668,000	575,000	1,744,000
Non-cash interest expense related to debt financing					712,000	613,000	1,265,000
Stock-based compensation					5,057,000	5,168,000	4,294,000
Inventory impairment charge					951,000		369,000
Other					(773,000)	(201,000)	(198,000)
Changes in operating assets and liabilities:
Accounts receivable					(383,000)	1,484,000	4,300,000
Inventories					(3,392,000)	102,000	920,000
Prepaid expenses and other assets					(465,000)	(850,000)	175,000
Tax receivable					352,000		(703,000)
Other assets					(220,000)
Accounts payable					(19,000)	458,000	309,000
Accrued liabilities					1,141,000	922,000	(1,301,000)
Operating lease liabilities					(701,000)
Deferred revenue					(219,000)	(362,000)	(361,000)
Deferred rent						113,000	360,000
Net cash used in operating activities					(51,180,000)	(29,075,000)	(29,765,000)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment					(3,470,000)	(819,000)	(2,405,000)
Purchase of investments					(100,068,000)	(30,558,000)	(7,565,000)
Proceeds from maturities of investments					66,975,000	20,500,000
Net cash used in investing activities					(36,563,000)	(10,877,000)	(9,970,000)
CASH FLOWS FROM FINANCING ACTIVITIES:
Proceeds from issuance of long-term debt					25,000,000
Payment of costs in connection with refinancing of long-term debt					(190,000)		(204,000)
Payment of long-term debt					(3,470,000)	(7,718,000)	(3,514,000)
Extinguishment of debt					(8,864,000)
Net proceeds from issuance of common stock in connection with equity financings					1,233,000	81,525,000	15,694,000
Net proceeds from issuance of common stock through equity plans					743,000	1,218,000	351,000
Net cash provided by financing activities					14,452,000	75,025,000	12,327,000
NET (DECREASE) INCREASE IN CASH, CASH EQUIVALENTS					(73,291,000)	35,073,000	(27,408,000)
CASH, CASH EQUIVALENTS —Beginning of period		$ 87,975,000		$ 52,902,000	87,975,000	52,902,000	80,310,000
CASH, CASH EQUIVALENTS —End of period	$ 14,684,000		$ 87,975,000		14,684,000	87,975,000	52,902,000	$ 14,684,000
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest					1,712,000	1,667,000	2,043,000
Income taxes (refunded) paid					(350,000)	2,000	2,000
NONCASH INVESTING AND FINANCING ACTIVITIES:
Purchases of property and equipment in accounts payable						410,000	222,000
Leasehold paid with note payable					899,000
Transfer of tenant improvement allowance to sublease					242,000
Establishment of right-of-use asset due to the adoption of ASU 2016-02					$ 4,730,000

Note 1 - Organization and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Basis of Presentation and Significant Accounting Policies [Text Block]

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 in Europe) and Zalviso

, are

both 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. 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. The commercial launch of DSUVIA in the United States occurred in the

first

quarter of

2019.

In geographies where AcelRx decides

not

to commercialize products by itself, including for DZUVEO in Europe, 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 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 is currently being commercialized by Grünenthal GmbH, or Grünenthal.

DSUVIA/DZUVEO

DSUVIA, known as DZUVEO in Europe, approved by the FDA in

November 2018

and approved 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.

Zalviso

Zalviso delivers

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

trials already completed in the Zalviso NDA resubmission.

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 grants Grünenthal rights to commercialize the Zalviso PCA system, or the Product, in the

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 approved 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 will exclusively manufacture and supply 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 Amended Agreements.

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 with Grünenthal to PDL BioPharma, Inc., or PDL, in a transaction referred to as the Royalty Monetization. The FDA approved DSUVIA in

November 2018

and the Company began its commercial launch of DSUVIA in the

first

quarter of

2019.

As a result, 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.

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 amount reported in the Consolidated Balance Sheets as restricted cash has been reclassified to other assets at

December 31, 2018,

the amounts reported in the Consolidated Balance Sheets as deferred rent and contingent put option liability have been reclassified to other long-term liabilities at

December 31, 2018,

and Zalviso product sales revenue has been reclassified to product sales from contract and other collaboration in the Consolidated Statements of Comprehensive Loss.

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

“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

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 net product sales revenue relates to sales in the United States. The Company’s collaboration revenue relates to the Amended License Agreement with Grünenthal to commercialize Zalviso in the countries of the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia. The Company’s contract and other revenue relates to the U.S. Department of Defense funding that supported the development of DSUVIA in the United States.

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 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 and Zalviso drug cartridge and device components, including the controller, the dispenser kit and the accessories.

DSUVIA is available in the U.S. for distribution primarily through a limited number of wholesalers and is

not

available in retail pharmacies. Zalviso is sold in Europe by the Company’s collaboration partner, Grünenthal. Revenue and accounts receivable are concentrated with these customers.

Accounts Receivable,

The Company has receivables from its distributors and collaboration partner, Grünenthal. To date, the Company has

not

had a bad debt allowance because of the limited number of financially sound customers who have historically paid their balances timely. 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, 2019

is collectible.

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. Because the predetermined, contractual transfer prices the Company is receiving from Grünenthal are less than the direct costs of manufacturing, all Zalviso inventories are carried at net realizable value.

Property and Equipment

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

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 other expense 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

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

“Long-Term Debt”.

Leases

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 balance sheet as right-of-use assets, operating lease liabilities current and operating lease liabilities non-current. As a result, the Company

longer recognizes deferred rent on the balance sheet.

Revenue from Contracts with Customers

Beginning

January

2018,

the Company has followed 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

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. Revenue from product sales is recorded at the transaction price, net of estimates for variable consideration consisting of distributor fees, GPO discounts, GPO administrative fees and 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:

●

Distributor Fees – The Company offers contractually determined fees to its distributors.

●

GPO Discounts - The Company offers discounts to GPO members. These discounts are taken when the GPO members purchase DSUVIA from the Company’s distributors, who then charge the discount amount back to the Company.

●

GPO Administrative 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.

●

Returns – The Company allows its distributors to return product for credit up to

months after its 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.

●

Prompt Pay Discounts – The Company offers cash discounts to its distributors, generally

of the sales price, as an incentive for prompt payment. The Company accounts for cash discounts by reducing accounts receivable by the prompt pay discount amount and recognizes the discount as a reduction of revenue in the same period the related revenue is recognized.

The Company believes its estimated allowance for product returns requires a high degree of judgment and is subject to change based on its limited experience and certain quantitative and qualitative factors. The Company believes its estimated allowances for distributor fees, GPO discounts and GPO administrative fees and prompt pay discounts do

not

require a high degree of judgment because the amounts are settled within a relatively short period of time.

Amounts accrued for product revenue allowances and related accruals are evaluated each reporting period and adjusted when trends or significant events indicate that a change in estimate is appropriate and to reflect actual experience. Product revenue-related liabilities are recorded in the Company’s Consolidated Balance Sheets as accrued liabilities, while prompt pay discounts are recorded in the Company’s Consolidated Balance Sheets as a reduction in accounts receivable. 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 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.

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.

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 Amended Agreements with Grünenthal, the Company sells Zalviso to Grünenthal at predetermined, contractual transfer prices that are less than the direct costs of manufacturing and recognizes indirect costs as period costs where they are 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

$1.1

million,

$0.5

million and

$0.0

million for the years ended

December 31, 2019,

2018

and

2017,

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 Company uses its historical option exercise experience and the volatility of its common stock as the basis for its assumptions regarding expected term and volatility. The risk-free rate is based on the U.S. Treasury yield curve in effect at the time of grant commensurate with the expected life assumption. Effective

January 1, 2017,

the Company adopted ASU

2016

and elected to recognize forfeitures when they occur using a modified retrospective approach, which did

not

have a material impact on its Consolidated Financial Statements.

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

September 2015,

the Company sold certain royalty and milestone payment rights from the sales of Zalviso in the European Union by its commercial partner, Grünenthal, pursuant to the License Agreement, as then amended, to PDL for gross proceeds of

$65.0

million. The Company continues to have significant continuing involvement in the Royalty Monetization primarily due to an obligation to supply Zalviso to Grünenthal. 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 Grünenthal’s sales and promotion of Zalviso, 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 more 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 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

“Net Loss per Share of Common Stock”.

Recently Adopted Accounting Pronouncement

August 29, 2018,

the Financial Accounting Standards Board, or FASB, issued ASU

No.

2018

15,

“

Intangibles – Goodwill and Other – Internal Use Software (Subtopic

350

)”

. The FASB’s new guidance aligns the requirements for capitalizing implementation costs in a Cloud Computing Arrangement, or CCA, service contract with the requirements for capitalizing implementation costs incurred for an internal-use software license.

The amendments in ASU

No.

2018

require the entity to present the expense related to the capitalized implementation costs in the same line item in the statement of income as the fees associated with the hosting element (service) of the arrangement and classify payments for capitalized implementation costs in the statement of cash flows in the same manner as payments made for fees associated with the hosting element. The entity is also required to present the capitalized implementation costs in the statement of financial position in the same line item that a prepayment for the fees of the associated hosting arrangement would be presented.

ASU

No.

2018

is effective for public business entities for fiscal years beginning after

December 15, 2019,

and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period for which financial statements have

not

been issued. Entities can choose to adopt the new guidance (

) prospectively to eligible costs incurred on or after the date this guidance is

first

applied or (

) retrospectively. The Company early adopted ASU

No.

2018

effective

January 1, 2019

under the prospective method, which did

not

have a material effect on the Company’s results of operations, financial condition or cash flows.

August 2018,

the U.S. Securities and Exchange Commission, or SEC, published Release

No.

10532,

Disclosure Update and Simplification,

or DUSTR, which adopted amendments to certain disclosure requirements that have become redundant, duplicative, overlapping, outdated or superseded, in light of other SEC disclosure requirements, U.S. Generally Accepted Accounting Principles, or GAAP, or changes in the information environment. While most of the DUSTR amendments eliminate outdated or duplicative disclosure requirements, the final rule amends the interim financial statement requirements to include a reconciliation of changes in stockholders’ (deficit) equity in the notes or as a separate statement for each period for which a statement of comprehensive loss is required to be filed. The new interim reconciliation of changes in stockholders’ (deficit) equity has been included in the Company's interim financial statements effective

January 1, 2019.

February 2016,

the FASB issued ASU

No.

2016

02,

Leases (Topic

842

)

, which establishes a new lease accounting model for lessees. In

January,

July

and

December 2018,

the FASB issued additional amendments to the new lease guidance relating to, transition, and clarification. The

July 2018

amendment, ASU

No.

2018

11,

Leases (Topic

842

): Targeted Improvements

, provided an optional transition method that allows entities to elect to apply the standard prospectively at its effective date, versus recasting the prior periods presented. The new standard establishes a right-of-use, or ROU, model that requires a lessee to record an ROU asset and a lease liability on the balance sheet for all leases with terms longer than

months. Disclosure requirements have been enhanced with the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. ASU

No.

2016

became effective for the Company on

January 1, 2019.

The Company has implemented the standard using an optional transition method that allows the Company to initially apply the new leases standard as of the adoption date and recognize a cumulative-effect adjustment to the opening balance of accumulated deficit in the period of adoption. In connection with the adoption, the Company has elected to utilize the package of practical expedients, including: (

)

not

reassess the lease classification for any expired or existing leases, (

)

not

reassess the treatment of initial direct costs as they related to existing leases, and (

)

not

reassess whether expired or existing contracts are or contain leases. In addition, the Company elected the hindsight practical expedient to determine the lease term for existing leases. The election of the hindsight practical expedient resulted in the extension of the lease term for the Company’s embedded lease.

The adoption of the new leases standard resulted in the following adjustments to the Consolidated Balance Sheets as of

January 1, 2019 (

in thousands):

	Increase/(Decrease)
Operating lease right-of-use assets	$	4,730
Accrued liabilities (a)	$	(100	)
Operating lease liabilities	$	484
Operating lease liabilities, net of current portion	$	4,610
Deferred rent, net of current portion	$	(416	)
Accumulated deficit (b)	$	(153	)

	(a)	Represents current portion of Deferred rent reclassified to Operating lease liabilities.

	(b)	Represents cumulative-effect adjustment upon adoption of ASU No. 2016 - 02.

