Talphera (TLPH) 10-K 7 Mar 16 2015 FY Annual report Financial data

Document And Entity Information

Document And Entity Information - USD ($)	12 Months Ended
	Dec. 31, 2015	Feb. 24, 2016	Jun. 30, 2015
Document and Entity Information [Abstract]
Entity Registrant Name	ACELRX PHARMACEUTICALS INC
Trading Symbol	acrx
Document Type	10-K
Current Fiscal Year End Date	--12-31
Entity Common Stock, Shares Outstanding		45,273,772
Entity Public Float			$ 145,535,000
Amendment Flag	false
Entity Central Index Key	1,427,925
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Accelerated Filer
Entity Well-known Seasoned Issuer	No
Document Period End Date	Dec. 31, 2015
Document Fiscal Year Focus	2,015
Document Fiscal Period Focus	FY

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($)	Dec. 31, 2015	Dec. 31, 2014
Current Assets:
Cash and cash equivalents	$ 107,922,000	$ 60,038,000
Short-term investments	5,542,000	15,312,000
Accounts receivable, net	3,286,000	0
Inventories	466,000
Prepaid expenses and other current assets	1,731,000	948,000
Total current assets	118,947,000	76,298,000
Property and equipment, net	8,610,000	9,818,000
Restricted cash	178,000	250,000
Other assets	50,000	50,000
Total Assets	127,785,000	86,416,000
Current Liabilities:
Accounts payable	1,561,000	2,431,000
Accrued liabilities	3,956,000	3,654,000
Long-term debt, current portion	4,541,000	6,859,000
Deferred revenue, current portion	2,604,000	787,000
Liability related to the sale of future royalties, current portion	118,000
Total current liabilities	12,780,000	13,731,000
Deferred rent, net of current portion	245,000	529,000
Long-term debt, net of current portion	16,381,000	18,015,000
Deferred revenue, net of current portion	593,000	1,626,000
Liability related to the sale of future royalties, net of current portion	63,494,000
Contingent put option liability	266,000	282,000
Warrant liability	913,000	5,577,000
Total liabilities	$ 94,672,000	$ 39,760,000
Commitments and Contingencies
Stockholders’ Equity:
Common stock, $0.001 par value—100,000,000 shares authorized as of December 31, 2015 and December 31, 2014; 45,273,772 and 43,712,363 shares issued and outstanding as of December 31, 2015 and December 31, 2014	$ 45,000	$ 43,000
Additional paid-in capital	236,274,000	225,423,000
Accumulated deficit	(203,205,000)	(178,806,000)
Accumulated other comprehensive loss	(1,000)	(4,000)
Total stockholders’ equity	33,113,000	46,656,000
Total Liabilities and Stockholders’ Equity	$ 127,785,000	$ 86,416,000

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parentheticals) - $ / shares	Dec. 31, 2015	Dec. 31, 2014
Common stock, par value (in Dollars per share)	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	100,000,000
Common stock, shares issued	45,273,772	43,712,363
Common stock, shares outstanding	45,273,772	43,712,363

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Revenue:
Collaboration agreement	$ 14,857,000	$ 5,217,000	$ 27,370,000
Contract and other	4,406,000		2,132,000
Total revenue	19,263,000	5,217,000	29,502,000
Operating costs and expenses:
Cost of goods sold	1,770,000
Research and development	22,488,000	24,520,000	26,292,000
General and administrative	14,203,000	18,346,000	9,877,000
Restructuring costs	756,000
Total operating costs and expenses	39,217,000	42,866,000	36,169,000
Loss from operations	(19,954,000)	(37,649,000)	(6,667,000)
Other (expense) income:
Interest expense	(2,977,000)	(2,639,000)	(1,518,000)
Interest income and other income (expense), net	1,720,000	6,935,000	(15,241,000)
Non-cash interest expense on liability related to sale of future royalties	(2,428,000)
Total other (expense) income	(3,685,000)	4,296,000	(16,759,000)
Net loss before income taxes	(23,639,000)	(33,353,000)	(23,426,000)
Provision for income taxes	(760,000)	0	0
Net loss	(24,399,000)	(33,353,000)	(23,426,000)
Other comprehensive income (loss):
Unrealized gains (losses) on available for sale securities	3,000	(5,000)
Comprehensive loss	$ (24,396,000)	$ (33,358,000)	$ (23,426,000)
Net loss per share of common stock, basic (in Dollars per share)	$ (0.55)	$ (0.77)	$ (0.59)
Net loss per share of common stock, diluted (in Dollars per share)	$ (0.60)	$ (0.91)	$ (0.59)
Shares used in computing net loss per share of common stock, basic (in Shares)	44,300,099	43,427,111	39,746,678
Shares used in computing net loss per share of common stock, diluted –see Note 14 (in Shares)	44,468,440	44,322,297	39,746,678

Consolidated Statements of Stoc

Consolidated Statements of Stockholders’ Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance as of December 31, 2012 at Dec. 31, 2012	$ 37	$ 155,836	$ (122,027)	$ 1	$ 33,847
Balance as of December 31, 2012 (in Shares) at Dec. 31, 2012	37,055,027
Issuance of Warrants		1,130			1,130
Stock-based compensation		3,479			3,479
Issuance of common stock upon exercise of stock options and in connection with restricted stock units	$ 1	1,276			1,277
Issuance of common stock upon exercise of stock options and in connection with restricted stock units (in Shares)	520,365
Issuance of common stock upon exercise of stock warrants	$ 1	8,689			$ 8,690
Issuance of common stock upon exercise of stock warrants (in Shares)	1,050,062				808,078
Issuance of common stock upon ESPP purchase		219			$ 219
Issuance of common stock upon ESPP purchase (in Shares)	55,126
Issuance of common stock upon underwritten public offering, net of offering-related costs	$ 4	47,939			47,943
Issuance of common stock upon underwritten public offering, net of offering-related costs (in Shares)	4,370,000
Net loss			(23,426)		(23,426)
Balance at Dec. 31, 2013	$ 43	218,568	(145,453)	1	73,159
Balance (in Shares) at Dec. 31, 2013	43,050,580
Stock-based compensation		4,440			4,440
Issuance of common stock upon exercise of stock options and in connection with restricted stock units		1,507			1,507
Issuance of common stock upon exercise of stock options and in connection with restricted stock units (in Shares)	487,124
Issuance of common stock upon exercise of stock warrants		546			$ 546
Issuance of common stock upon exercise of stock warrants (in Shares)	91,488				91,488
Issuance of common stock upon ESPP purchase		362			$ 362
Issuance of common stock upon ESPP purchase (in Shares)	83,171
Change in unrealized gains and losses on investments				(5)	(5)
Net loss			(33,353)		(33,353)
Balance at Dec. 31, 2014	$ 43	225,423	(178,806)	(4)	46,656
Balance (in Shares) at Dec. 31, 2014	43,712,363
Stock-based compensation		5,010			5,010
Issuance of common stock upon exercise of stock options	$ 1	2,769			$ 2,770
Issuance of common stock upon exercise of stock options (in Shares)	938,497				938,497
Issuance of common stock upon exercise of stock warrants	$ 1	2,543			$ 2,544
Issuance of common stock upon exercise of stock warrants (in Shares)	527,101				527,101
Modification of warrants		100			$ 100
Issuance of common stock upon ESPP purchase		429			429
Issuance of common stock upon ESPP purchase (in Shares)	95,811
Change in unrealized gains and losses on investments				3	3
Net loss			(24,399)		(24,399)
Balance at Dec. 31, 2015	$ 45	$ 236,274	$ (203,205)	$ (1)	$ 33,113
Balance (in Shares) at Dec. 31, 2015	45,273,772

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
CASH FLOWS FROM OPERATING ACTIVITIES:
Net loss	$ (24,399)	$ (33,353)	$ (23,426)
Adjustments to reconcile net loss to net cash used in operating activities:
Non-cash interest expense on liability related to royalty monetization	2,428
Depreciation and amortization	1,984	866	593
Amortization of premium/discount on investments, net	114	216	202
Interest expense related to debt financing	897	553	442
Stock-based compensation	5,010	4,440	3,479
Revaluation of put option and PIPE warrant liabilities	(2,136)	(7,040)	14,071
Loss on extinguishment of debt			1,202
Loss on disposal and impairment of property and equipment	573
Changes in operating assets and liabilities:
Accounts receivable	(3,286)
Inventories	(466)
Prepaid expenses and other assets	(783)	137	1,132
Restricted cash	72		(45)
Accounts payable	(786)	90	106
Accrued liabilities	325	(126)	(760)
Deferred revenue	784	(217)	2,630
Deferred rent	(284)	(22)	(113)
Net cash used in operating activities	(19,953)	(34,456)	(487)
CASH FLOWS FROM INVESTING ACTIVITIES:
Purchase of property and equipment	(1,456)	(5,505)	(3,287)
Purchase of investments	(7,266)	(17,430)	(28,009)
Proceeds from maturities of investments	16,925	17,159	24,376
Net cash provided by (used in) investing activities	8,203	(5,776)	(6,920)
CASH FLOWS FROM FINANCING ACTIVITIES:
Net proceeds from sale of future royalties	61,184
Proceeds from issuance of common stock in equity offerings, net of offering costs			47,943
Proceeds from the issuance of long-term debt		10,000	14,958
Payment of long-term debt	(4,534)		(16,345)
Payment of debt modification transaction costs	(215)
Extinguishment of debt			(437)
Net proceeds from issuance of common stock through equity plans and exercise of warrants	3,199	1,869	1,757
Net cash provided by financing activities	59,634	11,869	47,876
NET INCREASE (DECREASE) IN CASH AND CASH EQUIVALENTS	47,884	(28,363)	40,469
CASH AND CASH EQUIVALENTS—Beginning of period	60,038	88,401	47,932
CASH AND CASH EQUIVALENTS—End of period	107,922	60,038	88,401
SUPPLEMENTAL DISCLOSURES OF CASH FLOW INFORMATION:
Cash paid for interest	2,115	1,752	1,105
Income taxes paid	782
NONCASH INVESTING AND FINANCING ACTIVITIES:
Issuance of common stock upon cashless exercise of warrants	2,544	546	8,428
Issuance of warrants for common stock			1,130
Modification of warrants for common stock	100
Tenant improvement allowance receivable		239
Contingent put option liability			334
Purchases of property and equipment in Accounts payable	$ 98	182
Purchases of property and equipment in Accrued liabilities		$ 23	$ 725