The adoption of ASU

No.

2016

02,

the new leases standard, did

not

impact previously reported financial results because the impact to prior periods was reflected as a cumulative-effect adjustment to the accumulated deficit under the optional transition method.

Recently Issued Accounting Pronouncements

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

replaces the incurred loss impairment methodology in current GAAP with a methodology that reflects expected credit losses and requires consideration of a broader range of reasonable and supportable information to inform credit loss estimates. ASU

2016

is effective for the Company beginning

January 1, 2023,

with early adoption allowed beginning

January 1, 2020.

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

and ASU

2019

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 and cash flows.

Note 2 - Investments and Fair Value Measurement

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Investments and Fair Value Measurement Disclosure [Text Block]

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, 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

	As of December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	2,037	$	—	$	—	$	2,037
Money market funds		1,436		—		—		1,436
U.S. government agency securities		10,181		—		—		10,181
Commercial paper		74,321		—		—		74,321
Total cash and cash equivalents		87,975		—		—		87,975

Short-term investments:
U.S. government agency securities		1,497		—		—		1,497
Commercial paper		16,243		—		—		16,243
Total short-term investments		17,740		—		—		17,740
Total cash, cash equivalents and short-term investments	$	105,715	$	—	$	—	$	105,715

None

of the available-for-sale securities held by the Company had material unrealized losses and there were

realized losses for the years ended

December

31,

2019

and

2018.

There were

other-than-temporary impairments for these securities as of

December

31,

2019

2018.

gross realized gains or losses were recognized on the available-for-sale securities and, accordingly, there were

amounts reclassified out of accumulated other comprehensive income to earnings during the years ended

December 31, 2019

and

2018.

As of

December

31,

2019

and

2018,

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

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, 2019,

the Company held, in addition to Level II assets, a contingent put option liability associated with the Loan Agreement with Oxford. Similarly, as of

December 31, 2018,

the Company held a contingent put option liability associated with the Amended and Restated Loan and Security Agreement, or the Amended Loan Agreement, or Prior Agreement, with Hercules Capital Funding Trust

2014

and Hercules Technology II, L.P., together, Hercules. See Note

“Long-Term Debt” for further description. The Company’s estimate of fair value of each of the contingent put option liabilities 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 these liabilities are 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, 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

	As of December 31, 2018
	Fair Value		Level I		Level II		Level III
Assets
Money market funds	$	1,436	$	1,436	$	—	$	—
U.S. government agency securities		11,678		—		11,678		—
Commercial paper		90,564		—		90,564		—
Total assets measured at fair value	$	103,678	$	1,436	$	102,242	$	—
Liabilities
Contingent put option liability	$	121	$	—	$	—	$	121
Total liabilities measured at fair value	$	121	$	—	$	—	$	121

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,

2019

and

2018

(in thousands):

	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

	Year Ended December 31, 2018
Fair value—beginning of period	$	207
Change in fair value of contingent put option associated with Amended Loan Agreement		(86	)
Fair value—end of period	$	121

Note 3 - Inventories

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Inventory Disclosure [Text Block]

Inventories

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,
	2019		2018
Raw materials	$	1,153	$	694
Work-in-process		593		160
Finished goods		1,549		—
Inventories	$	3,295	$	854

During the year ended

December 31, 2019,

the Company recorded a write-down of inventory of approximately

$1.0

million as a result of an analysis to estimate potential DSUVIA inventory that

may

expire before being sold. This represents initial DSUVIA batches produced for development and therefore represented shorter dated product than batches manufactured for commercial sale. During the year ended

December 31, 2017,

the Company recorded an inventory impairment charge of

$0.4

million, primarily for Zalviso raw materials inventory on hand, plus related purchase commitments. 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

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Property, Plant and Equipment Disclosure [Text Block]

Property and Equipment

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

	As of December 31,
	2019			2018
Laboratory equipment	$	4,389		$	3,972
Leasehold improvements		4,616			4,469
Computer equipment and software		1,749			237
Construction in process		11,949			10,593
Tooling		1,109			1,109
Furniture and fixtures		292			47

		24,104			20,427
Less accumulated depreciation and amortization		(9,552	)		(8,944	)
Property and equipment, net	$	14,552		$	11,483

Depreciation and amortization expense was

$0.9

million,

$0.5

million and

$1.7

million during the years ended

December

31,

2019,

2018

and

2017,

respectively.

Note 5 - Revenue from Contracts with Customers

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Revenue from Contract with Customer [Text Block]

Revenue from Contracts with Customers

The following table summarizes revenue from contracts with customers for the years ended

December 31, 2019,

2018

and

2017

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,
	201 9		201 8		201 7
Product sales:
DSUVIA	$	377	$	—	$	—
Zalviso		1,453		825		6,673
Total product sales		1,830		825		6,673
Contract and other collaboration:
DoD Contract revenue		—		838		852
Non-cash royalty revenue related to Royalty Monetization (See Note 8)		312		289		151
Royalty revenue		104		96		50
Other revenue		43		103		269
Total revenues from contract and other collaboration		459		1,326		1,322
Total revenue	$	2,289	$	2,151	$	7,995

For additional detail on the Company’s accounting policy regarding revenue recognition, refer to Note

“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 is sold in Europe by the Company’s collaboration partner, Grünenthal.

Contract and Other Collaboration

Amended License Agreement

Under the Amended License Agreement with Grünenthal, the Company is 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). Grünenthal will also make tiered royalty and supply and trademark fee payments in the mid-teens up to the mid-twenties percent range, depending on the level of sales achieved, on net sales of Zalviso. A portion of the tiered royalty payment, exclusive of the supply and trademark fee payments, will be paid to PDL in connection with the Royalty Monetization. For additional information on the Royalty Monetization with PDL, see Note

“Liability Related to Sale of Future Royalties”. Unless earlier terminated, the Amended License Agreement continues in effect until the expiration of the obligation of Grünenthal to make royalty and supply and trademark fee payments, which supply and trademark fee continues for so long as the Company continues to supply the Product to Grünenthal. The Amended License Agreement is subject to earlier termination in the event the parties mutually agree, by a party in the event of an uncured material breach by the other party, upon the bankruptcy or insolvency of either party, or by Grünenthal for convenience.

Amended MSA

Under the terms of the Amended MSA with Grünenthal, the Company will manufacture and supply the Product for use in the Field for the Territory exclusively for Grünenthal. The Product will be supplied at prices approximating the Company’s manufacturing cost, subject to certain caps, as defined in the MSA Amendment. The MSA Amendment requires the Company to use commercially reasonable efforts to enter stand-by contracts with

third

parties providing significant supply and manufacturing services and, under certain specified conditions, permits Grünenthal to use a

third

-party back-up manufacturer to manufacture the Product for Grünenthal’s commercial sale in the Territory.

The Amended Agreements entitle the Company to receive additional payments upon the achievement of certain development milestones which relate to post approval product enhancements, expanded market opportunities and manufacturing efficiencies for Zalviso and require future research, development and regulatory activities. These payments are excluded from the transaction price as they are considered payments for optional additional services that Grünenthal

may

elect in the future. When these services are elected, they will be considered as a new contract under ASC Topic

606

and will

not

impact the revenue recognition of the performance obligations identified under Amended Agreements.

The Amended Agreements also include milestone payments related to specified net sales targets, totaling

$166.0

million. These payments are considered sales-based license royalties under ASC Topic

606

and will be recognized apart from the other contract consideration when the related sales occur.

The Company recognizes revenue from license rights when the customer can use and benefit from the license rights. The Company recognizes revenue from its services performance obligations over time using a cost-to-cost input method which best represents the incremental benefit that the customer receives as control is transferred.

DoD Contract

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

The Company has entered into the Amended Agreements with Grünenthal related to Zalviso. 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. This deferred revenue is being recognized on a straight-line basis over the period such discount is made available to Grünenthal, which is estimated to continue through

2029.

The following table presents changes in the Company’s contract liability for the year ended

December 31, 2019:

	Balance at Beginning of the Period		Additions		Deductions			Balance at the end of the Period
	(in thousands)
Contract liability:
Deferred revenue – Amended Agreements	$	3,463	$	—	$	(315	)	$	3,148
Deferred revenue – Other		—		96		—			96
Deferred revenue	$	3,463	$	96	$	(315	)	$	3,244

For the years ended

December

31,

2019

and

2018,

the Company recognized the following revenue from performance obligations satisfied (in thousands):

	Year ended December 31, 2019		Year ended December 31, 2018
Amounts included in contract liabilities at the beginning of the period:
Performance obligations satisfied – Amended Agreements	$	315	$	362
New activities in the period from performance obligations satisfied:
Performance obligations satisfied – Amended Agreements		1,181		566
Total revenue from performance obligations satisfied	$	1,496	$	928

Note 6 - Long-term Debt

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Long-term Debt [Text Block]

Long-Term Debt

Prior Agreement with Hercules

December

16,

2013,

AcelRx entered into an Amended and Restated Loan and Security Agreement, or the Original Loan Agreement. with Hercules Technology II, L.P. and Hercules Capital, Inc., formerly known as Hercules Technology Growth Capital, Inc., together, the Lenders. In connection with the Original Loan Agreement, the Company issued a warrant to each Lender which, collectively, were exercisable for an aggregate of

176,730

shares of common stock and each carried an exercise price of

$6.79

per share. See Note

“Warrants” for further description.

March 2, 2017,

the Company entered into the Amended Loan Agreement, which amended and restated the Original Loan Agreement. Pursuant to the Amended Loan Agreement, the Company borrowed the

first

tranche of approximately

$20.5

million upon closing of the transaction on

March 2, 2017,

which was represented by secured term promissory notes, or the Notes. The Company used all of the proceeds from the

first

tranche to repay its obligations under the Original Loan Agreement, including a final payment of

$1.7

million made on

October 1, 2017.

The interest rate was calculated at a rate equal to the greater of either (i)

9.55%

plus the prime rate as reported from time to time in The Wall Street Journal minus

3.50%,

and (ii)

9.55%.

Payments under the Prior Agreement were interest-only until

October 1, 2017

followed by equal monthly payments of principal and interest through the scheduled maturity date of

March 1, 2020.

In addition, the Prior Agreement required a final payment equal to

6.5%

of the aggregate principal amount of

$20.5

million in loans, or the End of Term Fee, owed upon full repayment of the loan. 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.

The Company’s obligations under the Prior Agreement were secured by a security interest in substantially all of its assets, other than its intellectual property. In addition, upon an event of default, including a change of control, Hercules had the option to accelerate repayment of the Amended Loan Agreement, including payment of any applicable prepayment charges. This option was considered a contingent put option liability, as the holder of the loan has the ability to exercise the option in the event of default, and is considered an embedded derivative, which must be valued and separately accounted for in the Company’s consolidated financial statements. As of

December 31, 2018,

the estimated fair value of the contingent put option liability was

$0.1

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

“Investments and Fair Value Measurement” for further description.

The accrued balance due under the Prior Agreement was

$12.0

million at

December 31, 2018.

Interest expense related to the Prior Agreement was

$0.6

million,

$2.2

million and

$3.3

million for the years ended

December 31, 2019,

2018

and

2017,

respectively.

Loan Agreement with Oxford

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. 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

-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%.

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

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

if the prepayment occurs before

May 30, 2020,

1.5%

if the prepayment occurs after

May 30, 2020,

but on or before

May 30, 2021

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

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, 2019,

the estimated fair value of the contingent put option liability was

$0.4

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

“Investments and Fair Value Measurement” for further description.

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 have been classified within stockholders’ (deficit) equity and accounted for as a discount to the loan by allocating the gross proceeds on a relative fair value basis. For further discussion, see Note

“Warrants”.

The accrued balance due under the Loan Agreement was

$24.2

million at

December 31, 2019.

Interest expense related to the Loan Agreement was

$1.9

million,

$0.6

million of which represented amortization of the debt discount, for the year ended

December 31, 2019.

Non-

nterest

earing

ayments

for the

onstruction of

easehold

mprovements

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.

The total obligation under the SRA is

$2.0

million of which

$1.5

million has been incurred as of

December 31, 2019.

The effective interest rate related to the payments at

December 31, 2019

was

13.61%.

The following table summarizes the balance of the future payments at

December 31, 2019 (

in thousands):

	As of December 31,
	2019
Present value of the face amount of $1.0 million	$	899
Less: current portion		463
Long-term debt, net of current portion	$	436

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,

2019

(in thousands):

2020	$	6,936
2021		10,429
2022		9,187
2023		5,530
Total payments		32,082
Less amount representing interest		(4,792	)
Notes payable, gross		27,290
Less: Unamortized portion of EOT Fee		(978	)
Less: Unamortized discount on notes payable		(1,165	)
Long-term debt		25,147
Less current portion		(4,630	)
Long-term debt, net of current portion	$	20,517

Note 7 - Leases

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Lessee, Operating Leases [Text Block]

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

commencing on

February 1

. 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.

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

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

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

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

December 31, 2021.

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

	Year Ended December 31, 2019
Operating lease costs	$	1,360
Sublease income		(596	)
Net lease costs	$	764

Other information related to the operating leases is presented in the following table (in thousands, except years and percentages):

	Year Ended December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases	$	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, 2019
Weighted-average remaining term – operating lease (in years)		4.08
Weighted-average discount rate – operating lease		11.72	%

Maturities of lease liabilities as of

December 31, 2019

are presented in the following table (in thousands):

Year:
2020	$	1,268
2021		1,305
2022		1,345
2023		1,386
2024		116
Total future minimum lease payments		5,420
Less imputed interest		(810	)
Total	$	4,610

Reported as:

Operating lease liabilities	$	970
Operating lease liabilities, net of current portion		3,640
Total lease liability	$	4,610

Future minimum sublease payments as of

December 31, 2019

are presented in the following table (in thousands):

Year:
2020	$	593
2021		610
2022		629
2023		648
2024		54
Total future minimum sublease payments	$	2,534

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

Reported as:

Prepaid expenses and other current assets	$	78
Other assets		354
Total rent receivable	$	432

Note 8 - Liability Related to Sale of Future Royalties

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Liability Related to Sale of Future Royalties

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 will 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%

$44.5

million), subject to the capped amount. The Company is 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 EC approval of the MAA for Zalviso.

The Company and ARPI LLC continue to retain certain duties and obligations under the Amended License Agreement. These include the collection of the royalty and milestones amounts due and enforcement of related provisions under the Amended License Agreement, among others. In addition, the Company must prepare a quarterly distribution report relating to the Amended License Agreement, containing among other items, the amount of royalty and milestone payments received, reimbursable expenses and set-offs. The Company and ARPI LLC must also provide PDL with notice of certain communications, events or actions with respect to the Amended License Agreement and infringement of any underlying intellectual property.

The Company has significant continuing involvement in the Royalty Monetization primarily due to an obligation to act as the intermediary for the supply of Zalviso to Grünenthal. Under the relevant accounting guidance, because of its 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 prior estimates or the timing of such payments is materially different than its prior estimates, the Company prospectively adjusts 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. The Company currently estimates that future payments to PDL over the remaining life of the arrangement will be approximately

$20

million, therefore, a contingent gain of approximately

$45

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 arrangement, there are significant uncertainties surrounding the amount and timing of 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

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 year ended

December 31, 2019

was approximately

1.4%.

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 years ended

December 31, 2018

and

December 31, 2017

was approximately

11.6%

and

13.6%,

respectively.

The following table shows the activity within the liability account during the year ended

December 31, 2019 (

in thousands):

	Year ended December 31, 201 9			Period from inception to December 31, 201 9
Liability related to sale of future royalties — beginning balance	$	93,679		$	—
Proceeds from sale of future royalties		—			61,184
Non-cash royalty revenue		(307	)		(684	)
Non-cash interest (income) expense recognized		(1,337	)		31,535
Liability related to sale of future royalties as of December 31, 2019		92,035			92,035
Less: current portion		(352	)		(352	)
Liability related to sale of future royalties — net of current portion	$	91,683		$	91,683

As royalties are remitted to PDL from ARPI LLC, as described in Note

“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.

Note 9 - Warrants	12 Months Ended
Note 9 - Warrants	Dec. 31, 2019
Notes to Financial Statements
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, 2019, 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. Original Loan Agreement Warrants In connection with the Original Loan Agreement, the Company issued warrants to the Lenders which were exercisable for an aggregate of 176,730 shares of common stock with an exercise price of $6.79 per share, or the Warrants. In connection with Amendment No. 2 to the Original Loan Agreement, the Company reduced the exercise price of the warrants already held by the Lenders from the previous exercise price of $6.79 per share to $3.88 per share, or the First Warrant Amendments. In connection with Amendment No. 3 to the Original Loan Agreement, the Company reduced the exercise price of the warrants already held by the Lenders from the previous exercise price of $3.88 per share to $3.07 per share, or the Second Warrant Amendments. In December 2018, all of the outstanding warrants were exercised to purchase 176,730 shares of common stock which were issued to the Lenders. 2012 Private Placement Warrants In connection with the Private Placement, completed in June 2012, the Company issued PIPE warrants to purchase up to 2,630,103 shares of common stock. The per share exercise price of the PIPE warrants was $3.40 which equals the closing consolidated bid price of the Company’s common stock on May 29, 2012, the effective date of the Purchase Agreement. The PIPE warrants issued in the Private Placement became exercisable six months after the issuance date and expire on the five -year anniversary of the initial exercisability date. Under the terms of the PIPE warrants, upon certain transactions, including a merger, tender offer, sale of all or substantially all of the assets of the Company or if a person or group shall become the owner of 50% of the Company’s issued and outstanding common stock, which is outside of the Company’s control, each PIPE warrant holder may elect to receive a cash payment in exchange for the warrant, in an amount determined by application of the Black-Scholes option-pricing model. Accordingly, the PIPE warrants were recorded as a liability at fair value and then marked to fair value each reporting period, with changes in estimated fair value recorded through the Consolidated Statements of Comprehensive Loss in interest income and other income (expense), net. The PIPE warrants were valued using the Black-Scholes option-pricing model, the inputs for which included exercise price of the PIPE warrants, market price of the underlying common shares, expected term, volatility based on a group of the Company’s peers and the risk-free rate corresponding to the expected term of the PIPE warrants. Upon execution of the Purchase Agreement, the fair value of the PIPE warrants was estimated to be $5.8 million, which was recorded as a liability. The change in fair value for the year ended December 31, 2017, which was recorded as other income, was $0.3 million. During the year ended December 31, 2017, 512,456 warrants expired unexercised and there are no remaining PIPE warrants outstanding.

Note 10 - Commitments and Contingencies	12 Months Ended
Note 10 - Commitments and Contingencies	Dec. 31, 2019
Notes to Financial Statements
Commitments and Contingencies Disclosure [Text Block]	1 0 . 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
Note 11 - Stockholders' Equity	Dec. 31, 2019
Notes to Financial Statements
Stockholders' Equity Note Disclosure [Text Block]	1 1 . Stockholders’ Equity Common Stock 2018 Underwritten Public Offerings On November 14, 2018, the Company completed an underwritten public offering of 14,603,173 shares of common stock, at a price of $3.15 per share to the public. The total gross proceeds from this offering were approximately $46.0 million with net proceeds to the Company of $43.1 million after deducting the underwriting discounts and commissions and other offering expenses payable by us. On July 16, 2018, the Company completed an underwritten public offering of 7,272,727 shares of common stock, at a price of $2.75 per share to the public. On August 7, 2018, the underwriters exercised in full their option to purchase an additional 1,090,909 shares of common stock at the public offering price of $2.75 per share, less underwriting discounts and commissions. The total gross proceeds from this offering of an aggregate 8,363,636 shares were approximately $23.0 million with net proceeds to the Company of $21.7 million after deducting the underwriting discounts and commissions and other offering expenses payable by the Company. 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, 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. During the year ended December 31, 2017, the Company issued and sold 5.4 million shares of common stock pursuant to the ATM Agreement, for which the Company received net proceeds of approximately $15.7 million, after deducting commissions, fees and expenses of $0.5 million. As of December 31, 2019, the Company may offer and sell shares of the Company’s common stock having an aggregate offering price of up to $45.3 million. Stock Plans 2006 Stock Plan In August 2006, the Company established the 2006 Plan in which 342 shares of common stock were originally reserved for the issuance of incentive stock options, or ISOs, and nonstatutory stock options, or NSOs, to employees, directors or consultants of the Company. In February 2008, an additional 375 shares of common stock were reserved for issuance under the 2006 Plan and, in November 2009, an additional approximately 1.4 million shares of common stock were reserved for issuance under the 2006 Plan. Per the 2006 Plan, the exercise price of ISOs and NSOs granted to a stockholder who at the time of grant owns stock representing more than 10% of the voting power of all classes of the stock of the Company could not be less than 110% of the fair value per share of the underlying common stock on the date of grant. Effective upon the execution and delivery of the underwriting agreement for the Company’s IPO, no additional stock options or other stock awards may be granted under the 2006 Plan. 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 Incentive Plan. As of February 10, 2011, no more awards may be granted under the 2006 Plan, although all outstanding stock options and other stock awards previously granted under the 2006 Plan will continue to remain subject to the terms of the 2006 Plan. The initial aggregate number of shares of the Company’s common stock that were issuable pursuant to stock awards under the 2011 Incentive Plan was approximately 1.9 million shares. The number of shares of common stock reserved for issuance under the 2011 Incentive Plan 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. The term of any option granted under the 2011 Incentive Plan is determined by the Board of Directors on the date of grant but shall not be longer than 10 years. Options under the 2011 Equity Incentive Plan generally vest over four years, and all options expire after 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. 2011 Employee Stock Purchase Plan Additionally, in January 2011, the Board of Directors adopted, and the Company’s stockholders approved, the 2011 Employee Stock Purchase Plan, or the ESPP. As of December 31, 2019, there were 655,420 shares available for issuance under the ESPP. In January 2020, an additional 1,591,462 shares were authorized for issuance under the 2011 Incentive Plan. The number of shares of the Company’s common stock reserved for issuance under the ESPP automatically increased on January 1 of each year, starting January 1, 2012 and continuing through January 1, 2020, in an amount equal to the lower of ( 1 ) 2% of the total number of shares of the Company’s common stock outstanding on December 31 of the preceding calendar year, or ( 2 ) a number of shares of common stock as determined by the Board of Directors. If a purchase right granted under the ESPP terminates without having been exercised, the shares of the Company’s common stock not purchased under such purchase right will be available for issuance under the ESPP. In the year ended December 31, 2019, there were 203,469 shares issued under the ESPP. The weighted average fair value of shares issued under the ESPP in 2019, 2018 and 2017 was $2.33, $1.51 and $2.59 per share, respectively.

Note 12 - Stock-based Compensation

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Share-based Payment Arrangement [Text Block]

. Stock-Based Compensation

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

	December 31, 201 9		December 31, 201 8		December 31, 201 7
Cost of goods sold	$	260	$	358	$	324
Research and development		920		1,970		1,901
Selling, general and administrative		3,877		2,840		2,069
Total	$	5,057	$	5,168	$	4,294

The following table summarizes restricted stock unit activity under the

2011

Incentive Plan:

				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

The following table summarizes option activity under the

2011

Incentive Plan and

2006

Plan:

	Number of Stock Options Outstanding			Weighted- Average Exercise Price	Weighted- Average Remaining Contractual Life (Years)		Aggregate Intrinsic Value
							(in thousands)
December 31, 2018	11,422,705		$	3.64
Granted	2,058,128			2.53
Forfeited	(442,979	)		2.57
Expired	(277,413	)		5.31
Exercised	(111,702	)		2.41
December 31, 2019	12,648,739		$	3.47	6.5	$	197
Vested and exercisable options—December 31, 2019	8,583,475		$	3.90	5.6	$	90
Vested and expected to vest—December 31, 2019	12,648,739		$	3.47	6.5	$	197

As of

December

31,

2019,

there were

1,950,652

shares available for future grant under the

2011

Incentive Plan. In

January 2020,

an additional

3,182,924

shares were authorized for issuance under the

2011

Incentive Plan.