Note 1 - Organization and Summa

Note 1 - Organization and Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2015
Disclosure Text Block [Abstract]
Basis of Presentation and Significant Accounting Policies [Text Block]	1. Organization and Summary of Significant Accounting Policies The Company AcelRx Pharmaceuticals, Inc., or the Company or AcelRx, was incorporated in Delaware on July 13, 2005 as SuRx, Inc., and in January 2006, the Company changed its name to AcelRx Pharmaceuticals, Inc. The Company’s operations are based in Redwood City, California. AcelRx is a specialty pharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of acute pain. AcelRx intends to commercialize its product candidates in the United States and license the development and commercialization rights to its product candidates for sale outside of the United States through strategic partnerships and collaborations. AcelRx may also consider the option to enter into strategic partnerships for its product candidates in the United States. In September 2015, the Company reported that SAP301, a pivotal Phase 3 study for ARX-04 (sufentanil sublingual tablet, 30 mcg), a proprietary, non-invasive, single-use tablet in a disposable, pre-filled single-dose applicator, or SDA, for the treatment of moderate-to-severe acute pain, met primary and secondary endpoints in a multi-center, double-blind, placebo-controlled trial designed to study the short-term treatment of patients with moderate-to-severe acute pain following ambulatory abdominal surgery. In October 2015, we announced the initiation of SAP302, an open-label Phase 3 study of ARX-04 for the treatment of adult patients who present in the emergency room with moderate-to-severe acute pain associated with trauma or injury. The SAP302 study is expected to be completed by the third quarter of 2016. The Company has initiated SAP303, an open-label, single-arm study of ARX-04 in post-operative patients over 40 years of age that will allow for administration of ARX-04 for up to 12 hours. This study is also expected to be completed by the third quarter of 2016. The Company believes ARX-04 may be a candidate for use in a variety of medically supervised settings to manage moderate-to-severe acute pain, including emergency room patients; patients who are recovering from short-stay or ambulatory surgery and do not require more long-term patient-controlled analgesia; post-operative patients who are transitioning from the operating room to the recovery floor; patients being transported by paramedics; and battlefield casualties. The Company’s other late-stage investigational product candidate, Zalviso™, delivers 15 mcg sufentanil sublingually through a non-invasive delivery route via a pre-programmed, patient-controlled analgesia device. In response to the New Drug Application, or NDA, the Company submitted to the U.S. Food and Drug Administration, or FDA, seeking approval for Zalviso, the Company received a Complete Response Letter, or CRL, on July 25, 2014. The FDA has requested an additional clinical study and the Company is planning to begin this study, IAP312, in the first quarter of 2016. On December 16, 2013, AcelRx and Grünenthal GmbH, or Grünenthal, entered into a Collaboration and License Agreement, or the License Agreement, which was amended effective July 17, 2015, or the Amended License Agreement, which grants Grünenthal rights to commercialize Zalviso in the countries of the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia. In September 2015, the European Commission approved the Marketing Authorization Application, or MAA, previously submitted to the European Medicines Agency, or EMA, for Zalviso for the management of acute moderate-to-severe post-operative pain in adult patients. The approval allows Grünenthal to market Zalviso in the 28 European Union member states as well as for the European Economic Area countries, Norway, Iceland and Liechtenstein, or EEA. Also on December 16, 2013, AcelRx and Grünenthal, entered into a related 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 entered into an amendment to the MSA, or the MSA Amendment, and together with the MSA, the Amended MSA, between the Company and Grünenthal, each effective as of July 17, 2015, and together, with the Amended License Agreement, the Amended Agreements. The Company has incurred recurring operating losses and negative cash flows from operating activities since inception and expects to continue to incur negative cash flows. Although Zalviso has been approved for sale in the European Union, 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. As a result, the Company expects to continue to incur negative cash flows. When we refer to "we," "our," "us," the "Company" or "AcelRx" in this document, we mean the current Delaware corporation, or AcelRx Pharmaceuticals, Inc., and its predecessor, as well as its consolidated subsidiary. 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. Refer to “Recently Issued Accounting Standards” below for additional information. 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 monetization transaction 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, or the Royalty Monetization. All intercompany accounts and transactions have been eliminated in consolidation. Refer to Note 8 “Liability Related to Sale of Future Royalties” for additional information. Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying notes. Management evaluates its estimates on an ongoing basis including critical accounting policies. Estimates are based on historical experience and on various other market-specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates. Cash, Cash Equivalents and Marketable Securities 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 and money market instruments. All marketable securities are classified as available-for-sale and consist of U.S. Treasury and U.S. government sponsored enterprise debt securities. These securities are carried at estimated fair value, which is based on quoted market prices or observable market inputs of almost identical assets, with unrealized gains and losses included in accumulated other comprehensive income (loss). The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income or expense. The cost of securities sold is based on specific identification. The Company’s investments are subject to a periodic impairment review for other-than-temporary declines in fair value. The Company’s review includes the consideration of the cause of the impairment including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. When the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other-than-temporary, it reduces the carrying value of the security it holds and records a loss in the amount of such decline. Fair Value of Financial Instruments The Company measures and reports its cash equivalents, investments and financial liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level I—Unadjusted quoted prices in active markets for identical assets or liabilities; Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement. Segment Information The Company operates in a single segment, the development and commercialization of product candidates for the treatment of pain. The Company’s contract 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. 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 the U.S. Treasury and 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 Sheet. The Company relies on a single third-party supplier for the supply of sufentanil, the active pharmaceutical ingredient in Zalviso, and various sole-source third-party contract manufacturer organizations to manufacture the Zalviso drug cartridge and device components, including the controller, the dispenser kit and the accessories. To date, the Company has had only two customers. These two customers account for 100% of the revenues for the years ended December 31, 2015, 2014 and 2013. One of these customers accounted for 84% of the accounts receivable balance as of December 31, 2015. The Company did not have an Accounts receivable balance as of December 31, 2014. 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, 2015 is collectible. Accounts Receivable, Net The Company has receivables from its collaboration partner and the U.S. Department of Defense, or DoD. 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. Inventories Inventories are valued at the lower of cost or market. 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. 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 market approach as that used to value the inventory. Because selling prices to Grünenthal are set to recover only direct costs with minimal mark up, all 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 to five years. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvements or the remaining lease term. Expenditures for repairs and maintenance, which do not extend the useful life of the property and equipment, are expensed as incurred. Upon retirement, the asset cost and related accumulated depreciation are relieved from the accompanying Consolidated Balance Sheets. Gains and losses associated with dispositions are reflected as a component of Other (expense) income 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, purchased equipment and manufacturing-related facility improvements the Company has made at Patheon’s facility in Ohio, are utilized for continued research and development, commercial manufacturing of Zalviso for Grünenthal and potential commercialization of its other product candidates. If the Company does not receive regulatory approval for its other product candidates, the Company may determine that it is no longer probable that the Company will realize the future economic benefit associated with the costs of these assets through future manufacturing activities, and if so, the Company would record an impairment charge associated with these assets. As of September 30, 2015, the Company remeasured on a non-recurring basis a portion of its leasehold improvements in its corporate offices using Level III valuation techniques. The write down to fair value of these long-lived assets resulted in an impairment charge of $0.5 million in the year ended December 31, 2015, which was recorded in interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. As of December 31, 2015, the Company has not written down any additional long-lived assets as a result of impairment. Restricted Cash Under the Company’s facility lease and corporate credit card agreements, the Company is required to maintain letters of credit as security for performance under these agreements. The letters of credit are secured by certificates of deposit in amounts equal to the letters of credit, which are classified as restricted cash on the Consolidated Balance Sheets. Debt Issuance Costs Debt issuance costs, which are included in long-term debt, net of current portion, are amortized as interest expense over the contractual terms of the related credit facilities. Contingent put option The contingent put option associated with the Company’s loan and security agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, 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 additional information regarding the contingent put option, see Note 7 “Long-Term Debt.” Warrants Warrants issued in connection with the Company’s Private Placement, completed in June 2012, are recorded as liabilities as they have the potential for cash settlement upon the occurrence of certain transactions (as defined in the warrant; see Note 9 “Warrants”). Changes in the fair value of the warrants are recognized as interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. Revenue Recognition The Company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured. Collaboration Revenue Collaboration revenue, which is earned under license agreements with third parties, may include nonrefundable license fees, cost reimbursements, research and development services, commercial manufacturing services, contingent development and commercial milestones and royalties. AcelRx accounts for multiple-element arrangements in accordance with ASC Topic 605-25, Revenue Recognition—Multiple-Element Arrangements For revenue agreements with multiple-element arrangements, such as the collaboration and license agreement with Grünenthal, the Company allocates revenue to each non-contingent element based on the relative selling price of each element. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence, or VSOE, of selling price or third-party evidence, or TPE, of selling price. If neither exists the Company uses best estimated selling price, or BESP, for that deliverable. Revenue allocated is then recognized when the four basic revenue recognition criteria are met for each element. VSOE is based on the price charged when the element is sold separately and is the price actually charged for that deliverable. Establishing VSOE may not be possible for the elements of a license arrangement because each arrangement is unique, an arrangement typically consists of multiple elements and AcelRx has limited history of entering into license arrangements. When VSOE cannot be established, AcelRx attempts to establish the selling price of the elements of a license arrangement based on TPE. TPE is determined based on a competitor’s price for similar deliverables when sold separately. AcelRx may not be able to determine TPE for license arrangements, as they contain a significant level of differentiation such that the comparable pricing of a competitor’s license arrangement with similar functionality cannot be obtained, and AcelRx is therefore unable to reliably determine what a similar competitor’s license arrangement’s selling price would be on a standalone basis. When AcelRx is unable to establish the selling price of an element using VSOE or TPE, BESP is utilized in the allocation of the elements of the arrangement. The objective of the BESP is to determine the price at which AcelRx would transact a sale if the element of the license arrangement were sold on a standalone basis. The process for determining BESPs involves management’s judgment. AcelRx’ process considers multiple factors such as discounted cash flows, estimated direct expenses and other costs and available data, which may vary over time, depending upon the circumstances, and relate to each deliverable. If the estimated obligation period of one or more deliverables should change, the future amortization of the revenue would also change. AcelRx recognizes a contingent milestone payment as revenue in its entirety upon our achievement of the milestone. A milestone is substantive if the consideration earned from the achievement of the milestone (i) is consistent with performance required to achieve the milestone or the increase in value to the delivered item, (ii) relates solely to past performance and (iii) is reasonable relative to all of the other deliverables and payments within the arrangement. Contract and Other Revenue In May 2011, the Company received a grant from the USAMRMC to support the development of ARX-04. The grant provided for the reimbursement of qualified expenses for research and development activities as defined under the terms of the grant agreement. Revenue under the grant agreement was recognized when the related qualified research expenses were incurred. In May 2015, the Company entered into the DoD Contract with the USAMRMC to support the development of ARX-04. The DoD Contract provides for the reimbursement of qualified expenses for development, manufacturing, regulatory and clinical costs outlined in the contract in order to submit an NDA to the FDA, including reimbursement for certain personnel and overhead expenses, as defined under the terms of the contract. Revenue under the contract is recognized when the related qualified expenses are incurred. The Company is entitled to reimbursement of overhead costs associated with the study costs incurred under the DoD Contract. The Company estimates this overhead rate by utilizing forecasted expenditures. Final reimbursable overhead expenses are dependent on direct labor and direct reimbursable expenses throughout the life of the DoD Contract, so it may increase or decrease based on actual expenses incurred. Cost of Goods Sold Under the Amended Agreements with Grünenthal, the Company will sell Zalviso to Grünenthal at direct cost with minimal markup and will recognize indirect costs as period costs where they are in excess of normal capacity and not realizable on a lower of cost or market 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. Stock-Based Compensation Compensation expense for all share-based payment awards made to employees and directors, including employee stock options, restricted stock units 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. Estimates of expected life are primarily determined using the simplified method in accordance with guidance provided by the SEC. Such method was utilized as the Company did not believe its historical option exercise experience, which was limited, provided a reasonable basis upon which to estimate expected term. Volatility is derived from historical volatilities of several public companies within AcelRx’s industry that are deemed to be comparable to AcelRx’s business because AcelRx’s has insufficient history on the volatility of its common stock relative to the expected life assumptions used by the Company. 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. Further, the Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual forfeitures differ from those estimates. Restructuring Costs The Company's restructuring costs consist of employee termination benefit costs. Liabilities for costs associated with the cost reduction plan are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the entity notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the future service period. Non-Cash Interest Expense on Liability Related to Sale of Future Royalties In September 2015, the Company sold certain royalty and milestone payment rights from the sales of Zalviso in the European Union by its commercial partner, Grünenthal, pursuant to the Collaboration and License Agreement, dated as of December 16, 2013, as amended, to PDL for an upfront cash purchase price of $65.0 million, referred to as the Royalty Monetization. The Company continues to have 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 the Company’s significant continuing involvement, the Royalty Monetization has been accounted for as a liability that will be amortized using the 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 PDL and payments the Company is required to make to PDL, up to a capped amount of $195.0 million, over the life of the arrangement. The sum of the capped amount of $195.0 million, 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 record interest expense using an estimated interest rate for an arms-length debt transaction. The Company’s estimate of the interest rate under the arrangement is based on the amount of royalty and milestone payments expected to be received by PDL over the life of the arrangement. The Company’s estimate of this total interest expense resulted in an effective annual interest rate of approximately 14%. The Company will periodically assess 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 its 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. 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 PDL agreement. 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, 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 14 “Net Loss per Share of Common Stock.” Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330) Related to Simplifying the Measurement of Inventory In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest

Note 2 - Investments and Fair V

Note 2 - Investments and Fair Value Measurement	12 Months Ended
	Dec. 31, 2015
Investments And Fair Value Measurement Disclosure [Abstract]
Investments And Fair Value Measurement Disclosure [Text Block]	2. Investments and Fair Value Measurement Investments The Company classifies its marketable securities as available-for-sale and records its investments at fair value. Available-for-sale securities are carried at estimated fair value based on quoted market prices or observable market inputs of almost identical assets, with the unrealized holding gains and losses included in accumulated other comprehensive income. Marketable securities which have maturities beyond one year as of the end of the reporting period are classified as non-current. The table below summarizes the Company’s cash, cash equivalents and investments (in thousands): As of December 31, 2015 Amortized Cost Gross Unrealized Gross Unrealized Fair Cash and cash equivalents: Cash $ 83,112 $ — $ — $ 83,112 U.S. government agency securities 24,809 1 — 24,810 Total cash and cash equivalents 107,921 1 — 107,922 Marketable securities: U.S. government agency securities 5,544 — (2 ) 5,542 Total marketable securities 5,544 — (2 ) 5,542 Total cash, cash equivalents and investments $ 113,465 $ 1 $ (2 ) $ 113,464 As of December 31, 2014 Amortized Cost Gross Unrealized Gross Unrealized Fair Cash and cash equivalents: Cash $ 60,005 $ — $ — $ 60,005 Money market funds 33 — — 33 Total cash and cash equivalents 60,038 — — 60,038 Marketable securities: U.S. government agency securities 15,316 — (4 ) 15,312 Total marketable securities 15,316 — (4 ) 15,312 Total cash, cash equivalents and investments $ 75,354 $ — $ (4 ) $ 75,350 None of the available-for-sale securities held by the Company had material unrealized losses and there were no realized losses for the years ended December 31, 2015 and 2014. There were no other-than-temporary impairments for these securities as of December 31, 2015 or 2014. No gross realized gains or losses were recognized on the available-for-sale securities and, accordingly, there were no amounts reclassified out of accumulated other comprehensive income to earnings during the years ended December 31, 2015 and 2014. As of December 31, 2015 and 2014, 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 Level II assets and Level III liabilities. Level I securities include highly liquid money market funds and are valued based on quoted market prices. 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 and U.S. government agency obligations. As of December 31, 2015 and December 31, 2014, the Company held, in addition to Level I and Level II assets, a contingent put option liability associated with the Company’s Amended and Restated Loan and Security Agreement, or the Amended Loan Agreement, with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, which amends and restates the loan and security agreement with Hercules dated as of June 29, 2011, or the Original Loan Agreement, and which was classified as a Level III liability. See Note 7 “Long-Term Debt” for further description . The Company’s estimate of fair value of the contingent put option liability was determined by using a risk-neutral valuation model, wherein the fair value of the underlying debt facility is estimated both with and without the presence of the default provisions, holding all other assumptions constant. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option. 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. As of December 31, 2015 and 2014, the Company also held a Level III liability associated with warrants, or PIPE warrants, issued in connection with the Company’s private placement equity offering, completed in June 2012. For a detailed description, see Note 11 “Stockholders’ Equity.” The PIPE warrants are considered a liability and are valued using the Black-Scholes option-pricing model, the inputs for which include 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. Changes to any of these inputs can have a significant impact to the estimated fair value of the PIPE warrants. As of September 30, 2015, the Company remeasured on a non-recurring basis a portion of its leasehold improvements in its corporate offices using Level III valuation techniques. The write down to fair value of these long-lived assets resulted in an impairment charge of $0.5 million in the year ended December 31, 2015, which was recorded in interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. 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, 2015 Fair Value Level I Level II Level III Assets Money market funds $ 2 $ 2 $ — $ — U.S. government agency obligations 30,352 — 30,352 — Total assets measured at fair value $ 30,354 $ 2 $ 30,352 $ — Liabilities PIPE warrant $ 913 $ — $ — $ 913 Contingent put option 266 — — 266 Total liabilities measured at fair value $ 1,179 $ — $ — $ 1,179 As of December 31, 2014 Fair Value Level I Level II Level III Assets Money market funds $ 33 $ 33 $ — $ — U.S. government agency obligations 15,312 — 15,312 — Total assets measured at fair value $ 15,345 $ 33 $ 15,312 $ — Liabilities PIPE warrant $ 5,577 $ — $ — $ 5,577 Contingent put option 282 — — 282 Total liabilities measured at fair value $ 5,859 $ — $ — $ 5,859 As of December 31, As of December 31, Market Price $3.85 $6.73 Exercise Price $3.40 $3.40 Risk-free interest rate 1.06% 1.10% Expected volatility 80.0% 61.0% Expected life (in years) 1.92 2.92 Expected dividend yield 0.0% 0.0% 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, 2015 and 2014 (in thousands): Year Ended Fair value—beginning of period $ 5,859 Change in fair value of PIPE warrants (2,120 ) Exercise of PIPE warrants (2,544 ) Change in fair value of contingent put option associated with Amended Loan Agreement with Hercules (16 ) Fair value—end of period $ 1,179 Year Ended Fair value—beginning of period $ 13,445 Change in fair value of PIPE warrants (6,988 ) Exercise of PIPE warrants (546 ) Change in fair value of contingent put option associated with 2011 loan and security agreement with Hercules (52 ) Fair value—end of period $ 5,859

Note 3 - Inventories

Note 3 - Inventories	12 Months Ended
	Dec. 31, 2015
Inventory Disclosure [Abstract]
Inventory Disclosure [Text Block]	3. Inventories Inventories consist of finished goods, raw materials and work in process and are stated at the lower of cost or market and consist of the following (in thousands): Balance as of Raw materials $ 140 Work-in-process 181 Finished goods 145 Inventories $ 466

Note 4 - Property and Equipment

Note 4 - Property and Equipment	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment Disclosure [Text Block]	4. Property and Equipment Property and equipment consist of the following (in thousands): As of December 31, 2015 2014 Laboratory equipment $ 3,522 $ 2,549 Leasehold improvements 4,609 4,469 Computer equipment and software 266 334 Construction in process 3,950 4,844 Tooling 1,062 527 Furniture and fixtures 55 50 13,464 12,773 Less accumulated depreciation and amortization (4,854 ) (2,955 ) Property and equipment, net $ 8,610 $ 9,818 Depreciation and amortization expense was $2.0 million, $0.9 million and $0.6 million during the years ended December 31, 2015, 2014 and 2013, respectively. Property and equipment, net in the Consolidated Balance Sheets at December 31, 2015 and 2014, includes $3.0 million and $3.8 million, respectively, related to certain modifications the Company has made at Patheon Pharmaceutical Inc.’s, or Patheon’s, Cincinnati facility under the terms of the Capital Expenditure and Equipment Agreement, or the Capital Agreement.

Note 5 - U.S. Department of Def

Note 5 - U.S. Department of Defense Funding	12 Months Ended
	Dec. 31, 2015
Contractors [Abstract]
Long-term Contracts or Programs Disclosure [Text Block]	5. U.S. Department of Defense Funding In May 2011, AcelRx received a grant from the USAMRMC in which the USAMRMC granted $5.6 million to the Company in order to support the development of investigational product candidate, ARX-04, for the treatment of moderate-to-severe acute pain. Under the terms of the grant, the USAMRMC will reimburse the Company for development, manufacturing and clinical costs necessary to prepare for and complete the planned Phase 2 dose-finding trial in a study of acute moderate-to-severe pain, and to prepare to enter Phase 3 development. The grant gives the USAMRMC the option to extend the term of the grant and provide additional funding for the research. As of December 31, 2013, the full amount of the grant, $5.6 million, had been recognized as revenue. There was no revenue recognized for years ended December 31, 2015 or 2014. Revenue attributable to the research and development performed under the USAMRMC grant, recorded as Contract and other revenue in the Consolidated Statements of Comprehensive Loss, was $2.1 million for the year ended December 31, 2013. On May 11, 2015, the Company entered into a new award contract supported by 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 the Company’s product candidate, ARX-04 (sufentanil sublingual tablet, 30 mcg), a proprietary, non-invasive, single-use tablet in a disposable, pre-filled single-dose applicator, or SDA, for the treatment of moderate-to-severe acute pain, referred to as the DoD Contract. The DoD Contract supports development of ARX-04. Under the terms of the contract, the DoD will reimburse us for costs incurred for development, manufacturing, regulatory and clinical costs outlined in the contract in order to submit an NDA to the FDA, including reimbursement for certain personnel and overhead expenses. The period of performance under the contract began on May 11, 2015. The contract gives the DoD the option to extend the term of the contract and provide additional funding for the research. On March 2, 2016, the DoD Contract was amended to approve enrollment of additional patients in the SAP302 study, approve the addition of the SAP303 study, and extend the contract period of performance by four months from November 10, 2016 to March 9, 2017, to accommodate the increased SAP302 patient enrollment and the SAP303 study. The costs for these changes will be absorbed within the current contract value. If ARX-04 is approved by the FDA, the DoD has the option to purchase a certain number of units of commercial product pursuant to the terms of the contract. Revenue attributable to the work performed under the DoD Contract, recorded as Contract and other revenue in the Consolidated Statements of Comprehensive Loss, was $4.4 million for the year ended December 31, 2015. There was no revenue recognized under the DOD Contract for years ended December 31, 2014 or 2013.

Note 6 - Collaboration Agreemen

Note 6 - Collaboration Agreement	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Collaborative Arrangement Disclosure [Text Block]	6. Collaboration Agreement On December 16, 2013, AcelRx and Grünenthal, entered into a Collaboration and License Agreement, or the License Agreement, and related Manufacture and Supply Agreement, or the MSA, and together with the License Agreement, the Agreements. The License Agreement grants Grünenthal rights to commercialize Zalviso, the Company’s novel sublingual patient-controlled analgesia, or PCA, system, or the Product, in the countries of the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia, or the Territory, for human use in pain treatment within or dispensed by hospitals, hospices, nursing homes and other medically-supervised settings, or the Field. The Company retains rights with respect to the Product in countries outside the Territory, including the United States, Asia and Latin America. 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 entered into amendments to the License Agreement, or the License Amendment, and together with the License Agreement, the Amended License Agreement, and the MSA, or the MSA Amendment, and together with the MSA, the Amended MSA, between the Company and Grünenthal, each effective as of July 17, 2015, and together, the Amended Agreements. In the Amended Agreements, the parties amended the Product supply configurations and packaging of Product components and accessories, and associated pricing therefor, which the Company will manufacture and supply to Grünenthal for the Territory. The parties agreed to increase the pricing of the Product components and accessories in exchange for a reduction of $5.5 million in the total milestone payments due from Grünenthal contingent upon achieving specified net sales targets from a total of $171.5 million to $166.0 million. The parties also updated the development plan for the Product in the Territory, providing for additional near-term development services to be rendered by AcelRx in exchange for payments by Grünenthal of $0.7 million. In accordance with the terms of the Amended MSA, AcelRx also received a binding Product forecast from Grünenthal for approximately $3.7 million. Amended License Agreement Under the terms of the Amended License Agreement, Grünenthal has the exclusive right to commercialize the Product in the Field in the Territory. The Company retains control of clinical development, while Grünenthal and the Company will be responsible for certain development activities pursuant to a development plan as agreed between the parties. The Company will not receive separate payment for such development activities, apart from the $0.7 million included under the Amended Agreements. Grünenthal is exclusively responsible for marketing approval applications and other regulatory filings relating to the sufentanil sublingual tablet drug cartridge for the Product in the Field in the Territory, while the Company is responsible for the CE Mark and other regulatory filings relating to device portions of the Product. In July 2014, Grünenthal submitted an MAA to the European Medicines Agency, or EMA, for Zalviso™ (15 micrograms sufentanil sublingual tablets) for the management of acute moderate-to-severe post-operative pain in adult patients. A CE Mark for Zalviso was obtained in the fourth quarter of 2014 which specifies AcelRx as the device design authority and manufacturer. In September 2015, the European Commission approved the MAA for Zalviso for the 28 European Union member states as well as for the EEA. The Company received an upfront non-refundable cash payment of $30.0 million in December 2013, and a milestone payment of $5.0 million related to the MAA submission in the third quarter of 2014, and an additional $15.0 million milestone payment upon the EC approval of the MAA for Zalviso, which was approved in September 2015. Under the Amended License Agreement, 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 8 “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, the Company will manufacture and supply the Product for use in the Field for the Territory exclusively for Grünenthal. Grünenthal shall purchase from AcelRx, during the first five years after the effective date of the MSA, 100% and thereafter 80% of Grünenthal’s and its sublicensees’ and distributors’ requirements of Product for use in the Field for the Territory. 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. Unless earlier terminated, the Amended MSA continues in effect until the later of the expiration of the obligation of Grünenthal to make royalty and supply and trademark fee payments or the end of any transition period for manufacturing obligations due to the expiration or termination of the Amended License Agreement. The Amended MSA is subject to earlier termination in connection with certain termination events in the Amended License Agreement, in the event the parties mutually agree, by a party in the event of an uncured material breach by the other party or upon the bankruptcy or insolvency of either party. The Company identified the following four significant non-contingent performance deliverables under the original Agreements: 1) intellectual property (license), 2) the obligation to provide research and development services, 3) the significant and incremental discount on the manufacturing of Zalviso for commercial purposes, and 4) the obligation to participate on the joint steering committee. At the time the Amended Agreements were executed, with the exception of the intellectual property license, these obligations remained partially undelivered. Additionally, the Company identified the following three performance deliverables under the License Amendment and the MSA Amendment: 1) the obligation to provide additional research and development services, 2) the obligation to provide Zalviso demonstration device systems, and 3) the obligation to manufacture and deliver Product under the binding forecast. The Company determined that the License Amendment and MSA Amendment are modifications to the original Agreements. The Company considered the provisions of the multiple-element arrangement guidance in determining whether the deliverables outlined above have standalone value and thus should be treated as separate units of accounting. The Company’s management determined that the license under the original License Agreement had standalone value and represented a separate unit of accounting because the rights conveyed permitted Grünenthal to perform all efforts necessary to commercialize and begin selling the product upon regulatory approval. In addition, Grünenthal has the appropriate development, regulatory and commercial expertise with products similar to the product licensed under the agreement and has the ability to engage third parties to manufacture the product allowing Grünenthal to realize the value of the license without receiving any of the remaining deliverables. Grünenthal can also sublicense its license rights to third parties. Also, the Company’s management determined that the research and development services, Zalviso demonstration device systems, joint steering committee participation, the significant and incremental discount on the manufacturing of Zalviso, and the obligation to manufacture and deliver Products each represent individual units of accounting, as Grünenthal could perform such services and/or could acquire these on a separate basis. The Company believes that none of the deliverables have vendor-specific objective evidence, or VSOE, or sufficient third-party evidence, or TPE, of selling price, as none of them have been sold separately by the Company, and as there is only limited information about third party pricing for similar deliverables. Accordingly, the Company developed best estimates of selling prices, or ESP, for each deliverable in order to allocate the noncontingent arrangement consideration to the units of accounting, based on current information available as of the modification date. The Company’s management determined the best estimate of selling price for the license based on Grünenthal’s estimated future cash flows arising from the arrangement. Embedded in the estimate were significant assumptions regarding regulatory expenses, revenue, including potential customer market for the product and product price, costs to manufacture the product and the discount rate. The Company’s management determined the best estimate of selling price of the research and development services and committee participation based on the nature and timing of the services to be performed and in consideration of personnel and other costs incurred in the delivery of the services. For the discount on manufacturing services, the Company’s management estimated the selling price based on the market level of contract manufacturing margin it could have received if it were engaged to supply products to a customer in a separate transaction, the estimated cost of manufacturing, and the anticipated volume of Grünenthal’s orders over the course of the agreement, to which the discount would apply. For the Zalviso demonstration devices and the obligation to manufacture and deliver Product, the Company’s management estimated the selling price based on the binding volume of such devices and Products, the estimated cost of manufacturing, and the market level of contract manufacturing margin. ESP of the license, research and development and committee participation services and the discount on manufacturing services were updated at the time the Amended Agreements were executed for purposes of allocating the amended arrangement consideration. The Amended Agreements entitle the Company to receive additional payments upon the achievement of certain development and sales milestones. Based on ASC Topic 605-28, Revenue Recognition — Milestone Method The substantive milestone payments will be recognized as revenue in their entirety upon the achievement of each substantive milestone. Based on the criteria noted above, the identified substantive milestones in the original Agreements pertain to post approval product enhancements, expanded market opportunities and manufacturing efficiencies for Zalviso. Each of these potential achievements is based primarily on the Company’s performance and involves substantive uncertainty as achievement of these milestones requires future research, development and regulatory activities, which are inherently uncertain in nature. The Company determined that the consideration for each milestone was commensurate with the Company’s performance to achieve the milestone, including future research, development, manufacturing and regulatory activities and that the consideration is reasonable relative to all of the other deliverables and payments within the arrangement. Aggregate potential payments for these milestones total $28.5 million. In addition to substantive milestones, two milestones associated with the original Agreements were deemed not to be substantive. These milestones pertain to regulatory developments for Zalviso in Europe, which the Company’s management deemed to be not substantive due to the high likelihood of achievement, both at inception of the original Agreements and at the time the Amended Agreements were executed. Aggregate potential payments for these milestones totaled $20.0 million. In July 2014, Grünenthal submitted an MAA to the EMA for Zalviso for the management of acute moderate-to-severe post-operative pain in adult patients, triggering the first of these two milestones, a cash payment of $5.0 million. In September of 2015, the MAA was approved by the European Commission, triggering the second of these two milestones, a cash payment of $15.0 million. Amounts received under these non-substantive milestones were allocated to performance deliverables based on the relative selling price method and recognized as appropriate for such deliverables. The Amended Agreements also include milestone payments related to specified net sales targets, totaling $166.0 million. These milestones do not meet the definition of a milestone under ASU 2010-17 because the achievement of these milestones is solely dependent on counter-party performance and not on any performance obligations of the Company. At the time the Amended Agreements were executed, approximately $33.3 million of revenue had been recognized, and $1.7 million remained unrecognized from the aggregate to-date consideration of $35.0 million received under the original Agreements. Upon execution of the Amended Agreements, the Company updated the allocation of this arrangement consideration, along with the consideration owed under the Amended Agreements totaling $54.4 million, consisting of $0.7 million related to research and development services and the demonstration device systems, and $3.7 million related to the Product binding purchase forecast, to all of the identified deliverables in the arrangement (both delivered and undelivered) using their relative selling prices. Further, the $15.0 million non-substantive milestone achieved in September of 2015 was also allocated to the deliverables in the same manner. As a result of such allocations, additional amounts of $13.2 million and $0.5 million were allocated to the previously delivered license and research and development and committee participation services, respectively. A total of $4.4 million was allocated to the significant and incremental discount on manufacturing services, and is expected to be recognized over the period such discount is made available to Grünenthal, beginning in February 2016, on a straight-line basis over the estimated period through 2029. An additional $0.2 million has been allocated to committee participation services and is recognized on a straight-line basis over the performance obligation period extending through 2018. A total of $2.3 million was allocated to manufacturing services for the binding forecast of Products, and is expected to be recognized when the Products are delivered in the first quarter of 2016. The remaining $0.5 million was allocated to the additional research and development services under the Amended License Agreement and demonstration device systems, and manufacturing and delivery of the Products, and will be recognized as those services are performed or as the devices are delivered, as applicable. Below is a summary of revenue recognized under the Amended Agreements during the years ended December 30, 2015, 2014 and 2013 (in thousands): Years Ended December 31, 2015 2014 2013 License $ 13,167 $ 4,560 $ 27,370 Joint steering committee, research and development services and demonstration devices 1,690 657 — Total $ 14,857 $ 5,217 $ 27,370 As of December 31, 2015, the Company had current and noncurrent portions of the deferred revenue balance under the Amended Agreements of $2.6 million and $0.6 million, respectively.