Additional information regarding the Company’s stock options outstanding and vested and exercisable as of

December

31,

2019

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
$1.68	-	$2.56		4,469,976		7.7	$	2.24		2,308,859	$	2.21
$2.57	-	$3.92		5,946,276		6.5	$	3.13		4,081,817	$	3.23
$4.08	-	$6.60		1,627,987		4.2	$	5.58		1,588,299	$	5.61
$8.18	-	$10.55		604,500		4.0	$	10.29		604,500	$	10.29
				12,648,739		6.5	$	3.47		8,583,475	$	3.90

The weighted average grant-date fair value of options granted during the years ended

December

31,

2019,

2018

and

2017

was

$1.83,

$1.62

and

$1.91

per share, respectively. As of

December

31,

2019,

total stock-based compensation expense related to unvested options to be recognized in future periods was

$6.4

million which is expected to be recognized over a weighted-average period of

2.4

years. The grant date fair value of shares vested during the years ended

December

31,

2019,

2018

and

2017

was

$4.4

million,

$4.9

million and

$3.5

million, respectively. The total intrinsic value of options exercised during the years ended

December

31,

2019,

2018

and

2017

was

$0.1

million,

$0.2

million and

$40

thousand, respectively.

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

	Year Ended December 31,
	201 9			201 8			201 7
Expected term (in years)		6.0			5.9			5.7
Risk-free interest rate	1.5%	-	2.5%	2.5%	-	3.1%	1.82%	-	2.09%
Expected volatility		85%			83%			73%
Expected dividend rate		0%			0%			0%

Note 13 - Net Loss Per Share of Common Stock

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Earnings Per Share [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, 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,
	201 9		201 8		201 7
ESPP, RSUs and stock options to purchase common stock		13,798,797		11,797,960		8,767,783
Common stock warrants		176,679		—		176,730

Note 14 - Accrued Liabilities

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Accounts Payable and Accrued Liabilities Disclosure [Text Block]

. Accrued Liabilities

Accrued liabilities consist of the following (in thousands):

	December 31,
	201 9		201 8
Accrued compensation and employee benefits	$	3,796	$	3,611
Inventory and other contract manufacturing accruals		752		234
Other accrued liabilities		980		695
Total accrued liabilities	$	5,528	$	4,540

Note 15 - 401(k) Plan	12 Months Ended
Note 15 - 401(k) Plan	Dec. 31, 2019
Notes to Financial Statements
Pension and Other Postretirement Benefits Disclosure [Text Block]	1 5 . 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 for the year ended December 31, 2019 and $0.3 million for each of the years ended December 31, 2018 and 2017.

Note 16 - Income Taxes

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Income Tax Disclosure [Text Block]

. Income Taxes

The Company recorded a provision for income taxes of

$3.0

thousand and

$2.0

thousand during the years ended

December 31, 2019

and

2018,

respectively, and a benefit for income taxes of

$0.7

million during the year ended

December 31, 2017.

Net deferred tax assets as of

December

31,

2019

and

2018

consist of the following (in thousands):

	December 31, 201 9			December 31, 201 8
Deferred tax assets:
Accruals and other	$	3,672		$	3,263
Research credits		7,275			7,275
Net operating loss carryforward		52,361			39,082
Section 59(e) R&D expenditures		8,933			10,387
Deferred revenue		21,324			20,689
Total deferred tax assets		93,565			80,696
Valuation allowance		(93,565	)		(80,696	)
Net deferred tax assets	$	—		$	—

Reconciliations of the statutory federal income tax to the Company’s effective tax during the years ended

December

31,

2019,

2018

and

2017

are as follows (in thousands):

	Year Ended December 31,
	201 9			2018			2017
Tax at statutory federal rate	$	(11,180	)	$	(9,901	)	$	(17,751	)
State tax—net of federal benefit		(2,538	)		(792	)		350
General business credits		—			(500	)		(316	)
Stock options		800			1,048			42
Other		7			295			(19	)
Change in valuation allowance		12,914			9,852			(17,110	)
Tax reform – tax rate change		—			—			34,103
Provision (benefit) for income taxes	$	3		$	2		$	(701	)

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

$12.9

million and

$9.9

million, and decreased by

$17.1

million during the years ended

December 31, 2019,

2018

and

2017,

respectively.

As of

December

31,

2019,

the Company had federal net operating loss carryforwards of

$212.4

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

$97.5

million generated in

2019

and

2018

will carryforward indefinitely but are subject to the

80%

taxable income limitation. As of

December

31,

2019,

the Company had state net operating loss carryforwards of

$113.5

million, which begin to expire in

2028.

As of

December 31, 2017,

the Company had a federal alternative minimum tax credit carryover of

$0.7

million which was refundable under the tax reform enacted on

December 22, 2017,

$0.3

million of which was received during the year ended

December 31, 2019,

$0.1

million of which is now classified as Tax receivable on the Company’s balance sheet and

$0.3

million of which is classified as a Long-term tax receivable.

As of

December

31,

2019,

the Company had federal research credit carryovers of

$6.5

million, which begin to expire in

2026.

As of

December

31,

2019,

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,

2019,

2018

and

2017

is as follows (in thousands):

	Year Ended December 31,
	2019		2018		2017
Unrecognized benefit—beginning of period	$	2,635	$	2,365	$	2,162
Gross increases—prior period tax positions		—		57		—
Gross increases—current period tax positions		—		213		203
Unrecognized benefit—end of period	$	2,635	$	2,635	$	2,365

The entire amount of the unrecognized tax benefits would

not

impact the Company’s effective tax rate if recognized.

There were

accrued interest or penalties related to unrecognized tax benefits in the years ended

December 31, 2019,

2018

and

2017.

The Company files income tax returns in the United States, California, and other states. The tax years

2005

through

2014,

and

2016

through

2019,

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

months of this reporting date of its uncertain tax positions.

Note 17 - Subsequent Event	12 Months Ended
Note 17 - Subsequent Event	Dec. 31, 2019
Notes to Financial Statements
Subsequent Events [Text Block]	1 7 . Subsequent Event Merger Agreement On March 15, 2020, the Company entered into the Agreement and Plan of Merger with Tetraphase Pharmaceuticals, Inc., or Tetraphase, and Consolidated Merger Sub, Inc., a Delaware corporation and indirect wholly owned subsidiary of the Company, or Merger Sub. Pursuant to the merger agreement, (i) each share of Tetraphase common stock issued and outstanding immediately prior to the effective time of the merger will automatically be converted into the right to receive 0.6303 shares of the Company’s common stock, subject to certain adjustments pursuant to the terms of the merger agreement, and a contingent value right, or CVR, that could provide up to an additional aggregate $12.5 million to Tetraphase stockholders upon the achievement of net sales of XERAVA™ of $20 million, $35 million and $55 million within the applicable timeframes, and as soon as year-end 2021; and (ii) Merger Sub will merge with and into Tetraphase, with Tetraphase continuing as the surviving entity and a wholly owned subsidiary of the Company. The merger agreement has been approved by the board of directors of the Company and Tetraphase. The closing of the merger is expected in the second quarter of 2020 subject to customary closing conditions, including, among others, (i) the adoption of the Agreement and Plan of Merger by a majority of the stockholders of Tetraphase; (ii) the absence of (A) any temporary restraining order, preliminary or permanent injunction or other order issued by any court of competent jurisdiction enjoining or otherwise preventing the consummation of the merger or (B) any applicable law that makes consummation of the merger illegal; (iii) the absence of certain legal proceedings to which a governmental body is a party relating to the merger; (iv) subject to certain qualifications, the accuracy of the representations and warranties of the parties and compliance by the parties with their respective obligations under the merger agreement; (v) the absence of any material adverse effect on Tetraphase or the Company since the date of the merger agreement; (vi) the registration statement on Form S- 4 to register the Company’s common stock to be issued in the merger being declared effective by the SEC; and (vii) a minimum Tetraphase net cash balance. AcelRx shareholders will own approximately 85.4% of the combined company, and Tetraphase shareholders will own approximately 14.6% on a pro forma, fully diluted basis, giving effect to all dilutive securities at the time of announcement, and excluding any settlement of the CVR through issuance of AcelRx common stock. Co-Promotion Agreement On March 15, 2020, the Company entered into the Co-Promotion Agreement with Tetraphase to co-promote DSUVIA and Tetraphases’s XERAVA™ (eravacycline), which is FDA approved for the treatment of complicated intra-abdominal infections. Under the terms of this agreement, each company is responsible for maintaining compliance under the agreed marketing and promotion plan and achieving a minimum number of sales calls for each product. Either party can terminate the agreement with 15 months written notice. In the event of a change of control, or CoC, of either party, the CoC party will be subject to meeting certain performance standards, and if these performance standards are not met, then a royalty of 10% of net sales on the CoC party’s product will be payable to the non-CoC party until the end of the agreement. The non-CoC party will also be able to solicit the employees of CoC party in the event of a change of control and have the right to terminate the agreement with one month’s written notice. 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 to more efficiently commercialize DSUVIA in connection with the Tetraphase commercial team. The Company has eliminated 30 positions, mainly within the commercial organization. The headcount reduction will be completed in the first quarter of 2020. The Company estimates that it will incur aggregate severance and related charges of approximately $0.5 million in the first quarter of 2020. The Company expects that this headcount reduction will result in cost savings of approximately $8 million on an annualized basis. These estimates are subject to a number of assumptions, and actual results may differ. The Company may also incur additional costs not currently contemplated due to events that may occur as a result of, or that are associated with, the reduction.

Note 18 - Unaudited Quarterly Financial Data

12 Months Ended

Dec. 31, 2019

Notes to Financial Statements

Quarterly Financial Information [Text Block]

18.

Unaudited Quarterly Financial Data

The following table sets forth certain unaudited quarterly financial data for the

eight

quarters ended

December

31,

2019.

The unaudited information set forth below has been prepared on the same basis as the audited information and includes all adjustments necessary to present fairly the information set forth herein. The operating results for any quarter are

not

indicative of results for any future period. All data is in thousands except per share data.

	201 9												201 8
	Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
Revenues	$	265		$	941		$	608		$	475		$	343		$	818		$	377		$	613
Operating costs and expenses	$	12,583		$	14,302		$	14,142		$	15,467		$	8,612		$	7,971		$	9,705		$	11,590
Net loss	$	(13,674	)	$	(12,412	)	$	(12,731	)	$	(14,423	)	$	(11,592	)	$	(10,541	)	$	(12,458	)	$	(12,558	)
Net loss per share (basic and diluted)	$	(0.17	)	$	(0.16	)	$	(0.16	)	$	(0.18	)	$	(0.23	)	$	(0.20	)	$	(0.21	)	$	(0.18	)

Significant Accounting Policies (Policies)

12 Months Ended

Dec. 31, 2019

Accounting Policies [Abstract]

Business Description of Entity [Policy Text Block]

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 in Europe) and Zalviso

, are

both 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,

June 2018,

first

quarter of

2019.

In geographies where AcelRx decides

not

to commercialize products by itself, including for DZUVEO in Europe, 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

DSUVIA/DZUVEO

DSUVIA, known as DZUVEO in Europe, approved by the FDA in

November 2018

and approved by the EC in

June 2018,

not

Zalviso

Zalviso delivers

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

trials already completed in the Zalviso NDA resubmission.

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 grants Grünenthal rights to commercialize the Zalviso PCA system, or the Product, in the

September 2015,

the EC approved 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,

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 Amended Agreements.

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,

November 2018

and the Company began its commercial launch of DSUVIA in the

first

quarter of

2019.

As a result, 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.

Basis of Accounting, Policy [Policy Text Block]

Basis of Presentation

Reclassification, Policy [Policy Text Block]

Reclassifications

December 31, 2018,

the amounts reported in the Consolidated Balance Sheets as deferred rent and contingent put option liability have been reclassified to other long-term liabilities at

December 31, 2018,

and Zalviso product sales revenue has been reclassified to product sales from contract and other collaboration in the Consolidated Statements of Comprehensive Loss.

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

“Liability Related to Sale of Future Royalties” for additional information.

Use of Estimates, Policy [Policy Text Block]

Use of Estimates

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.

Fair Value Measurement, Policy [Policy Text Block]

Fair Value of Financial Instruments

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

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

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

Concentration of Risk

The Company invests cash that is currently

not

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 and Zalviso drug cartridge and device components, including the controller, the dispenser kit and the accessories.

DSUVIA is available in the U.S. for distribution primarily through a limited number of wholesalers and is

not

available in retail pharmacies. Zalviso is sold in Europe by the Company’s collaboration partner, Grünenthal. Revenue and accounts receivable are concentrated with these customers.

Receivable [Policy Text Block]

Accounts Receivable,

The Company has receivables from its distributors and collaboration partner, Grünenthal. To date, the Company has

not

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, 2019

is collectible.

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

November 2018.

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

Property and Equipment

three

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

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

Impairment of Long-Lived Assets

not

may

determine that it is

Contingent Put Option, Policy [Policy Text Block]

Contingent put option

“Long-Term Debt”.

Lessee, Leases [Policy Text Block]

Leases

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.

not

may

be required for items such as initial direct costs paid or incentives received.

longer recognizes deferred rent on the balance sheet.

Revenue [Policy Text Block]

Revenue from Contracts with Customers

Beginning

January

2018,

the Company has followed the provisions of Accounting Standards Codification, or ASC, Topic

606,

Revenue from Contracts with Customers

Product sales revenue

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

606

may

●

Distributor Fees – The Company offers contractually determined fees to its distributors.

●

Returns – The Company allows its distributors to return product for credit up to

months after its 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.

●

Prompt Pay Discounts – The Company offers cash discounts to its distributors, generally

not

require a high degree of judgment because the amounts are settled within a relatively short period of time.

Contract and other

collaboration

revenue

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.

Transaction Price

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.

Allocation of Consideration

Timing of Recognition

may

Cost of Goods and Service [Policy Text Block]

Cost of Goods Sold

Cost of goods sold for product revenue includes

third

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

Advertising Cost [Policy Text Block]

Advertising

Expenses

Advertising costs are expensed as incurred. Advertising expenses were

$1.1

million,

$0.5

million and

$0.0

million for the years ended

December 31, 2019,

2018

and

2017,

respectively, and are included in selling, general and administrative expenses in the Consolidated Statements of Comprehensive Loss.

Share-based Payment Arrangement, Director [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

January 1, 2017,

the Company adopted ASU

2016

and elected to recognize forfeitures when they occur using a modified retrospective approach, which did

not

have a material impact on its Consolidated Financial Statements.

Interest Expense, Policy [Policy Text Block]

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

September 2015,

$65.0

$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

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

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

Income Tax, Policy [Policy Text Block]

Income Taxes

not.

Earnings Per Share, Policy [Policy Text Block]

Net Loss per Share of Common Stock

“Net Loss per Share of Common Stock”.

New Accounting Pronouncements, Policy [Policy Text Block]

Recently Adopted Accounting Pronouncement

August 29, 2018,

the Financial Accounting Standards Board, or FASB, issued ASU

No.

2018

15,

“

Intangibles – Goodwill and Other – Internal Use Software (Subtopic

350

)”

The amendments in ASU

No.

2018

ASU

No.

2018

is effective for public business entities for fiscal years beginning after

December 15, 2019,

and interim periods within those fiscal years. Early adoption is permitted, including adoption in any interim period for which financial statements have

not

been issued. Entities can choose to adopt the new guidance (

) prospectively to eligible costs incurred on or after the date this guidance is

first

applied or (

) retrospectively. The Company early adopted ASU

No.

2018

effective

January 1, 2019

under the prospective method, which did

not

have a material effect on the Company’s results of operations, financial condition or cash flows.

August 2018,

the U.S. Securities and Exchange Commission, or SEC, published Release

No.

10532,

Disclosure Update and Simplification,

January 1, 2019.

February 2016,

the FASB issued ASU

No.

2016

02,

Leases (Topic

842

)

, which establishes a new lease accounting model for lessees. In

January,

July

and

December 2018,

the FASB issued additional amendments to the new lease guidance relating to, transition, and clarification. The

July 2018

amendment, ASU

No.

2018

11,

Leases (Topic

842

): Targeted Improvements

months. Disclosure requirements have been enhanced with the objective of enabling financial statement users to assess the amount, timing, and uncertainty of cash flows arising from leases. ASU

No.

2016

became effective for the Company on

January 1, 2019.

)

not

reassess the lease classification for any expired or existing leases, (

)

not

reassess the treatment of initial direct costs as they related to existing leases, and (

)

not

The adoption of the new leases standard resulted in the following adjustments to the Consolidated Balance Sheets as of

January 1, 2019 (

in thousands):

	Increase/(Decrease)
Operating lease right-of-use assets	$	4,730
Accrued liabilities (a)	$	(100	)
Operating lease liabilities	$	484
Operating lease liabilities, net of current portion	$	4,610
Deferred rent, net of current portion	$	(416	)
Accumulated deficit (b)	$	(153	)

	(a)	Represents current portion of Deferred rent reclassified to Operating lease liabilities.

	(b)	Represents cumulative-effect adjustment upon adoption of ASU No. 2016 - 02.

The adoption of ASU

No.

2016

02,

the new leases standard, did

not

impact previously reported financial results because the impact to prior periods was reflected as a cumulative-effect adjustment to the accumulated deficit under the optional transition method.

Recently Issued Accounting Pronouncements

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

is effective for the Company beginning

January 1, 2023,

with early adoption allowed beginning

January 1, 2020.

May 2019,

the FASB issued ASU

2019

05,

“

Financial Instruments – Credit Losses”

, or ASU

2019

05,

2016

13.

Management is currently assessing the date of adoption and the impact ASU

2016

and ASU

2019

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 and cash flows.

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

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of New Accounting Pronouncements and Changes in Accounting Principles [Table Text Block]

	Increase/(Decrease)
Operating lease right-of-use assets	$	4,730
Accrued liabilities (a)	$	(100	)
Operating lease liabilities	$	484
Operating lease liabilities, net of current portion	$	4,610
Deferred rent, net of current portion	$	(416	)
Accumulated deficit (b)	$	(153	)

Note 2 - Investments and Fair Value Measurement (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Cash, Cash Equivalents and Investments [Table Text Block]

	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

	As of December 31, 2018
	Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses		Fair Value
Cash and cash equivalents:
Cash	$	2,037	$	—	$	—	$	2,037
Money market funds		1,436		—		—		1,436
U.S. government agency securities		10,181		—		—		10,181
Commercial paper		74,321		—		—		74,321
Total cash and cash equivalents		87,975		—		—		87,975

Short-term investments:
U.S. government agency securities		1,497		—		—		1,497
Commercial paper		16,243		—		—		16,243
Total short-term investments		17,740		—		—		17,740
Total cash, cash equivalents and short-term investments	$	105,715	$	—	$	—	$	105,715

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

	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

	As of December 31, 2018
	Fair Value		Level I		Level II		Level III
Assets
Money market funds	$	1,436	$	1,436	$	—	$	—
U.S. government agency securities		11,678		—		11,678		—
Commercial paper		90,564		—		90,564		—
Total assets measured at fair value	$	103,678	$	1,436	$	102,242	$	—
Liabilities
Contingent put option liability	$	121	$	—	$	—	$	121
Total liabilities measured at fair value	$	121	$	—	$	—	$	121

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

	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

	Year Ended December 31, 2018
Fair value—beginning of period	$	207
Change in fair value of contingent put option associated with Amended Loan Agreement		(86	)
Fair value—end of period	$	121

- Definition

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 (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Inventory, Current [Table Text Block]

	As of December 31,
	2019		2018
Raw materials	$	1,153	$	694
Work-in-process		593		160
Finished goods		1,549		—
Inventories	$	3,295	$	854

Note 4 - Property and Equipment (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Property, Plant and Equipment [Table Text Block]

	As of December 31,
	2019			2018
Laboratory equipment	$	4,389		$	3,972
Leasehold improvements		4,616			4,469
Computer equipment and software		1,749			237
Construction in process		11,949			10,593
Tooling		1,109			1,109
Furniture and fixtures		292			47

		24,104			20,427
Less accumulated depreciation and amortization		(9,552	)		(8,944	)
Property and equipment, net	$	14,552		$	11,483

Note 5 - Revenue from Contracts with Customers (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Disaggregation of Revenue [Table Text Block]

	December 31,
	201 9		201 8		201 7
Product sales:
DSUVIA	$	377	$	—	$	—
Zalviso		1,453		825		6,673
Total product sales		1,830		825		6,673
Contract and other collaboration:
DoD Contract revenue		—		838		852
Non-cash royalty revenue related to Royalty Monetization (See Note 8)		312		289		151
Royalty revenue		104		96		50
Other revenue		43		103		269
Total revenues from contract and other collaboration		459		1,326		1,322
Total revenue	$	2,289	$	2,151	$	7,995

Contract with Customer, Asset and Liability [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	$	3,463	$	—	$	(315	)	$	3,148
Deferred revenue – Other		—		96		—			96
Deferred revenue	$	3,463	$	96	$	(315	)	$	3,244

	Year ended December 31, 2019		Year ended December 31, 2018
Amounts included in contract liabilities at the beginning of the period:
Performance obligations satisfied – Amended Agreements	$	315	$	362
New activities in the period from performance obligations satisfied:
Performance obligations satisfied – Amended Agreements		1,181		566
Total revenue from performance obligations satisfied	$	1,496	$	928

Note 6 - Long-term Debt (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	As of December 31,
	2019
Present value of the face amount of $1.0 million	$	899
Less: current portion		463
Long-term debt, net of current portion	$	436

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

2020	$	6,936
2021		10,429
2022		9,187
2023		5,530
Total payments		32,082
Less amount representing interest		(4,792	)
Notes payable, gross		27,290
Less: Unamortized portion of EOT Fee		(978	)
Less: Unamortized discount on notes payable		(1,165	)
Long-term debt		25,147
Less current portion		(4,630	)
Long-term debt, net of current portion	$	20,517

- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28541-108399

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21506-112644

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=114775744&loc=d3e28551-108399

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21521-112644

Reference 7: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21538-112644

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=109259400&loc=d3e21475-112644

+ Details

Note 7 - Leases (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Lease, Cost [Table Text Block]

	Year Ended December 31, 2019
Operating lease costs	$	1,360
Sublease income		(596	)
Net lease costs	$	764

	Year Ended December 31, 2019
Cash paid for amounts included in the measurement of lease liabilities
Operating cash flows used for operating leases	$	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, 2019
Weighted-average remaining term – operating lease (in years)		4.08
Weighted-average discount rate – operating lease		11.72	%

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

Year:
2020	$	1,268
2021		1,305
2022		1,345
2023		1,386
2024		116
Total future minimum lease payments		5,420
Less imputed interest		(810	)
Total	$	4,610

Operating lease liabilities	$	970
Operating lease liabilities, net of current portion		3,640
Total lease liability	$	4,610

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

Year:
2020	$	593
2021		610
2022		629
2023		648
2024		54
Total future minimum sublease payments	$	2,534

Prepaid expenses and other current assets	$	78
Other assets		354
Total rent receivable	$	432

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

12 Months Ended

Dec. 31, 2019

Notes Tables

Other Liabilities [Table Text Block]

	Year ended December 31, 201 9			Period from inception to December 31, 201 9
Liability related to sale of future royalties — beginning balance	$	93,679		$	—
Proceeds from sale of future royalties		—			61,184
Non-cash royalty revenue		(307	)		(684	)
Non-cash interest (income) expense recognized		(1,337	)		31,535
Liability related to sale of future royalties as of December 31, 2019		92,035			92,035
Less: current portion		(352	)		(352	)
Liability related to sale of future royalties — net of current portion	$	91,683		$	91,683

Note 12 - Stock-based Compensation (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	December 31, 201 9		December 31, 201 8		December 31, 201 7
Cost of goods sold	$	260	$	358	$	324
Research and development		920		1,970		1,901
Selling, general and administrative		3,877		2,840		2,069
Total	$	5,057	$	5,168	$	4,294

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

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, 2018	11,422,705		$	3.64
Granted	2,058,128			2.53
Forfeited	(442,979	)		2.57
Expired	(277,413	)		5.31
Exercised	(111,702	)		2.41
December 31, 2019	12,648,739		$	3.47	6.5	$	197
Vested and exercisable options—December 31, 2019	8,583,475		$	3.90	5.6	$	90
Vested and expected to vest—December 31, 2019	12,648,739		$	3.47	6.5	$	197