Note 7 - Long-term Debt

Note 7 - Long-term Debt	12 Months Ended
	Dec. 31, 2015
Disclosure Text Block [Abstract]
Long-term Debt [Text Block]	7. Long-Term Debt Hercules Loan and Security Agreements In June 2011, AcelRx entered into the Loan and Security Agreement, or the Loan Agreement, between the Company and with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., together, the Lenders, under which AcelRx borrowed $20.0 million in two tranches of $10.0 million each, represented by secured convertible term promissory notes. The Company borrowed the first tranche of $10.0 million upon the closing of the transaction on June 29, 2011 and borrowed the second tranche of $10.0 million in December 2011. The Company used a portion of the proceeds from the first tranche to repay the remaining obligations under that certain loan and security agreement between the Company and Pinnacle Ventures, L.L.C., or Pinnacle Ventures, dated September 16, 2008. The interest rate for each tranche was 8.50%. In connection with the loan, the Company issued Hercules seven-year warrants to purchase an aggregate of 274,508 shares of common stock at a price of $3.06 per share. See Note 9 “Warrants” for further description. On December 16, 2013, AcelRx entered into an Amended and Restated Loan and Security Agreement with the Lenders, or the Amended Loan Agreement, under which the Company may borrow up to $40.0 million in three tranches. The loans are represented by secured convertible term promissory notes, collectively, the Notes. The Amended Loan Agreement amends and restates the Loan Agreement between the Company and the Lenders dated as of June 29, 2011. The Company borrowed the first tranche of $15.0 million upon closing of the transaction on December 16, 2013, and the second tranche of $10.0 million on June 16, 2014 . The Company used approximately $8.6 million of the proceeds from the first tranche to repay its obligations under the Loan and Security Agreement with the Lenders. The Company recorded the new debt at an estimated fair value of $24.9 million as of December 31, 2014. In accordance with ASC Topic No. 470, “Debt – Modifications and Extinguishments” (Topic No. 470), the amendment noted above was determined to be an extinguishment of the existing debt and an issuance of new debt. The Company reached this conclusion based on a comparison of discounted remaining cash flows of the original loan agreement compared to the amended loan agreement, the result of which was a greater than 10% difference in discounted cash flows. The Company determined this difference to be significant and recorded the new debt at estimated fair value. As a result of the extinguishment, the Company recorded a $1.2 million loss on extinguishment of debt which was recorded as interest income and other income (expense), net on the Consolidated Statements of Comprehensive Loss during the year ended December 31, 2013. The loss on extinguishment was a non-cash write off, consisting of deferred debt charges, the unamortized portion of the original issue discount related to the Loan Agreement and other fees associated with extinguishing the debt, including the estimated fair value of warrants issued in connection with the Amended Loan Agreement, facility and legal fees associated with the Amended Loan Agreement and the value of the contingent put option liability associated with the Loan Agreement at the time of the amendment. On September 24, 2014, the Company entered into Amendment No. 1 to the Amended Loan Agreement with Hercules. Amendment No. 1 extended the time period under which the Company could draw down the third tranche, of up to $15.0 million, from March 15, 2015 to August 1, 2015, subject to the Company obtaining approval for Zalviso from the FDA. The Company did not receive FDA approval of Zalviso by August 1, 2015 and as such, will not have access to the third tranche. On September 18, 2015, concurrently with the closing of the Royalty Monetization, the Company entered into a Consent and Amendment No. 2, or Amendment No. 2, to the Amended Loan Agreement with the Lenders. Amendment No. 2 includes an interest only period from October 1, 2015 through March 31, 2016, with the potential for further extension to September 30, 2016 upon satisfaction of certain conditions , which have since been satisfied. Loans under the Amended Loan Agreement mature on October 31, 2017. In connection with Amendment No. 2, the Company reduced the exercise price of the warrants already held by the Lenders, which are exercisable for an aggregate of 176,730 shares of Common Stock, from the previous exercise price of $6.79 per share to $3.88 per share, or the Warrant Amendments. See Note 9 “Warrants” for further description. The interest rate for each tranche will be calculated at a rate equal to the greater of either (i) 9.10% plus the prime rate as reported from time to time in The Wall Street Journal minus 5.25%, and (ii) 9.10%. Payments under the Amended Loan Agreement were interest only until April 1, 2015, followed by equal monthly payments of principal and interest through September 30, 2015, to be followed by an interest only period from October 1, 2015 through September 30, 2016, and by equal monthly payments of principal and interest from October 1, 2016 through the scheduled maturity date on October 1, 2017, or the Loan Maturity Date. In addition, a final payment equal to $1.7 million will be due on the Loan Maturity Date, or such earlier date specified in the Amended Loan Agreement. The Company’s obligations under the Amended Loan Agreement are secured by a security interest in substantially all of its assets, other than its intellectual property and those assets sold under the Royalty Monetization. If the Company prepays the Amended Loan Agreement prior to maturity, it will pay Hercules a prepayment charge based on a percentage of the then outstanding principal balance, or 1% if the prepayment occurs after December 16, 2015. Subject to certain conditions and limitations set forth in the Amended Loan Agreement, the Company has the right to convert up to $5.0 million of scheduled principal installments under the Notes into freely tradeable shares of the Company’s common stock, or Common Stock. The number of shares of Common Stock that would be issued upon conversion of the Amended Notes would be equal to the number determined by dividing (x) the product of (A) the principal amount to be paid in shares of Common Stock and (B) 103%, by (y) $9.30 (subject to certain proportional adjustments as provided for in the Amended Loan Agreement). The Amended Loan Agreement includes customary affirmative and restrictive covenants, but does not include any financial maintenance covenants, and 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 Hercules’ security interest or in the value of the collateral, and events relating to bankruptcy or insolvency. Upon the occurrence of an event of default, a default interest rate of an additional 5% may be applied to the outstanding loan balances, and Hercules may declare all outstanding obligations immediately due and payable and take such other actions as set forth in the Amended Loan Agreement. Upon an event of default, including a change of control, Hercules has the option to accelerate repayment of the Amended Loan Agreement, including payment of any applicable prepayment charges, which range from 1%-3% of the outstanding loan balance and accrued interest, as well as a final payment fee of $1.7 million. This option is considered a contingent put option liability, as the holder of the loan may 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 the Amended Loan Agreement entered into on December 16, 2013 was considered an extinguishment, the contingent put option liability associated with the Loan Agreement, which had an estimated fair value of $32,000 at the time of the amendment, was written off as a part of the loss on extinguishment, and a new contingent put option liability was established. As of December 31, 2015 and 2014, the estimated fair value of the contingent put option liability was $266,000 and $282,000, respectively, 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. The resulting difference between the two estimated fair values is the estimated fair value of the default provisions, or the contingent put option. 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 contingent put option liability was recorded as a debt discount to the loan and consequently a reduction to the carrying value of the loan. The contingent put option liability is revalued at the end of each reporting period and any change in the fair value is recognized in interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. The Company performed an analysis of Amendment No. 2 to determine if it was a modification or extinguishment of the debt under the Amended Loan Agreement. The Company assumed immediate prepayment of both the pre-modification debt and post-modification debt, including the change in the fair value due to the Warrant Amendments, and concluded that Amendment No. 2 was a modification rather than an extinguishment of the debt. The principal balance due under the Amended Loan Agreement was $20.9 million at December 31, 2015, and $24.9 million at December 31, 2014. Interest expense related to the Amended Loan Agreement was $3.0 million, $0.8 million of which represented amortization of the debt discount, for the year ended December 31, 2015, and $2.6 million, $0.5 million of which represented amortization of the debt discount, for the year ended December 31, 2014. Amortization of the debt discount prior to amending the Hercules loan and security agreement in December 2013, which was recorded as interest expense, was $0.4 million for the year ended December 31, 2013. Future Payments on Long-Term Debt The following table summarizes our outstanding future payments associated with the Company’s long-term debt as of December 31, 2015 (in thousands): 2016 $ 6,400 2017 18,305 Total payments 24,705 Less amount representing interest (2,539 ) Notes payable, gross 22,166 Unamortized portion of final payment (1,224 ) Unamortized discount on notes payable (20 ) 20,922 Less current portion of notes payable, including unamortized discount 4,541 Notes payable, less current portion $ 16,381