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
$1.68	-	$2.56		4,469,976		7.7	$	2.24		2,308,859	$	2.21
$2.57	-	$3.92		5,946,276		6.5	$	3.13		4,081,817	$	3.23
$4.08	-	$6.60		1,627,987		4.2	$	5.58		1,588,299	$	5.61
$8.18	-	$10.55		604,500		4.0	$	10.29		604,500	$	10.29
				12,648,739		6.5	$	3.47		8,583,475	$	3.90

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

	Year Ended December 31,
	201 9			201 8			201 7
Expected term (in years)		6.0			5.9			5.7
Risk-free interest rate	1.5%	-	2.5%	2.5%	-	3.1%	1.82%	-	2.09%
Expected volatility		85%			83%			73%
Expected dividend rate		0%			0%			0%

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

12 Months Ended

Dec. 31, 2019

Notes Tables

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

	Year Ended December 31,
	201 9		201 8		201 7
ESPP, RSUs and stock options to purchase common stock		13,798,797		11,797,960		8,767,783
Common stock warrants		176,679		—		176,730

Note 14 - Accrued Liabilities (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Accrued Liabilities [Table Text Block]

	December 31,
	201 9		201 8
Accrued compensation and employee benefits	$	3,796	$	3,611
Inventory and other contract manufacturing accruals		752		234
Other accrued liabilities		980		695
Total accrued liabilities	$	5,528	$	4,540

Note 16 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Schedule of Deferred Tax Assets [Table Text Block]

	December 31, 201 9			December 31, 201 8
Deferred tax assets:
Accruals and other	$	3,672		$	3,263
Research credits		7,275			7,275
Net operating loss carryforward		52,361			39,082
Section 59(e) R&D expenditures		8,933			10,387
Deferred revenue		21,324			20,689
Total deferred tax assets		93,565			80,696
Valuation allowance		(93,565	)		(80,696	)
Net deferred tax assets	$	—		$	—

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

	Year Ended December 31,
	201 9			2018			2017
Tax at statutory federal rate	$	(11,180	)	$	(9,901	)	$	(17,751	)
State tax—net of federal benefit		(2,538	)		(792	)		350
General business credits		—			(500	)		(316	)
Stock options		800			1,048			42
Other		7			295			(19	)
Change in valuation allowance		12,914			9,852			(17,110	)
Tax reform – tax rate change		—			—			34,103
Provision (benefit) for income taxes	$	3		$	2		$	(701	)

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

	Year Ended December 31,
	2019		2018		2017
Unrecognized benefit—beginning of period	$	2,635	$	2,365	$	2,162
Gross increases—prior period tax positions		—		57		—
Gross increases—current period tax positions		—		213		203
Unrecognized benefit—end of period	$	2,635	$	2,635	$	2,365

Note 18 - Unaudited Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2019

Notes Tables

Quarterly Financial Information [Table Text Block]

	201 9												201 8
	Q1			Q2			Q3			Q4			Q1			Q2			Q3			Q4
Revenues	$	265		$	941		$	608		$	475		$	343		$	818		$	377		$	613
Operating costs and expenses	$	12,583		$	14,302		$	14,142		$	15,467		$	8,612		$	7,971		$	9,705		$	11,590
Net loss	$	(13,674	)	$	(12,412	)	$	(12,731	)	$	(14,423	)	$	(11,592	)	$	(10,541	)	$	(12,458	)	$	(12,558	)
Net loss per share (basic and diluted)	$	(0.17	)	$	(0.16	)	$	(0.16	)	$	(0.18	)	$	(0.23	)	$	(0.20	)	$	(0.21	)	$	(0.18	)

Note 1 - Organization and Summary of Significant Accounting Policies (Details Textual) - USD ($) $ in Thousands		1 Months Ended	12 Months Ended			51 Months Ended
	Sep. 18, 2015	Sep. 30, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Promt Payment Discount			2.00%
Advertising Expense			$ 1,100	$ 500	$ 0
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				$ 61,184

Note 1 - Organization and Summary of Significant Accounting Policies - Adjustments for Adoption of New Lease Standard (Details) - USD ($)
$ in Thousands

Dec. 31, 2019

Jan. 01, 2019

Dec. 31, 2018

Operating lease right-of-use assets

$ 3,928

Accrued liabilities

5,528

4,540

Operating lease liabilities

970

Operating lease liabilities, net of current portion

3,640

Accumulated deficit

$ (398,106)

$ (345,019)

Accounting Standards Update 2016-02 [Member]

Operating lease right-of-use assets

$ 4,730

Accrued liabilities

^[1]

(100)

Operating lease liabilities

484

Operating lease liabilities, net of current portion

4,610

Deferred rent, net of current portion

(416)

Accumulated deficit

^[2]

$ (153)

[1]	Represents current portion of Deferred rent reclassified to Operating lease liabilities.
[2]	Represents cumulative-effect adjustment upon adoption of ASU No. 2016-02.

Note 2 - Investments and Fair Value Measurement (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Available-for-sale Securities, Gross, Unrealized Gain (Loss) Accumulated In Investments	$ 0	$ 0
Available-for-sale Securities, Gross Realized Gain (Loss), Total	0	0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities, Total	0	0
Debt Securities, Available-for-sale, Realized Gain (Loss), Total	0	0
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, Net of Tax	$ 0	$ 0

Note 2 - Investments and Fair Value Measurement - Summary of Cash, Cash Equivalents and Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Amortized Cost	$ 66,137	$ 105,715
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	66,137	105,715
Cash and Cash Equivalents [Member]
Amortized Cost	14,684	87,975
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	14,684	87,975
Cash and Cash Equivalents [Member] \| Cash [Member]
Amortized Cost	1,957	2,037
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	1,957	2,037
Cash and Cash Equivalents [Member] \| Money Market Funds [Member]
Amortized Cost	598	1,436
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	598	1,436
Cash and Cash Equivalents [Member] \| Commercial Paper [Member]
Amortized Cost	12,129	74,321
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	12,129	74,321
Cash and Cash Equivalents [Member] \| U.S. Government Agency Securities [Member]
Amortized Cost		10,181
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value		10,181
Cash and Cash Equivalents [Member] \| Corporate Debt Securities [Member]
Amortized Cost	10,054
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	10,054
Marketable Securities [Member]
Amortized Cost	51,453	17,740
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	51,453	17,740
Marketable Securities [Member] \| Commercial Paper [Member]
Amortized Cost	27,131	16,243
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	27,131	16,243
Marketable Securities [Member] \| U.S. Government Agency Securities [Member]
Amortized Cost	14,268	1,497
Gross Unrealized Gains
Gross Unrealized Losses
Fair Value	$ 14,268	$ 1,497

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, 2019	Dec. 31, 2018
Assets, fair value	$ 64,180	$ 103,678
Liabilities, fair value	437	121
Contingent Put Option Liability [Member]
Liabilities, fair value	437	121
Fair Value, Inputs, Level 1 [Member]
Assets, fair value	598	1,436
Liabilities, fair value
Fair Value, Inputs, Level 1 [Member] \| Contingent Put Option Liability [Member]
Liabilities, fair value
Fair Value, Inputs, Level 2 [Member]
Assets, fair value	63,582	102,242
Liabilities, fair value
Fair Value, Inputs, Level 2 [Member] \| Contingent Put Option Liability [Member]
Liabilities, fair value
Fair Value, Inputs, Level 3 [Member]
Assets, fair value
Liabilities, fair value	437	121
Fair Value, Inputs, Level 3 [Member] \| Contingent Put Option Liability [Member]
Liabilities, fair value	437	121
Money Market Funds [Member]
Assets, fair value	598	1,436
Money Market Funds [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value	598	1,436
Money Market Funds [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value
Money Market Funds [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value
U.S. Government Agency Obligations [Member]
Assets, fair value	14,268	11,678
U.S. Government Agency Obligations [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value
U.S. Government Agency Obligations [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value		11,678
U.S. Government Agency Obligations [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	14,268
U.S. Government Agency Securities [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value
Commercial Paper [Member]
Assets, fair value	39,260	90,564
Commercial Paper [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value
Commercial Paper [Member] \| Fair Value, Inputs, Level 2 [Member]
Assets, fair value	39,260	90,564
Commercial Paper [Member] \| Fair Value, Inputs, Level 3 [Member]
Assets, fair value
Corporate Debt Securities [Member]
Assets, fair value	10,054
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member]
Assets, fair value
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

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, 2019	Dec. 31, 2018
Fair value, Beginning of period	$ 121	$ 207
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)
Change in fair value of contingent put option associated with Amended Loan Agreement		(86)
Fair value, End of period	$ 437	$ 121

Note 3 - Inventories (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Inventory Write-down	$ 951		$ 369
ZALVISO [Member]
Inventory Write-down			$ 400

Note 3 - Inventories - Inventory Components (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Raw materials	$ 1,153	$ 694
Work-in-process	593	160
Finished goods	1,549
Inventories, net	$ 3,295	$ 854

Note 4 - Property and Equipment (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Depreciation, Total	$ 0.9	$ 0.5	$ 1.7

Note 4 - Property and Equipment - Components of Property and Equipment (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Property and Equipment, Gross	$ 24,104	$ 20,427
Less accumulated depreciation and amortization	(9,552)	(8,944)
Property and equipment, net	14,552	11,483
Laboratory Equipment [Member]
Property and Equipment, Gross	4,389	3,972
Leasehold Improvements [Member]
Property and Equipment, Gross	4,616	4,469
Computer Equipment and Software [Member]
Property and Equipment, Gross	1,749	237
Construction in Progress [Member]
Property and Equipment, Gross	11,949	10,593
Tooling [Member]
Property and Equipment, Gross	1,109	1,109
Furniture and Fixtures [Member]
Property and Equipment, Gross	$ 292	$ 47

Note 5 - Revenue from Contracts with Customers (Details Textual) - USD ($) $ in Millions	Dec. 31, 2019	Jul. 17, 2015	May 11, 2015
Revenue Recognition Milestone Method Agreed, Additional Amount, Based On Efforts And Targets		$ 194.5
Government Contract Receivable			$ 17.0
Deferred Revenue, Noncurrent, Total	$ 3.1
Deferred Revenue, Current, Total	$ 0.3
Based upon Successful Regulatory and Product Development Efforts [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount, Based On Efforts And Targets		28.5
Based upon Net Sales Target Achievements [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount, Based On Efforts And Targets		$ 166.0

Note 5 - Revenue from Contracts with Customers - Disaggregation of Revenue (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue	$ 2,289	$ 2,151	$ 7,995
DSUVIA [Member]
Revenue	377
ZALVISO [Member]
Revenue	1,453	825	6,673
Product [Member]
Revenue	1,830	825	6,673
Department of Defense [Member]
Revenue		838	852
Non-cash Royalty [Member]
Revenue	312	289	151
Royalty [Member]
Revenue	104
Royalty Revenue [Member]
Revenue		96	50
Contract and Other Revenue [Member]
Revenue	43	103	269
Contract and Other Collaboration [Member]
Revenue	$ 459	$ 1,326	$ 1,322

Note 5 - Revenue from Contracts with Customers - Changes in Contract Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Contract Liabilities: Deferred Revenue	$ 3,463
Contract Liabilities: Deferred Revenue, Additions	96
Contract Liabilities: Deferred Revenue, Deductions	(315)
Contract Liabilities: Deferred Revenue	3,244	$ 3,463
Revenue	2,289	2,151	$ 7,995
ZALVISO [Member]
Contract Liabilities: Deferred Revenue	3,463
Contract Liabilities: Deferred Revenue, Additions
Contract Liabilities: Deferred Revenue, Deductions	(315)
Contract Liabilities: Deferred Revenue	3,148	3,463
Revenue	1,453	825	$ 6,673
Amended License Agreement [Member]
Amounts included in contract liabilities at the beginning of the period: Performance obligations satisfied – Amended Agreements	315	362
New activities in the period from performance obligations satisfied: Performance obligations satisfied – Amended Agreements	1,181	566
Revenue	1,496	928
Product and Service, Other [Member]
Contract Liabilities: Deferred Revenue
Contract Liabilities: Deferred Revenue, Additions	96
Contract Liabilities: Deferred Revenue, Deductions
Contract Liabilities: Deferred Revenue	$ 96