Note 8 - Liability Related to S

Note 8 - Liability Related to Sale of Future Royalties	12 Months Ended
	Dec. 31, 2015
Liability Related To Sale Of Future Royalties Disclosure [Abstract]
Liability Related To Sale Of Future Royalties Disclosure [Text Block]	8. Liability Related to Sale of Future Royalties On September 18, 2015, the Company consummated the Royalty Monetization, in which it sold certain royalty and milestone payment rights to its newly formed wholly owned subsidiary, ARPI LLC, pursuant to a Purchase and Sale Agreement, or PSA. Subsequently, ARPI LLC sold the royalty and milestone payment rights to PDL for an upfront cash purchase price of $65.0 million, subject to a capped amount of $195.0 million pursuant to the Subsequent Purchase and Sale Agreement, or SPSA. Under the SPSA, PDL 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% of $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 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 PDL and payments the Company is required to make to PDL, up to a capped amount of $195.0 million, over the life of the arrangement. The sum of the capped amount of $195.0 million, 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. The Company’s estimate of the interest rate under the arrangement is based on the amount of royalty and milestone payments expected to be received by PDL over the life of the arrangement. The Company’s estimate of this total interest expense resulted in an effective annual interest rate of approximately 14%. The Company will periodically assess 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 our initial estimates or the timing of such payments is materially different than our original estimates, the Company will prospectively adjust the amortization of the liability and the interest rate. The following table shows the activity within the liability account during the year ended December 31, 2015 (in thousands): Liability related to sale of future royalties—beginning balance (as of December 31, 2014) $ — Net proceeds from sale of future royalties 61,184 Non-cash interest expense recognized 2,428 Payments from AcelRx to PDL — Total liability related to sale of future royalties as of December 31, 2015 63,612 Less: current portion 118 Liability related to sale of future royalties, less current portion $ 63,494 As royalties are remitted to PDL from ARPI LLC, as described in Note 1 “Organization and Summary of Significant Accounting Policies,” the balance of the liability will be effectively repaid over the life of the agreement. The Company will record non-cash royalty revenues and non-cash interest expense within its Consolidated Statements of Comprehensive Loss over the term of the Royalty Monetization.

Note 9 - Warrants

Note 9 - Warrants	12 Months Ended
	Dec. 31, 2015
Warrants Disclosure [Abstract]
Warrants Disclosure [Text Block]	9. Warrants Series A Warrants As of December 31, 2015, warrants to purchase 3,425 shares of common stock had not been exercised and were still outstanding. These warrants expire in March 2017. Pinnacle Warrants In February 2013, warrants to purchase 228,264 shares were net exercised, for 58,580 shares of common stock. As of December 31, 2015, no warrants to purchase shares of common stock issued to Pinnacle were outstanding. Hercules Warrants In connection with the Amended Loan Agreement, executed in December 2013, the Company issued warrants to Hercules 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 Amended 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 Warrant Amendments. Each Warrant 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 five 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 $1.1 million, which was used in the estimating the fair value of the amended 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 original strike price of $6.79, the stock price at issuance of $9.67, the five-year contractual term of the warrants, a risk-free interest rate of 1.55%, expected volatility of 71% and 0% expected dividend yield. The Company estimated the fair value of the modification of the Warrants, or the Warrant Amendments, as of the issuance date to be $0.1 million, which was used in estimating the fair value of the amended debt instrument and was recorded as equity. As of December 31, 2015, warrants to purchase 176,730 shares of common stock issued to Hercules had not been exercised and were still outstanding. These warrants expire in December 2018. In connection with the Loan Agreement with Hercules, executed in June 2011, the Company issued to Hercules warrants to purchase an aggregate of 274,508 shares of common stock at a price of $3.06 per share, which were net exercised for 183,404 shares of common stock during the year ended December 31, 2013. 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, as determined by the Black-Scholes option-pricing model, 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 Black-Scholes assumptions used to value the PIPE warrants are disclosed in Note 2 “Investments and Fair Value Measurement.” 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. As of December 31, 2015, the fair value of the PIPE warrants was estimated to be $0.9 million. The change in fair value for the years ended December 31, 2015, and 2014, which was recorded as other income, was $2.1 million, and $7.0 million, respectively. The change in fair value for the year ended December 31, 2013, which was recorded as other expense, was $14.1 million. During the year ended December 31, 2015, PIPE warrants to purchase 847,058 shares were net exercised for 527,101 shares of common stock. During the year ended December 31, 2014, PIPE warrants to purchase 135,000 shares were net exercised for 91,488 shares of common stock. During the year ended December 31, 2013, warrants to purchase 1,135,589 shares were net exercised, for 808,078 shares of common stock. As of December 31, 2015, PIPE warrants to purchase 512,456 shares of common stock issued in connection with the Private Placement had not been exercised and were outstanding. These warrants expire in November 2017.

Note 10 - Commitments and Conti

Note 10 - Commitments and Contingencies	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies Disclosure [Text Block]	10. Commitments and Contingencies Operating Leases In December 2011, the Company entered into a non-cancelable lease agreement for approximately 13,787 square feet of office and laboratory facilities in Redwood City, California, which serve as the Company headquarters, effective April 2012. The lease agreement expires in May 2016. Rent expense from the facility lease is recognized on a straight-line basis from the inception of the lease in December 2011, the early access date, through the end of the lease. In May 2014, the Company entered into an amendment, or the Lease Amendment, to that certain lease dated December 21, 2011, with Metropolitan Life Insurance Company, or the Existing Lease, for 13,787 square feet of space located at 301 Galveston Drive, Redwood City, California, or the Current Premises. Pursuant to the Lease Amendment, the term of the Existing Lease has been extended for a period of twenty (20) months and twenty-two (22) days and expiring January 31, 2018, or the Expiration Date, unless sooner terminated pursuant to the terms of the Existing Lease. In addition, the Lease Amendment included a new lease on an additional 12,106 square feet of office space, or the Expansion Space, which is adjacent to the current premises. The new lease for the Expansion Space has a term of 42 months commencing on August 1, 2014, and expiring on the Expiration Date. The Company has an option to extend the term of the Lease Amendment for an additional five years, which would commence upon the Expiration Date, at a market rate determined according to the Existing Lease. On October 2, 2015, the Company executed an agreement to sublease 11,871 sq. of its Expansion Space located at 301 Galveston Drive, Redwood City, California for a term of 26 months commencing on December 1, 2015. The sublessee is entitled to abatement of the first two monthly installments of rent. Subsequent monthly installments of rent start at a rental rate of $2.05 per square foot (subject to agreed nominal increases). Upon the completion of the sublease, the Company has the option to take back the subleased space. Minimum rents expected to be received under this sublease are $0.3 million, $0.3 million and $0.0 million for the years ending December 31, 2016, 2017 and 2018, respectively. Rent expense was $0.6 million, $0.5 million and $0.3 million during the years ended December 31, 2015, 2014 and 2013, respectively. Future minimum payments under the lease agreement as of December 31, 2015, are as follows (in thousands): Year Ending December 31: 2016 $ 717 2017 737 2018 62 Total minimum payments $ 1,516 In addition, the Company will pay the Landlord specified percentages of certain operating expenses and taxes related to the leased facility incurred by the Landlord. Litigation On October 1, 2014, a securities class action complaint was filed in the U.S. District Court for the Northern District of California against AcelRx and certain of its current and former officers. On April 17, 2015, lead plaintiff filed an amended complaint. The amended complaint alleged that between September 30, 2013 and July 25, 2014, AcelRx and certain of its current and former officers violated Sections 10(b) and 20(a) of the Securities Exchange Act of 1934 in connection with statements related to our lead drug candidate, Zalviso. On November 25, 2015, the Court granted the Company’s Motion to Dismiss. Plaintiffs had the opportunity to file an amended complaint within 30 days’ which they declined to do. On January 18, 2016, the Court issued an order dismissing the case with prejudice. From time to time the Company may be involved in additional 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

Note 11 - Stockholders' Equity	12 Months Ended
	Dec. 31, 2015
Stockholders' Equity Note [Abstract]
Stockholders' Equity Note Disclosure [Text Block]	11. Stockholders’ Equity Common Stock Public Offerings On July 23, 2013, AcelRx completed an underwritten public offering of 4,370,000 shares of common stock, at a price of $11.65 per share to the public. The total gross proceeds of this offering were $50.9 million with net proceeds to AcelRx of $47.9 million after deducting underwriting discounts and commissions and other expenses payable by AcelRx. Private Placement Offering On June 1, 2012, or the Issuance Date, the Company issued an aggregate of 2,922,337 shares of common stock and warrants to purchase up to 2,630,103 shares of common stock, or the PIPE warrants, for aggregate gross proceeds of $10.0 million, or the Private Placement. Costs related to the offering were $0.9 million. The shares of common stock and PIPE warrants issued in the Private Placement were sold pursuant to a Securities Purchase Agreement, or Purchase Agreement, dated May 29, 2012, between the Company and certain purchasers, including certain entities affiliated with Mark Wan and Stephen J. Hoffman, members of the Company’s board of directors. Pursuant to the Purchase Agreement, AcelRx sold shares of common stock and PIPE warrants to purchase common stock in immediately separable “Units,” with each Unit consisting of (i) one share of common stock and (ii) a PIPE warrant to purchase 0.9 of a share of common stock. The per share exercise price of the PIPE warrants was $3.40. The offering price per Unit was $3.40 for non-affiliated investors, and $3.5125 for affiliated investors, which equals the sum of (i) $3.40, the closing consolidated bid price of the Company’s common stock on May 29, 2012, plus (ii) $0.1125 (which is equal to $0.125 per PIPE warrant share, multiplied by 0.9), for an aggregate amount of $10.0 million. 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. In connection with the Private Placement, the Company filed a registration statement with the U.S. Securities and Exchange Commission, or SEC, registering for resale the shares of common stock and shares of common stock issuable upon exercise of the warrants sold in the Private Placement. The registration statement was declared effective by the SEC in July 2012. Stock Plans 2006 Stock Plan In August 2006, the Company established the 2006 Plan in which 342,000 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 375,000 shares of common stock were reserved for issuance under the 2006 Plan and, in November 2009, an additional 1,376,059 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 a successor to the 2006 Plan. The 2011 Incentive Plan became effective immediately upon the execution and delivery of the underwriting agreement for the IPO on February 10, 2011. 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 51,693 shares reserved under the 2006 Plan that remained available for future grant at the time of the IPO were transferred to the share reserve of the 2011 Incentive Plan. The initial aggregate number of shares of the Company’s common stock that may be issued pursuant to stock awards under the 2011 Incentive Plan is 1,875,000 shares, which number was the sum of (i) 51,693 shares remaining available for future grant under the 2006 Plan at the time of the execution and delivery of the underwriting agreement for the Company’s IPO, and (ii) an additional 1,823,307 new shares. Then, the number of shares of common stock reserved for issuance under the 2011 Incentive Plan will automatically increase on January 1st 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 the option 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 share-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, which also became effective immediately upon the execution and delivery of the underwriting agreement for the IPO. Initially, 250,000 shares of the Company’s common stock were authorized for issuance under the ESPP pursuant to purchase rights granted to the Company’s employees or to employees of any of its designated affiliates. The number of shares of the Company’s common stock reserved for issuance will automatically increase on January 1st 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. As of December 31, 2015, 350,148 shares have been issued to employees and there are 291,207 shares available for issuance under the ESPP. The weighted average fair value of shares issued under the ESPP in 2015, 2014 and 2013 was $4.48, $4.35 and $3.97 per share, respectively. In January 2016, an additional 904,953 shares were authorized for issuance under the 2011 Employee Stock Purchase Plan.

Note 12 - Stock-based Compensat

Note 12 - Stock-based Compensation	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Disclosure of Compensation Related Costs, Share-based Payments [Text Block]	12. Stock-Based Compensation The Company recorded total stock-based compensation expense for stock options, stock awards and the ESPP as follows December 31, December 31, December 31, Cost of goods sold $ 67 $ — $ — Research and development 2,587 2,252 1,657 General and administrative 2,356 2,188 1,822 Total $ 5,010 $ 4,440 $ 3,479 The following table summarizes option activity under the 2011 Plan and 2006 Plan: Number Weighted- Weighted- Aggregate (in thousands) December 31, 2014 6,366,763 $ 5.74 Granted 560,500 4.28 Forfeited (997,099 ) 7.22 Expired (372,718 ) 6.19 Exercised (938,497 ) 2.95 December 31, 2015 4,618,949 $ 5.77 7.3 $ 1,079 Vested and exercisable options—December 31, 2015 2,919,289 $ 5.14 6.5 $ 1,036 Vested and expected to vest—December 31, 2015 4,523,784 $ 5.75 7.2 $ 1,076 As of December 31, 2015, there were 2,654,302 shares available for future grant under the 2011 Plan. In January 2016, an additional 1,809,906 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, 2015 is summarized below: Options Outstanding Options Vested and Exercisable Exercise Prices Number of Weighted-Average Weighted-Average Shares Subject Weighted-Average $ 1.20 - $2.56 463,444 4.1 $ 2.33 463,444 $ 2.33 $ 3.11 - $4.73 1,396,208 7.0 $ 3.67 1,033,204 $ 3.56 $ 5.31 - $8.18 1,820,297 7.7 $ 5.92 948,650 $ 5.64 $ 10.22 - $10.55 939,000 8.3 $ 10.33 473,991 $ 10.35 4,618,949 7.3 $ 5.77 2,919,289 $ 5.14 The weighted average grant-date fair value of options granted during the years ended December 31, 2015, 2014 and 2013 was $2.69, $5.57 and $4.15 per share, respectively. As of December 31, 2015, total stock-based compensation expense related to unvested options to be recognized in future periods was $7.3 million which is expected to be recognized over a weighted-average period of 2.3 years. The grant date fair value of shares vested during the years ended December 31, 2015, 2014 and 2013 was $5.4 million, $3.2 million and $1.9 million, respectively. The total intrinsic value of options exercised during the years ended December 31, 2015, 2014 and 2013 was $1.3 million, $2.3 million and $3.6 million, respectively. The Company used the following assumptions to calculate the fair value of each employee stock option: Year Ended December 31, 2015 2014 2013 Expected term (in years) 5.25 - 6.25 5.25 - 6.25 5.75 - 6.25 Risk-free interest rate 1.35% - 1.82% 1.76% - 1.92% 1.02% - 2.96% Expected volatility 72% 69 - 72% 80% Expected dividend rate 0% 0% 0% Restricted Stock Units In March 2011, the Company granted 343,815 Restricted Stock Units, or RSUs, to employees and directors under the 2011 Plan at a grant date fair value of $3.45. The fair value of the RSUs was determined on the date of grant based on the market price of the Company’s common stock. RSUs are recognized as expense ratably over the vesting period and the Company’s RSU’s generally vest over three years as follows: 25% on the 6 month anniversary of the vesting commencement date, 25% on the 12 month anniversary of the vesting commencement date, 25% on the 24 month anniversary of the vesting commencement date and 25% on the 36 month anniversary of the vesting commencement date, so long as the RSU recipient continues to provide services to the Company. As of December 31, 2015 and 2014, there were no RSUs outstanding. The expense related to RSUs during the years ended December 31, 2015, 2014 and 2013 was $0, $56,000 and $290,000, respectively.

Note 13 - Restructuring Costs

Note 13 - Restructuring Costs	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Related Activities Disclosure [Text Block]	13. Restructuring Costs On March 19, 2015, the Board of Directors of the Company, in connection with its efforts to reduce operating costs, conserve capital, focus the Company's financial and development resources on working with the FDA to seek marketing approval for Zalviso, and continuing development of ARX-04, implemented a cost reduction plan. The cost reduction plan reduced the Company’s workforce by 19 employees, approximately 36% of total headcount, in the first quarter of 2015. Employee termination benefits related to this restructuring, are charged to restructuring costs in the Consolidated Statements of Comprehensive Loss. The Company recorded restructuring costs as follows (in thousands): December 31, 2015 Employee termination benefits $ 756 Total restructuring costs $ 756 The following table presents activities related to the cost reduction plan for the year ended December 31, 2015 (in thousands): Employee severance and related costs Balance of restructuring liability at December 31, 2014 $ — Charges 756 Payments (756 ) Balance of restructuring liability at December 31, 2015 $ — The restructuring liability has been fully disbursed as of December 31, 2015.

Note 14 - Net Loss per Share of

Note 14 - Net Loss per Share of Common Stock	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Earnings Per Share [Text Block]	14. 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 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. During the years ended December 31, 2015 and 2014, the PIPE warrants had a dilutive impact to net loss per share due to a lower share price at December 31, 2015 and 2014, compared to the closing share price on December 31, 2014 and 2013, respectively. The decrease in share price created a lower Black-Scholes value and lower liability for the PIPE warrants, which resulted in other income during the years ended December 31, 2015 and 2014. The calculation of diluted net loss per share requires that, to the extent the average market price of the underlying shares for the reporting period exceeds the exercise price of the PIPE warrants and the presumed exercise of such securities are dilutive to loss per share for the period, adjustments to net loss used in the calculation are required to remove the change in fair value of the PIPE warrants for the period. Likewise, adjustments to the denominator are required to reflect the related dilutive shares. The following table is a reconciliation of the numerators and denominators used in the calculation of basic and diluted net loss per share computations for the years ended December 31, 2015, 2014 and 2013: Years Ended December 31, 2015 2014 2013 (in thousands, except share and per share amounts) Numerator: Net loss used to compute net loss per share Basic $ (24,399 ) $ (33,353 ) $ (23,426 ) Adjustments for change in fair value of warrant liability (2,120 ) (6,988 ) — Diluted $ (26,519 ) $ (40,341 ) $ (23,426 ) Denominator: Weighted average shares outstanding used to compute net loss per share: Basic 44,300,099 43,427,111 39,746,678 Dilutive effect of warrants 168,341 895,186 — Diluted 44,468,440 44,322,297 39,746,678 Net loss per share—basic $ (0.55 ) $ (0.77 ) $ (0.59 ) Net loss per share—diluted $ (0.60 ) $ (0.91 ) $ (0.59 ) 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, 2015 2014 2013 ESPP and stock options to purchase common stock 4,699,121 6,411,003 4,988,459 Restricted Stock Units — — 65,765 Convertible debt into common stock 553,763 553,763 553,763 Common stock warrants 180,155 180,155 1,674,669

Note 15 - Accrued Liabilities

Note 15 - Accrued Liabilities	12 Months Ended
	Dec. 31, 2015
Payables and Accruals [Abstract]
Accounts Payable and Accrued Liabilities Disclosure [Text Block]	15. Accrued Liabilities Accrued liabilities consist of the following (in thousands): December 31, 2015 2014 Accrued compensation and employee benefits $ 2,876 $ 2,540 Accrued liabilities associated with Grünenthal collaboration — 499 Inventory and other contract manufacturing accruals 272 — Other accrued liabilities 808 615 Total accrued liabilities $ 3,956 $ 3,654

Note 16 - 401(k) Plan

Note 16 - 401(k) Plan	12 Months Ended
	Dec. 31, 2015
Compensation and Retirement Disclosure [Abstract]
Pension and Other Postretirement Benefits Disclosure [Text Block]	16. 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 $263,000, $201,000 and $143,000 for the years ended December 31, 2015, 2014 and 2013, respectively.

Note 17 - Related Party Transac

Note 17 - Related Party Transactions	12 Months Ended
	Dec. 31, 2015
Related Party Transactions [Abstract]
Related Party Transactions Disclosure [Text Block]	17. Related Party Transactions Stephen Hoffman is a Senior Advisor to PDL and a member of the Company's Board of Directors, or the Board. The Board was aware of Dr. Hoffman’s status as an interested party in the Royalty Monetization and Dr. Hoffman recused himself from all deliberations and actions taken by the Board with respect to the Royalty Monetization. Dr. Hoffman’s consulting compensation from PDL is composed, in part, of a success fee which is formula driven based on a minimum dollar value of deals and the total dollar value of the deals, his relative contribution to each of the concluded deals and the total dollar value deployed in 2015. PDL estimates the amount attributable to the AcelRx transaction to be approximately $260,000.

Note 18 - Income Taxes

Note 18 - Income Taxes	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Income Tax Disclosure [Text Block]	18. Income Taxes The Company did record a provision for income taxes of $0.8 million during the year ended December 31, 2015. The Company did not record a provision for income taxes during the years ended December 31, 2014 and 2013. Net deferred tax assets as of December 31, 2015 and 2014 consist of the following (in thousands): December 31, December 31, Deferred tax assets: Accruals and other $ 3,162 $ 4,446 Research credits 5,105 4,413 Net operating loss carryforward 30,294 42,330 Section 59(e) R&D expenditures 12,785 17,083 Deferred revenue 21,677 — AMT credit 742 — Total deferred tax assets 73,765 68,272 Valuation allowance (73,765 ) (68,272 ) Net deferred tax assets $ — $ — Reconciliations of the statutory federal income tax to the Company’s effective tax during the years ended December 31, 2015, 2014 and 2013 are as follows (in thousands): Year Ended December 31, 2015 2014 2013 Tax at statutory federal rate $ (8,037 ) $ (11,392 ) $ (7,965 ) State tax—net of federal benefit 2,853 (2,501 ) (716 ) PIPE Warrant liability (726 ) (2,393 ) 4,898 General Business credits (455 ) (628 ) (1,326 ) Stock Options 1,559 543 Other 73 20 (80 ) Change in valuation allowance 5,493 16,351 5,189 Provision for income taxes $ 760 $ — $ — 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 $5.5 million, $16.4 million, and $4.8 million during the years ended December 31, 2015, 2014 and 2013, respectively. As of December 31, 2015, the Company had federal net operating loss carryforwards of $73.8 million, which begin to expire in 2029. As of December 31, 2015, the Company had state net operating loss carryforwards of $108.9 million, which begin to expire in 2016. As of December 31, 2015, approximately $2.9 million of federal and $2.8 million of state net operating loss is attributable to stock-based compensation deductions in excess of book expense. When realized, the benefit of the tax deduction related to these options will be accounted for as a credit to stockholders’ equity rather than as a reduction of the income tax provision. As of December 31, 2015, the Company had a federal alternative minimum tax credit carryover of $0.7 million. As of December 31, 2015, the Company had federal research credit carryovers of $5.0 million, which begin to expire in 2026. As of December 31, 2015, the Company had state research credit carryovers of $2.8 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, $26,000 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, 2015, 2014 and 2013 is as follows (in thousands): Year Ended December 31, 2015 2014 2013 Unrecognized benefit—beginning of period $ 1,667 $ 1,341 $ 810 Gross decreases—prior period tax positions — — 221 Gross increases—current period tax positions 272 326 310 Unrecognized benefit—end of period $ 1,939 $ 1,667 $ 1,341 The entire amount of the unrecognized tax benefits would not impact the Company’s effective tax rate if recognized. Accrued interest and penalties related to unrecognized tax benefits are classified as income tax expense and were immaterial. The Company files income tax returns in the United States and in California. The tax years 2005 through 2015 remain open in both jurisdictions. The Company is not currently under examination by income tax authorities in federal, state or other foreign jurisdictions. The Company does not anticipate any significant changes within 12 months of this reporting date of its uncertain tax positions.

Note 19 - Subsequent Events

Note 19 - Subsequent Events	12 Months Ended
	Dec. 31, 2015
Subsequent Events [Abstract]
Subsequent Events [Text Block]	1 9 . Subsequent Events On March 2, 2016, the Company entered into an amendment to the award contract with the DoD in which the DoD agreed to approve enrollment of additional patients in the SAP302 study, approve the addition of the SAP303 study, and extend the contract period of performance by four months from November 10, 2016 to March 9, 2017, to accommodate the increased SAP302 patient enrollment and the SAP303 study. The costs for these changes will be absorbed within the current contract value. All other terms and conditions remain unchanged.