Note 6 - Long-term Debt (Details Textual) - USD ($)				1 Months Ended	12 Months Ended
Note 6 - Long-term Debt (Details Textual) - USD ($)	Aug. 01, 2019	May 30, 2019	Dec. 16, 2013	Dec. 31, 2013	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Oct. 01, 2017	Mar. 02, 2017	Dec. 31, 2016	Sep. 30, 2016	Sep. 18, 2015
Repayments of Long-term Debt, Total					$ 3,470,000	$ 7,718,000	$ 3,514,000
Interest Expense, Total					2,535,000	2,217,000	3,316,000
Long-term Debt, Total					25,147,000
Amortization of Debt Discount (Premium)					712,000	613,000	1,265,000
Loan Agreement with Oxford Finance LLC [Member]
Debt Instrument, Face Amount		$ 25,000,000
Debt Instrument, Final Payment, Percentage of Aggregate Principal Amount		5.00%
Repayments of Long-term Debt, Total		$ 8,900,000
Fair Value of Contingent Put Option, Liability					400,000
Interest Expense, Total					1,900,000
Proceeds from Debt, Net of Issuance Costs and Repayment of Debt		$ 15,900,000
Debt Instrument, Interest Rate, Base Percentage		2.50%
Prepayment Charge, Percentage of Outstanding Balance, Before May 30,2020		2.00%
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
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%
Amortization of Debt Discount (Premium)					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
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]
Debt Instrument, Face Amount									$ 20,500,000
Debt Instrument, Final Payment, Percentage of Aggregate Principal Amount									6.50%
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)
Fair Value of Contingent Put Option, Liability						100,000
Long-term Line of Credit, Total						12,000,000
Interest Expense, Total					600,000	$ 2,200,000	$ 3,300,000
Hercules Loan and Security Agreement [Member] \| First Tranche [Member]
Debt Instrument, Face Amount									$ 20,500,000
Amended and Restated Loan and Security Agreement [Member]
Long-term Debt Maturities Balloon Payments								$ 1,700,000
Debt Instrument, Variable Rate Threshold									9.55%
Debt Instrument, Percentage Used to Calculate Variable Rate									3.50%
Amended and Restated Loan and Security Agreement [Member] \| Prime Rate [Member]
Debt Instrument, Interest Rate, Effective Percentage										9.55%
Site Readiness Agreement [Member]
Debt Instrument, Face Amount					$ 1,000,000
Debt Instrument, Interest Rate, Effective Percentage					13.61%
Long-term Debt, Gross					$ 1,500,000
Long-term Debt, Total					899,000
Debt Instrument, Periodic Payment, Principal	$ 500,000
Total Obligation Under Leasehold Agreement	$ 2,000,000
Hercules Warrants [Member]
Common Stock Warrants Exercised			176,730	176,730
Class of Warrant or Right, Exercise Price of Warrants or Rights			$ 6.79	$ 6.79							$ 3.07	$ 3.88
Warrant In Connection with Oxford Finance Loan Agreement [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights		$ 2.83
Class of Warrant or Right, Number of Securities Called by Warrants or Rights		176,679
Loan Agreement with Oxford Finance LLC [Member]
Long-term Debt, Total					$ 24,200,000

Note 6 - Long-term Debt - Balance of Future Payments (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Long-term debt	$ 25,147
Long-term debt, current portion	4,630	$ 8,611
Long-term debt, net of current portion	20,517	$ 3,380
Site Readiness Agreement [Member]
Long-term debt	899
Long-term debt, current portion	463
Long-term debt, net of current portion	$ 436

Note 6 - Long-term Debt - Balance of Future Payments (Details) (Parentheticals) $ in Millions	Dec. 31, 2019 USD ($)
Site Readiness Agreement [Member]
Face Value	$ 1

Note 6 - Long-term Debt - Outstanding Future Payments of Long-term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
2020	$ 6,936
2021	10,429
2022	9,187
2023	5,530
Total payments	32,082
Less amount representing interest	(4,792)
Notes payable, gross	27,290
Less: Unamortized portion of EOT Fee	(978)
Less: Unamortized discount on notes payable	(1,165)
Long-term debt	25,147
Less current portion	(4,630)	$ (8,611)
Long-term debt, net of current portion	$ 20,517	$ 3,380

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, 2019	Dec. 31, 2018	Dec. 31, 2017	Feb. 16, 2019
Lessee, Operating Lease, Renewal Term		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			$ 242,000
Increase (Decrease) in Operating Lease Liabilities	(24,000)			$ (701,000)
Lessee, Operating Lease, Notice Period		1 year 180 days
Lessee, Operating Lease, Annual Overhead Fee Payments		$ 200,000
Increase (Decrease) in Right-of-use Assets	$ (24,000)

Note 7 - Leases - Operating Lease Costs (Details) - USD ($)		12 Months Ended
	Jan. 02, 2019	Dec. 31, 2019
Operating lease costs		$ 1,360,000
Sublease income		(596,000)
Net lease costs		764,000
Operating cash flows used for operating leases		1,084,000
Lessee, Operating Sublease, Initial Tenant Incentive Allowance Transfered from Operating Lease	$ 200,000	242,000
Right-of-use assets obtained in exchange for new operating lease liabilities		$ 4,730,000
Weighted-average remaining term – operating lease (in years) (Year)		4 years 29 days
Weighted-average discount rate – operating lease		11.72%

Note 7 - Leases - Maturities of Lease Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
2020	$ 1,268
2021	1,305
2022	1,345
2023	1,386
2024	116
Total future minimum lease payments	5,420
Less imputed interest	(810)
Total	4,610
Operating lease liabilities	970
Operating lease liabilities, net of current portion	3,640
Total lease liability	$ 4,610

Note 7 - Leases - Future Minimum Sublease Payments (Details) $ in Thousands	Dec. 31, 2019 USD ($)
2020	$ 593
2021	610
2022	629
2023	648
2024	54
Total future minimum sublease payments	2,534
Rent receivable	432
Prepaid Expenses and Other Current Assets [Member]
Rent receivable	78
Other Assets [Member]
Rent receivable	$ 354

Note 8 - Liability Related to Sale of Future Royalties (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		1 Months Ended	3 Months Ended	12 Months Ended
	Sep. 18, 2015	Sep. 30, 2015	Jun. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Proceeds From Sale of Royalty and Milestone Rights	$ 65,000	$ 65,000
Royalty Arrangment Maximum Payments	$ 195,000	$ 195,000
Prospective Average Rate for Remaining Term of the Agreement			4.20%
Estimate Future Payments Receivable Over Remaining Life of Arrangment				$ 20,000
Contingent Gain (Loss) on Royalty Monetization Arrangement				$ 45,000
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				$ 8,100
Net Income (Loss) Per Share, Change Estimate on Liability Related to Sale of Future Royalties				$ 0.10
Effective Annual Interest Rate				1.40%	11.60%	13.60%
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	$ 43,500
MAA Approval [Member]
Revenue Recognition Milestone Method Agreed, Additional Amount	15,000
PDL [Member]
Proceeds From Sale of Royalty and Milestone Rights	$ 61,200
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	$ 35,600
AcelRX [Member] \| First Four Commercial Milestones [Member]
Commercial Milestones Value Maximum Amount Available	$ 44,500

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			51 Months Ended
	Sep. 30, 2015	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2019
Liability related to sale of future royalties — beginning balance		$ 93,679
Proceeds from sale of future royalties	$ 61,200				61,184
Non-cash royalty revenue		(307)			(684)
Non-cash interest (income) expense recognized		(1,337)	$ 10,341	$ 10,721	31,535
Liability related to sale of future royalties as of December 31, 2019		92,035	93,679		92,035
Less: current portion		(352)	(392)		(352)
Liability related to sale of future royalties — net of current portion		$ 91,683	$ 93,287		$ 91,683

Note 9 - Warrants (Details Textual) $ / shares in Units, $ in Millions		1 Months Ended		12 Months Ended
	Dec. 16, 2013 $ / shares shares	Dec. 31, 2013 $ / shares shares	Jun. 30, 2012 USD ($) $ / shares shares	Dec. 31, 2017 USD ($) shares	Dec. 31, 2019 shares	May 30, 2019 USD ($) $ / shares shares	Dec. 31, 2018 shares	Sep. 30, 2016 $ / shares	Sep. 18, 2015 $ / shares
Warrant In Connection with Oxford Finance Loan Agreement [Member]
Class of Warrant or Right, Number of Securities Called by Warrants or Rights						176,679
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares						$ 2.83
Warrants and Rights Outstanding, Term						10 years
Warrants and Rights Outstanding \| $						$ 0.4
Class of Warrant or Right, Outstanding					176,679
Warrant In Connection with Oxford Finance Loan Agreement [Member] \| Measurement Input, Exercise Price [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares						$ 2.83
Warrant In Connection with Oxford Finance Loan Agreement [Member] \| Measurement Input, Share Price [Member]
Warrants and Rights Outstanding, Measurement Input						2.66
Warrant In Connection with Oxford Finance Loan Agreement [Member] \| Measurement Input, Expected Term [Member]
Warrants and Rights Outstanding, Measurement Input						10
Warrant In Connection with Oxford Finance Loan Agreement [Member] \| Measurement Input, Risk Free Interest Rate [Member]
Warrants and Rights Outstanding, Measurement Input						2.22
Warrant In Connection with Oxford Finance Loan Agreement [Member] \| Measurement Input, Price Volatility [Member]
Warrants and Rights Outstanding, Measurement Input						80.22
Warrant In Connection with Oxford Finance Loan Agreement [Member] \| Measurement Input, Expected Dividend Rate [Member]
Warrants and Rights Outstanding, Measurement Input						0
Hercules Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares	$ 6.79	$ 6.79						$ 3.07	$ 3.88
Class of Warrant or Right, Outstanding							176,730
Common Stock Warrants Exercised	176,730	176,730
PIPE Warrants [Member]
Class of Warrant or Right, Exercise Price of Warrants or Rights \| $ / shares			$ 3.40
Class of Warrant or Right, Outstanding			2,630,103	512,456
Warrant Exercisable Term			5 years
Warrants Vesting Condition Description			50.00%
2012 Private Placement [Member]
Fair Value of Warrant Upon Execution of Securities Purchase Agreement \| $			$ 5.8
2012 Private Placement [Member] \| Nonoperating Income (Expense) [Member]
Fair Value Adjustment of Warrants \| $				$ 0.3

Note 11 - Stockholders' Equity (Details Textual) - USD ($)							1 Months Ended				9 Months Ended	12 Months Ended
	Jan. 01, 2020	May 09, 2019	Nov. 14, 2018	Aug. 07, 2018	Jul. 16, 2018	Jun. 21, 2016	Aug. 07, 2018	Nov. 30, 2009	Feb. 29, 2008	Aug. 31, 2006	Sep. 30, 2019	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2011	Jan. 31, 2020
Proceeds from Issuance of Common Stock												$ 1,233,000	$ 81,525,000	$ 15,694,000
Employee Stock Purchase Plan, Shares Issued, Weighted Average Fair Value												$ 2.33	$ 1.51	$ 2.59
2006 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized										342,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized								1,400,000	375,000
2006 Equity Incentive Plan [Member] \| Minimum [Member]
Common Stock Voting Rights Percentage										10.00%
2006 Equity Incentive Plan [Member] \| Maximum [Member]
Fair Value of Common Stock as Percentage of Option Exercise Price										110.00%
2011 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other Than Options, Outstanding															1,900,000
Stock Option Plan Option Reserve Annual Increase as Percentage of Outstanding Shares Allowed															4.00%
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period															4 years
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant												1,950,652
2011 Equity Incentive Plan [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	3,182,924
2011 Equity Incentive Plan [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period															10 years
Employee Stock Purchase Plan (ESPP) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized												655,420
Share-based Payment Award, Number of Shares Authorized															2.00%
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant												203,469
Employee Stock Purchase Plan (ESPP) [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized																1,591,462
Public Offering [Member]
Proceeds from Issuance Initial Public Offering						$ 40,000,000						$ 80,000,000
Underwritten Public Offering [Member]
Stock Issued During Period, Shares, New Issues			14,603,173	1,090,909	7,272,727		8,363,636
Shares Issued, Price Per Share			$ 3.15	$ 2.75	$ 2.75		$ 2.75
Proceeds from Issuance of Common Stock			$ 46,000,000				$ 23,000,000
Proceeds from Issuance of Common Stock, Net			$ 43,100,000				$ 21,700,000
ATM Agreement [Member]
Stock Issued During Period, Shares, New Issues												500,000
Proceeds from Issuance of Common Stock												$ 1,200,000
Aggregate Offering Price, Increase During Period		$ 40,000,000
Payments of Stock Issuance Costs												$ 32,000
Aggregate Offering Price, Maximum											$ 45,300,000
ATM Agreement 2016 [Member]
Stock Issued During Period, Shares, New Issues													4,400,000	5,400,000
Proceeds from Issuance of Common Stock, Net													$ 16,800,000	$ 15,700,000
Payments of Stock Issuance Costs													$ 400,000	$ 500,000