Note 20 - Unaudited Quarterly F

Note 20 - Unaudited Quarterly Financial Data	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Quarterly Financial Information [Text Block]	20. Unaudited Quarterly Financial Data The following table sets forth certain unaudited quarterly financial data for the eight quarters ended December 31, 2015. 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. 2015 2014 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Revenues $ 181 $ 1,924 $ 15,428 $ 1,730 $ 95 $ 71 $ 4,825 $ 226 Operating costs and expenses $ 11,581 $ 10,047 $ 8,323 $ 9,266 $ 8,636 $ 12,331 $ 9,894 $ 12,005 Net income / (loss) $ (10,026 ) $ (8,896 ) $ 5,069 $ (10,546 ) $ (9,631 ) $ (10,575 ) $ 671 $ (13,818 ) Net income / (loss) per share (basic) $ (0.23 ) $ (0.20 ) $ 0.11 $ (0.24 ) $ (0.22 ) $ (0.24 ) $ 0.02 $ (0.32 ) Net income / (loss) per share (diluted) $ (0.27 ) $ (0.20 ) $ 0.11 $ (0.24 ) $ (0.22 ) $ (0.30 ) $ (0.13 ) $ (0.32 )

Accounting Policies, by Policy

Accounting Policies, by Policy (Policies)	12 Months Ended
	Dec. 31, 2015
Accounting Policies [Abstract]
The Company [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 the treatment of acute pain. AcelRx intends to commercialize its product candidates in the United States and license the development and commercialization rights to its product candidates for sale outside of the United States through strategic partnerships and collaborations. AcelRx may also consider the option to enter into strategic partnerships for its product candidates in the United States. In September 2015, the Company reported that SAP301, a pivotal Phase 3 study for ARX-04 (sufentanil sublingual tablet, 30 mcg), a proprietary, non-invasive, single-use tablet in a disposable, pre-filled single-dose applicator, or SDA, for the treatment of moderate-to-severe acute pain, met primary and secondary endpoints in a multi-center, double-blind, placebo-controlled trial designed to study the short-term treatment of patients with moderate-to-severe acute pain following ambulatory abdominal surgery. In October 2015, we announced the initiation of SAP302, an open-label Phase 3 study of ARX-04 for the treatment of adult patients who present in the emergency room with moderate-to-severe acute pain associated with trauma or injury. The SAP302 study is expected to be completed by the third quarter of 2016. The Company has initiated SAP303, an open-label, single-arm study of ARX-04 in post-operative patients over 40 years of age that will allow for administration of ARX-04 for up to 12 hours. This study is also expected to be completed by the third quarter of 2016. The Company believes ARX-04 may be a candidate for use in a variety of medically supervised settings to manage moderate-to-severe acute pain, including emergency room patients; patients who are recovering from short-stay or ambulatory surgery and do not require more long-term patient-controlled analgesia; post-operative patients who are transitioning from the operating room to the recovery floor; patients being transported by paramedics; and battlefield casualties. The Company’s other late-stage investigational product candidate, Zalviso™, delivers 15 mcg sufentanil sublingually through a non-invasive delivery route via a pre-programmed, patient-controlled analgesia device. In response to the New Drug Application, or NDA, the Company submitted to the U.S. Food and Drug Administration, or FDA, seeking approval for Zalviso, the Company received a Complete Response Letter, or CRL, on July 25, 2014. The FDA has requested an additional clinical study and the Company is planning to begin this study, IAP312, in the first quarter of 2016. On December 16, 2013, AcelRx and Grünenthal GmbH, or Grünenthal, entered into a Collaboration and License Agreement, or the License Agreement, which was amended effective July 17, 2015, or the Amended License Agreement, which grants Grünenthal rights to commercialize Zalviso in the countries of the European Union, Switzerland, Liechtenstein, Iceland, Norway and Australia. In September 2015, the European Commission approved the Marketing Authorization Application, or MAA, previously submitted to the European Medicines Agency, or EMA, for Zalviso for the management of acute moderate-to-severe post-operative pain in adult patients. The approval allows Grünenthal to market Zalviso in the 28 European Union member states as well as for the European Economic Area countries, Norway, Iceland and Liechtenstein, or EEA. Also on December 16, 2013, AcelRx and Grünenthal, entered into a related 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 entered into an amendment to the MSA, or the MSA Amendment, and together with the MSA, the Amended MSA, between the Company and Grünenthal, each effective as of July 17, 2015, and together, with the Amended License Agreement, the Amended Agreements. The Company has incurred recurring operating losses and negative cash flows from operating activities since inception and expects to continue to incur negative cash flows. Although Zalviso has been approved for sale in the European Union, 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. As a result, the Company expects to continue to incur negative cash flows. When we refer to "we," "our," "us," the "Company" or "AcelRx" in this document, we mean the current Delaware corporation, or AcelRx Pharmaceuticals, Inc., and its predecessor, as well as its consolidated subsidiary.
Basis of Accounting, Policy [Policy Text Block]	Basis of Presentation The preparation of financial statements in conformity with generally accepted accounting principles requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and the accompanying notes. Actual results could differ from those estimates.
Reclassification, Policy [Policy Text Block]	Reclassifications Certain prior year amounts in the Consolidated Financial Statements have been reclassified to conform to the current year's presentation.
Consolidation, Policy [Policy Text Block]	Principles of Consolidation The Consolidated Financial Statements include the accounts of the Company and its wholly-owned subsidiary, ARPI LLC, which was formed in September 2015 for the sole purpose of facilitating the monetization transaction 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, or the Royalty Monetization. All intercompany accounts and transactions have been eliminated in consolidation. Refer to Note 8 “Liability Related to Sale of Future Royalties” for additional information.
Use of Estimates, Policy [Policy Text Block]	Use of Estimates The preparation of financial statements in conformity with accounting principles generally accepted in the United States requires management to make estimates and assumptions that affect the amounts reported in the Consolidated Financial Statements and accompanying notes. Management evaluates its estimates on an ongoing basis including critical accounting policies. Estimates are based on historical experience and on various other market-specific and other relevant assumptions that the Company believes to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results could differ from those estimates.
Cash, Cash Equivalents, and Marketable Securities [Policy Text Block]	Cash, Cash Equivalents and Marketable Securities 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 and money market instruments. All marketable securities are classified as available-for-sale and consist of U.S. Treasury and U.S. government sponsored enterprise debt securities. These securities are carried at estimated fair value, which is based on quoted market prices or observable market inputs of almost identical assets, with unrealized gains and losses included in accumulated other comprehensive income (loss). The amortized cost of securities is adjusted for amortization of premiums and accretion of discounts to maturity. Such amortization and accretion is included in interest income or expense. The cost of securities sold is based on specific identification. The Company’s investments are subject to a periodic impairment review for other-than-temporary declines in fair value. The Company’s review includes the consideration of the cause of the impairment including the creditworthiness of the security issuers, the number of securities in an unrealized loss position, the severity and duration of the unrealized losses and the Company’s intent and ability to hold the investment for a period of time sufficient to allow for any anticipated recovery in the market value. When the Company determines that the decline in fair value of an investment is below its accounting basis and this decline is other-than-temporary, it reduces the carrying value of the security it holds and records a loss in the amount of such decline.
Fair Value Measurement, Policy [Policy Text Block]	Fair Value of Financial Instruments The Company measures and reports its cash equivalents, investments and financial liabilities at fair value. Fair value is defined as the exchange price that would be received for an asset or an exit price paid to transfer a liability in the principal or most advantageous market for the asset or liability in an orderly transaction between market participants on the measurement date. Valuation techniques used to measure fair value must maximize the use of observable inputs and minimize the use of unobservable inputs. The fair value hierarchy defines a three-level valuation hierarchy for disclosure of fair value measurements as follows: Level I—Unadjusted quoted prices in active markets for identical assets or liabilities; Level II—Inputs other than quoted prices included within Level I that are observable, unadjusted quoted prices in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the related assets or liabilities; and Level III—Unobservable inputs that are supported by little or no market activity for the related assets or liabilities. The categorization of a financial instrument within the valuation hierarchy is based upon the lowest level of input that is significant to the fair value measurement.
Segment Reporting, Policy [Policy Text Block]	Segment Information The Company operates in a single segment, the development and commercialization of product candidates for the treatment of pain. The Company’s contract 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
Concentration Risk, Credit Risk, Policy [Policy Text Block]	Concentration of Risk The Company invests cash that is currently not being used for operational purposes in accordance with its investment policy in debt securities of the U.S. Treasury and 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 Sheet. The Company relies on a single third-party supplier for the supply of sufentanil, the active pharmaceutical ingredient in Zalviso, and various sole-source third-party contract manufacturer organizations to manufacture the Zalviso drug cartridge and device components, including the controller, the dispenser kit and the accessories. To date, the Company has had only two customers. These two customers account for 100% of the revenues for the years ended December 31, 2015, 2014 and 2013. One of these customers accounted for 84% of the accounts receivable balance as of December 31, 2015. The Company did not have an Accounts receivable balance as of December 31, 2014. 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, 2015 is collectible.
Receivables, Policy [Policy Text Block]	Accounts Receivable, Net The Company has receivables from its collaboration partner and the U.S. Department of Defense, or DoD. 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.
Inventory, Policy [Policy Text Block]	Inventories Inventories are valued at the lower of cost or market. 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. 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 market approach as that used to value the inventory. Because selling prices to Grünenthal are set to recover only direct costs with minimal mark up, all inventories are carried at net realizable value.
Property, Plant and Equipment, Policy [Policy Text Block]	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 to five years. Leasehold improvements are amortized over the shorter of the estimated useful life of the improvements or the remaining lease term. Expenditures for repairs and maintenance, which do not extend the useful life of the property and equipment, are expensed as incurred. Upon retirement, the asset cost and related accumulated depreciation are relieved from the accompanying Consolidated Balance Sheets. Gains and losses associated with dispositions are reflected as a component of Other (expense) income in the accompanying Consolidated Statements of Comprehensive Loss.
Impairment or Disposal of Long-Lived Assets, Policy [Policy Text Block]	Impairment of Long-Lived Assets The Company periodically assesses the impairment of long-lived assets and, if indicators of asset impairment exist, the Company assesses the recoverability of the affected long-lived assets by determining whether the carrying value of such assets can be recovered through an analysis of the undiscounted future expected operating cash flows. If impairment is indicated, the Company records the amount of such impairment for the excess of the carrying value of the asset over its estimated fair value. For example, purchased equipment and manufacturing-related facility improvements the Company has made at Patheon’s facility in Ohio, are utilized for continued research and development, commercial manufacturing of Zalviso for Grünenthal and potential commercialization of its other product candidates. If the Company does not receive regulatory approval for its other product candidates, the Company may determine that it is no longer probable that the Company will realize the future economic benefit associated with the costs of these assets through future manufacturing activities, and if so, the Company would record an impairment charge associated with these assets. As of September 30, 2015, the Company remeasured on a non-recurring basis a portion of its leasehold improvements in its corporate offices using Level III valuation techniques. The write down to fair value of these long-lived assets resulted in an impairment charge of $0.5 million in the year ended December 31, 2015, which was recorded in interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss. As of December 31, 2015, the Company has not written down any additional long-lived assets as a result of impairment.
Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block]	Restricted Cash Under the Company’s facility lease and corporate credit card agreements, the Company is required to maintain letters of credit as security for performance under these agreements. The letters of credit are secured by certificates of deposit in amounts equal to the letters of credit, which are classified as restricted cash on the Consolidated Balance Sheets.
Debt, Policy [Policy Text Block]	Debt Issuance Costs Debt issuance costs, which are included in long-term debt, net of current portion, are amortized as interest expense over the contractual terms of the related credit facilities.
Contingent Put Option, Policy [Policy Text Block]	Contingent put option The contingent put option associated with the Company’s loan and security agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, 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 additional information regarding the contingent put option, see Note 7 “Long-Term Debt.”
Warrants, Policy [Policy Text Block]	Warrants Warrants issued in connection with the Company’s Private Placement, completed in June 2012, are recorded as liabilities as they have the potential for cash settlement upon the occurrence of certain transactions (as defined in the warrant; see Note 9 “Warrants”). Changes in the fair value of the warrants are recognized as interest income and other income (expense), net in the Consolidated Statements of Comprehensive Loss.
Revenue Recognition, Policy [Policy Text Block]	Revenue Recognition The Company recognizes revenue when all of the following criteria are met: persuasive evidence of an arrangement exists; delivery has occurred or services have been rendered; the fee is fixed or determinable; and collectability is reasonably assured. Collaboration Revenue Collaboration revenue, which is earned under license agreements with third parties, may include nonrefundable license fees, cost reimbursements, research and development services, commercial manufacturing services, contingent development and commercial milestones and royalties. AcelRx accounts for multiple-element arrangements in accordance with ASC Topic 605-25, Revenue Recognition—Multiple-Element Arrangements For revenue agreements with multiple-element arrangements, such as the collaboration and license agreement with Grünenthal, the Company allocates revenue to each non-contingent element based on the relative selling price of each element. When applying the relative selling price method, the Company determines the selling price for each deliverable using vendor-specific objective evidence, or VSOE, of selling price or third-party evidence, or TPE, of selling price. If neither exists the Company uses best estimated selling price, or BESP, for that deliverable. Revenue allocated is then recognized when the four basic revenue recognition criteria are met for each element. VSOE is based on the price charged when the element is sold separately and is the price actually charged for that deliverable. Establishing VSOE may not be possible for the elements of a license arrangement because each arrangement is unique, an arrangement typically consists of multiple elements and AcelRx has limited history of entering into license arrangements. When VSOE cannot be established, AcelRx attempts to establish the selling price of the elements of a license arrangement based on TPE. TPE is determined based on a competitor’s price for similar deliverables when sold separately. AcelRx may not be able to determine TPE for license arrangements, as they contain a significant level of differentiation such that the comparable pricing of a competitor’s license arrangement with similar functionality cannot be obtained, and AcelRx is therefore unable to reliably determine what a similar competitor’s license arrangement’s selling price would be on a standalone basis. When AcelRx is unable to establish the selling price of an element using VSOE or TPE, BESP is utilized in the allocation of the elements of the arrangement. The objective of the BESP is to determine the price at which AcelRx would transact a sale if the element of the license arrangement were sold on a standalone basis. The process for determining BESPs involves management’s judgment. AcelRx’ process considers multiple factors such as discounted cash flows, estimated direct expenses and other costs and available data, which may vary over time, depending upon the circumstances, and relate to each deliverable. If the estimated obligation period of one or more deliverables should change, the future amortization of the revenue would also change. AcelRx recognizes a contingent milestone payment as revenue in its entirety upon our achievement of the milestone. A milestone is substantive if the consideration earned from the achievement of the milestone (i) is consistent with performance required to achieve the milestone or the increase in value to the delivered item, (ii) relates solely to past performance and (iii) is reasonable relative to all of the other deliverables and payments within the arrangement. Contract and Other Revenue In May 2011, the Company received a grant from the USAMRMC to support the development of ARX-04. The grant provided for the reimbursement of qualified expenses for research and development activities as defined under the terms of the grant agreement. Revenue under the grant agreement was recognized when the related qualified research expenses were incurred. In May 2015, the Company entered into the DoD Contract with the USAMRMC to support the development of ARX-04. The DoD Contract provides for the reimbursement of qualified expenses for development, manufacturing, regulatory and clinical costs outlined in the contract in order to submit an NDA to the FDA, including reimbursement for certain personnel and overhead expenses, as defined under the terms of the contract. Revenue under the contract is recognized when the related qualified expenses are incurred. The Company is entitled to reimbursement of overhead costs associated with the study costs incurred under the DoD Contract. The Company estimates this overhead rate by utilizing forecasted expenditures. Final reimbursable overhead expenses are dependent on direct labor and direct reimbursable expenses throughout the life of the DoD Contract, so it may increase or decrease based on actual expenses incurred.
Cost of Sales, Policy [Policy Text Block]	Cost of Goods Sold Under the Amended Agreements with Grünenthal, the Company will sell Zalviso to Grünenthal at direct cost with minimal markup and will recognize indirect costs as period costs where they are in excess of normal capacity and not realizable on a lower of cost or market basis. Cost of goods sold for Zalviso shipped to Grünenthal includes the inventory costs of API, third-party contract manufacturing costs, packaging and distribution costs, shipping, handling and storage costs, depreciation and costs of the employees involved with production.
Research and Development Expense, Policy [Policy Text Block]	Research and Development Expenses Research and development costs are charged to expense when incurred. Research and development expenses include salaries, employee benefits, including stock-based compensation, consultant fees, laboratory supplies, costs associated with clinical trials and manufacturing, including contract research organization fees, other professional services and allocations of corporate costs. The Company reviews and accrues clinical trial expenses based on work performed, which relies on estimates of total costs incurred based on patient enrollment, completion of patient studies and other events.
Share-based Compensation, Option and Incentive Plans, Director Policy [Policy Text Block]	Stock-Based Compensation Compensation expense for all share-based payment awards made to employees and directors, including employee stock options, restricted stock units 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. Estimates of expected life are primarily determined using the simplified method in accordance with guidance provided by the SEC. Such method was utilized as the Company did not believe its historical option exercise experience, which was limited, provided a reasonable basis upon which to estimate expected term. Volatility is derived from historical volatilities of several public companies within AcelRx’s industry that are deemed to be comparable to AcelRx’s business because AcelRx’s has insufficient history on the volatility of its common stock relative to the expected life assumptions used by the Company. 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. Further, the Company estimates forfeitures at the time of grant and revises those estimates in subsequent periods if actual forfeitures differ from those estimates.
Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block]	Restructuring Costs The Company's restructuring costs consist of employee termination benefit costs. Liabilities for costs associated with the cost reduction plan are recognized when the liability is incurred and are measured at fair value. One-time termination benefits are expensed at the date the entity notifies the employee, unless the employee must provide future service, in which case the benefits are expensed ratably over the future service period.
Interest Expense, Policy [Policy Text Block]	Non-Cash Interest Expense on Liability Related to Sale of Future Royalties In September 2015, the Company sold certain royalty and milestone payment rights from the sales of Zalviso in the European Union by its commercial partner, Grünenthal, pursuant to the Collaboration and License Agreement, dated as of December 16, 2013, as amended, to PDL for an upfront cash purchase price of $65.0 million, referred to as the Royalty Monetization. The Company continues to have 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 the Company’s significant continuing involvement, the Royalty Monetization has been accounted for as a liability that will be amortized using the 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 PDL and payments the Company is required to make to PDL, up to a capped amount of $195.0 million, over the life of the arrangement. The sum of the capped amount of $195.0 million, 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 record interest expense using an estimated interest rate for an arms-length debt transaction. The Company’s estimate of the interest rate under the arrangement is based on the amount of royalty and milestone payments expected to be received by PDL over the life of the arrangement. The Company’s estimate of this total interest expense resulted in an effective annual interest rate of approximately 14%. The Company will periodically assess 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 its 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. 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 PDL agreement
Comprehensive Income, Policy [Policy Text Block]	Comprehensive Loss Comprehensive loss is comprised of net loss and other comprehensive income (loss) and is disclosed in the Consolidated Statements of Comprehensive Loss. For the Company, other comprehensive income (loss) consists of changes in unrealized gains and losses on the Company’s investments.
Income Tax, Policy [Policy Text Block]	Income Taxes Deferred tax assets and liabilities are measured based on differences between the financial reporting and tax basis of assets and liabilities using enacted rates and laws that are expected to be in effect when the differences are expected to reverse. The Company records a valuation allowance for the full amount of deferred assets, which would otherwise be recorded for tax benefits relating to operating loss and tax credit carryforwards, as realization of such deferred tax assets cannot be determined to be more likely than not.
Earnings Per Share, Policy [Policy Text Block]	Net Loss per Share of Common Stock The Company’s basic net loss per share of common stock is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding for the period. The diluted net loss per share of common stock is computed by giving effect to all potential common stock equivalents outstanding for the period determined using the treasury stock method. For purposes of this calculation, convertible preferred stock, options to purchase common stock, restricted stock subject to repurchase, 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 14 “Net Loss per Share of Common Stock.”
New Accounting Pronouncements, Policy [Policy Text Block]	Recently Issued Accounting Pronouncements In May 2014, the Financial Accounting Standards Board, or FASB, issued Accounting Standards Update No. 2014-09, Revenue from Contracts with Customers Revenue from Contracts with Customers (Topic 606): Deferral of the Effective Date In July 2015, the FASB issued ASU 2015-11, Inventory (Topic 330) Related to Simplifying the Measurement of Inventory In April 2015, the FASB issued ASU 2015-03, Interest—Imputation of Interest