Note 12 - Stock-based Compensation (Details Textual) - USD ($) $ / shares in Units, $ in Thousands		12 Months Ended
	Jan. 01, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 1.83	$ 1.62	$ 1.91
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total		$ 6,400
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition			2 years 146 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value		4,400	$ 4,900	$ 3,500
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		$ 100	$ 200	$ 40
2011 Equity Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		1,950,652
2011 Equity Incentive Plan [Member] \| Subsequent Event [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	3,182,924

Note 12 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-based compensation expense	$ 5,057	$ 5,168	$ 4,294
Cost of Sales [Member]
Stock-based compensation expense	260	358	324
Research and Development Expense [Member]
Stock-based compensation expense	920	1,970	1,901
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 3,877	$ 2,840	$ 2,069

Note 12 - Stock-based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Restricted stock units outstanding, January 1, 2019 (in shares) \| shares
Restricted stock units outstanding, January 1, 2019 (in dollars per share) \| $ / shares
Granted (in shares) \| shares	1,029,085
Granted (in dollars per share) \| $ / shares	$ 2.53
Vested (in shares) \| shares
Vested (in dollars per share) \| $ / shares
Forfeited (in shares) \| shares	(40,440)
Forfeited (in dollars per share) \| $ / shares	$ 2.54
Restricted stock units outstanding, December 31, 2019 (in shares) \| shares	988,645
Restricted stock units outstanding, December 31, 2019 (in dollars per share) \| $ / shares	$ 2.53

Note 12 - Stock-based Compensation - Option Activity (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2019 USD ($) $ / shares shares
Outstanding (in shares) \| shares	11,422,705
Outstanding (in dollars per share) \| $ / shares	$ 3.64
Granted (in shares) \| shares	2,058,128
Granted, weighted-average exercise price (in dollars per share) \| $ / shares	$ 2.53
Forfeited (in shares) \| shares	(442,979)
Forfeited, weighted-average exercise price (in dollars per share) \| $ / shares	$ 2.57
Expired (in shares) \| shares	(277,413)
Expired, weighted-average exercise price (in dollars per share) \| $ / shares	$ 5.31
Exercised (in shares) \| shares	(111,702)
Exercised, weighted-average exercise price (in dollars per share) \| $ / shares	$ 2.41
Outstanding (in shares) \| shares	12,648,739
Outstanding, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.47
Outstanding, weighted-average remaining contractual life (Year)	6 years 182 days
Outstanding, aggregate intrinsic value \| $	$ 197
Vested and exercisable options (in shares) \| shares	8,583,475
Vested and exercisable options, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.90
Vested and exercisable options, weighted-average remaining contractual life (Year)	5 years 219 days
Vested and exercisable options, aggregate intrinsic value \| $	$ 90
Vested and expected to vest (in shares) \| shares	12,648,739
Vested and expected to vest, weighted-average exercise price (in dollars per share) \| $ / shares	$ 3.47
Vested and expected to vest, weighted-average remaining contractual life (Year)	6 years 182 days
Vested and expected to vest, aggregate intrinsic value \| $	$ 197

Note 12 - Stock-based Compensation - Stock Options Outstanding, Vested and Exercisable (Details) - $ / shares	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Number of Stock Options Outstanding (in shares)	12,648,739	11,422,705
Weighted-average Remaining Contractual LIfe (Year)	6 years 182 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.47	$ 3.64
Shares Subject to Stock Options (in shares)	8,583,475
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.90
Exercise Price Range 1 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	1.68
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 2.56
Number of Stock Options Outstanding (in shares)	4,469,976
Weighted-average Remaining Contractual LIfe (Year)	7 years 255 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 2.24
Shares Subject to Stock Options (in shares)	2,308,859
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 2.21
Exercise Price Range 2 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	2.58
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 3.92
Number of Stock Options Outstanding (in shares)	5,946,276
Weighted-average Remaining Contractual LIfe (Year)	6 years 182 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.13
Shares Subject to Stock Options (in shares)	4,081,817
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 3.23
Exercise Price Range 3 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	4.08
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 6.60
Number of Stock Options Outstanding (in shares)	1,627,987
Weighted-average Remaining Contractual LIfe (Year)	4 years 73 days
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 5.58
Shares Subject to Stock Options (in shares)	1,588,299
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 5.61
Exercise Price Range 4 [Member]
Exercise Price Range, Lower Range Limit (in dollars per share)	8.18
Exercise Price Range, Upper Range Limit (in dollars per share)	$ 10.55
Number of Stock Options Outstanding (in shares)	604,500
Weighted-average Remaining Contractual LIfe (Year)	4 years
Options Outstanding, Weighted-average Exercise Price Per Share (in dollars per share)	$ 10.29
Shares Subject to Stock Options (in shares)	604,500
Options Vested and Exercisable, Weighted-average Exercise Price Per Share (in dollars per share)	$ 10.29

Note 12 - Stock-based Compensation - Assumptions to Calculate Fair Value of Each Employee Stock Option (Details)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Expected term (Year)	6 years	5 years 328 days	5 years 255 days
Expected volatility	85.00%	83.00%	73.00%
Expected dividend rate	0.00%	0.00%	0.00%
Minimum [Member]
Expected term (Year)
Risk-free interest rate	1.50%	2.50%	1.82%
Expected volatility
Expected dividend rate
Maximum [Member]
Expected term (Year)
Risk-free interest rate	2.50%	3.10%	2.09%
Expected volatility
Expected dividend rate

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, 2019	Dec. 31, 2018	Dec. 31, 2017
RSU's, ESPP, and Employee Stock Options [Member]
Antidilutive securities (in shares)	13,798,797	11,797,960	8,767,783
Warrant [Member]
Antidilutive securities (in shares)	176,679		176,730

Note 14 - Accrued Liabilities - Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Accrued compensation and employee benefits	$ 3,796	$ 3,611
Inventory and other contract manufacturing accruals	752	234
Other accrued liabilities	980	695
Total accrued liabilities	$ 5,528	$ 4,540

Note 15 - 401(k) Plan (Details Textual) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Defined Contribution Plan, Employer Discretionary Contribution Percentage	4.00%
Contributions by Employer to Postemployment Benefit Obligations	$ 0.5	$ 0.3	$ 0.3

Note 16 - Income Taxes (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Tax Expense (Benefit), Total	$ 3	$ 2	$ (701)
SEC Schedule, 12-09, Valuation Allowances and Reserves, Period Increase (Decrease), Total	12,900	9,900	(17,100)
Income Taxes Receivable, Current	88	352
Income Taxes Receivable, Noncurrent	263	351
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
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	212,400		114,900
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	300		700
Income Taxes Receivable, Current	100
Income Taxes Receivable, Noncurrent			$ 300
Domestic Tax Authority [Member] \| Research Tax Credit Carryforward [Member]
Tax Credit Carryforward, Amount	6,500
Domestic Tax Authority [Member] \| Tax Year 2019 [Member]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Period Increase (Decrease), Total	97,500
Domestic Tax Authority [Member] \| Tax Year 2018 [Member]
SEC Schedule, 12-09, Valuation Allowances and Reserves, Period Increase (Decrease), Total		$ 97,500
State and Local Jurisdiction [Member]
Operating Loss Carryforwards, Total	113,500
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, 2019	Dec. 31, 2018
Accruals and other	$ 3,672	$ 3,263
Research credits	7,275	7,275
Net operating loss carryforward	52,361	39,082
Section 59(e) R&D expenditures	8,933	10,387
Deferred revenue	21,324	20,689
Total deferred tax assets	93,565	80,696
Valuation allowance	(93,565)	(80,696)
Net deferred tax assets		$ 0

Note 16 - Income Taxes - Reconciliation of Statutory Federal Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax at statutory federal rate	$ (11,180)	$ (9,901)	$ (17,751)
State tax—net of federal benefit	(2,538)	(792)	350
General business credits		(500)	(316)
Stock options	800	1,048	42
Other	7	295	(19)
Change in valuation allowance	12,914	9,852	(17,110)
Tax reform – tax rate change			34,103
Provision (benefit) for income taxes	$ 3	$ 2	$ (701)

Note 16 - Income Taxes - Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Unrecognized benefit—beginning of period	$ 2,635	$ 2,365	$ 2,162
Gross increases—prior period tax positions		57
Gross increases—current period tax positions		213	203
Unrecognized benefit—end of period	$ 2,635	$ 2,635	$ 2,365

Note 17 - Subsequent Event (Details Textual) $ in Millions	Mar. 16, 2020	Mar. 31, 2020 USD ($)	Mar. 15, 2020 USD ($) shares
Employee Severance [Member] \| Forecast [Member]
Restructuring and Related Cost, Expected Cost, Total		$ 0.5
Restructuring and Related Cost, Expected Annual Savings		$ 8.0
Subsequent Event [Member]
Co-Promotion Agreement, Percent of Net Sales to be Paid as Royalty Contingent on Performance Standards			10.00%
Subsequent Event [Member] \| Employee Severance [Member]
Restructuring and Related Cost, Number of Positions Eliminated	30
Subsequent Event [Member] \| Tetraphase [Member]
Business Combination, Number of Common Shares Called by Each Right \| shares			0.6303
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High			$ 12.5
Business Acquisition, Percentage of Voting Interests Acquired			85.40%
Business Acquisition, Percentage of Voting Interests Remaining With Acquired Entity Shareholders			14.60%
Subsequent Event [Member] \| Tetraphase [Member] \| First Sales Benchmark [Member]
Business Combination, Contingent Consideration Arrangements, Contingent Achievement Benchmarks			$ 20.0
Subsequent Event [Member] \| Tetraphase [Member] \| Second Sales Benchmark [Member]
Business Combination, Contingent Consideration Arrangements, Contingent Achievement Benchmarks			35.0
Subsequent Event [Member] \| Tetraphase [Member] \| Third Sales Benchmark [Member]
Business Combination, Contingent Consideration Arrangements, Contingent Achievement Benchmarks			$ 55.0

Note 18 - Unaudited Quarterly Financial Data - Quarterly Financial Data (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Total revenue	$ 475	$ 608	$ 941	$ 265	$ 613	$ 377	$ 818	$ 343
Total operating costs and expenses	15,467	14,142	14,302	12,583	11,590	9,705	7,971	8,612
Net loss	$ (14,423)	$ (12,731)	$ (12,412)	$ (13,674)	$ (12,558)	$ (12,458)	$ (10,541)	$ (11,592)	$ (53,240)	$ (47,149)	$ (51,508)
Net loss per share of common stock, basic and diluted (in dollars per share)	$ (0.18)	$ (0.16)	$ (0.16)	$ (0.17)	$ (0.18)	$ (0.21)	$ (0.20)	$ (0.23)	$ (0.67)	$ (0.81)	$ (1.10)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References + Details

Note 12 - Stock-based Compensation - Restricted Stock Activity (Details) - Restricted Stock Units (RSUs) [Member]	12 Months Ended
	Dec. 31, 2019 $ / shares shares
Restricted stock units outstanding, January 1, 2019 (in shares) \| shares
Restricted stock units outstanding, January 1, 2019 (in dollars per share) \| $ / shares
Granted (in shares) \| shares	1,029,085
Granted (in dollars per share) \| $ / shares	$ 2.53
Vested (in shares) \| shares
Vested (in dollars per share) \| $ / shares
Forfeited (in shares) \| shares	(40,440)
Forfeited (in dollars per share) \| $ / shares	$ 2.54
Restricted stock units outstanding, December 31, 2019 (in shares) \| shares	988,645
Restricted stock units outstanding, December 31, 2019 (in dollars per share) \| $ / shares	$ 2.53