Note 2 - Investments and Fair28

Note 2 - Investments and Fair Value Measurement (Tables)	12 Months Ended
	Dec. 31, 2015
Investments And Fair Value Measurement Disclosure [Abstract]
Cash, Cash Equivalents and Investments [Table Text Block]	As of December 31, 2015 Amortized Cost Gross Unrealized Gross Unrealized Fair Cash and cash equivalents: Cash $ 83,112 $ — $ — $ 83,112 U.S. government agency securities 24,809 1 — 24,810 Total cash and cash equivalents 107,921 1 — 107,922 Marketable securities: U.S. government agency securities 5,544 — (2 ) 5,542 Total marketable securities 5,544 — (2 ) 5,542 Total cash, cash equivalents and investments $ 113,465 $ 1 $ (2 ) $ 113,464 As of December 31, 2014 Amortized Cost Gross Unrealized Gross Unrealized Fair Cash and cash equivalents: Cash $ 60,005 $ — $ — $ 60,005 Money market funds 33 — — 33 Total cash and cash equivalents 60,038 — — 60,038 Marketable securities: U.S. government agency securities 15,316 — (4 ) 15,312 Total marketable securities 15,316 — (4 ) 15,312 Total cash, cash equivalents and investments $ 75,354 $ — $ (4 ) $ 75,350
Fair Value Measurements, Recurring and Nonrecurring [Table Text Block]	As of December 31, 2015 Fair Value Level I Level II Level III Assets Money market funds $ 2 $ 2 $ — $ — U.S. government agency obligations 30,352 — 30,352 — Total assets measured at fair value $ 30,354 $ 2 $ 30,352 $ — Liabilities PIPE warrant $ 913 $ — $ — $ 913 Contingent put option 266 — — 266 Total liabilities measured at fair value $ 1,179 $ — $ — $ 1,179 As of December 31, 2014 Fair Value Level I Level II Level III Assets Money market funds $ 33 $ 33 $ — $ — U.S. government agency obligations 15,312 — 15,312 — Total assets measured at fair value $ 15,345 $ 33 $ 15,312 $ — Liabilities PIPE warrant $ 5,577 $ — $ — $ 5,577 Contingent put option 282 — — 282 Total liabilities measured at fair value $ 5,859 $ — $ — $ 5,859
Fair Value of Warrants [Table Text Block]	As of December 31, As of December 31, Market Price $3.85 $6.73 Exercise Price $3.40 $3.40 Risk-free interest rate 1.06% 1.10% Expected volatility 80.0% 61.0% Expected life (in years) 1.92 2.92 Expected dividend yield 0.0% 0.0%
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]	Year Ended Fair value—beginning of period $ 5,859 Change in fair value of PIPE warrants (2,120 ) Exercise of PIPE warrants (2,544 ) Change in fair value of contingent put option associated with Amended Loan Agreement with Hercules (16 ) Fair value—end of period $ 1,179 Year Ended Fair value—beginning of period $ 13,445 Change in fair value of PIPE warrants (6,988 ) Exercise of PIPE warrants (546 ) Change in fair value of contingent put option associated with 2011 loan and security agreement with Hercules (52 ) Fair value—end of period $ 5,859

Note 3 - Inventories (Tables)

Note 3 - Inventories (Tables)	12 Months Ended
	Dec. 31, 2015
Inventory Disclosure [Abstract]
Schedule of Inventory, Current [Table Text Block]	Balance as of Raw materials $ 140 Work-in-process 181 Finished goods 145 Inventories $ 466

Note 4 - Property and Equipme30

Note 4 - Property and Equipment (Tables)	12 Months Ended
	Dec. 31, 2015
Property, Plant and Equipment [Abstract]
Property, Plant and Equipment [Table Text Block]	As of December 31, 2015 2014 Laboratory equipment $ 3,522 $ 2,549 Leasehold improvements 4,609 4,469 Computer equipment and software 266 334 Construction in process 3,950 4,844 Tooling 1,062 527 Furniture and fixtures 55 50 13,464 12,773 Less accumulated depreciation and amortization (4,854 ) (2,955 ) Property and equipment, net $ 8,610 $ 9,818

Note 6 - Collaboration Agreem31

Note 6 - Collaboration Agreement (Tables)	12 Months Ended
	Dec. 31, 2015
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Revenue Recognition, Amended Agreements [Table Text Block]	Years Ended December 31, 2015 2014 2013 License $ 13,167 $ 4,560 $ 27,370 Joint steering committee, research and development services and demonstration devices 1,690 657 — Total $ 14,857 $ 5,217 $ 27,370

Note 7 - Long-term Debt (Tables

Note 7 - Long-term Debt (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure Text Block [Abstract]
Schedule of Maturities of Long-term Debt [Table Text Block]	2016 $ 6,400 2017 18,305 Total payments 24,705 Less amount representing interest (2,539 ) Notes payable, gross 22,166 Unamortized portion of final payment (1,224 ) Unamortized discount on notes payable (20 ) 20,922 Less current portion of notes payable, including unamortized discount 4,541 Notes payable, less current portion $ 16,381

Note 8 - Liability Related to33

Note 8 - Liability Related to Sale of Future Royalties (Tables)	12 Months Ended
	Dec. 31, 2015
Liability Related To Sale Of Future Royalties Disclosure [Abstract]
Other Liabilities [Table Text Block]	Liability related to sale of future royalties—beginning balance (as of December 31, 2014) $ — Net proceeds from sale of future royalties 61,184 Non-cash interest expense recognized 2,428 Payments from AcelRx to PDL — Total liability related to sale of future royalties as of December 31, 2015 63,612 Less: current portion 118 Liability related to sale of future royalties, less current portion $ 63,494

Note 10 - Commitments and Con34

Note 10 - Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2015
Commitments and Contingencies Disclosure [Abstract]
Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block]	Year Ending December 31: 2016 $ 717 2017 737 2018 62 Total minimum payments $ 1,516

Note 12 - Stock-based Compens35

Note 12 - Stock-based Compensation (Tables)	12 Months Ended
	Dec. 31, 2015
Disclosure of Compensation Related Costs, Share-based Payments [Abstract]
Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table Text Block]	December 31, December 31, December 31, Cost of goods sold $ 67 $ — $ — Research and development 2,587 2,252 1,657 General and administrative 2,356 2,188 1,822 Total $ 5,010 $ 4,440 $ 3,479
Schedule of Share-based Compensation, Stock Options, Activity [Table Text Block]	Number Weighted- Weighted- Aggregate (in thousands) December 31, 2014 6,366,763 $ 5.74 Granted 560,500 4.28 Forfeited (997,099 ) 7.22 Expired (372,718 ) 6.19 Exercised (938,497 ) 2.95 December 31, 2015 4,618,949 $ 5.77 7.3 $ 1,079 Vested and exercisable options—December 31, 2015 2,919,289 $ 5.14 6.5 $ 1,036 Vested and expected to vest—December 31, 2015 4,523,784 $ 5.75 7.2 $ 1,076
Schedule of Share Based Compensation Stock Options Outstanding and Exercisable Activity [Table Text Block]	Options Outstanding Options Vested and Exercisable Exercise Prices Number of Weighted-Average Weighted-Average Shares Subject Weighted-Average $ 1.20 - $2.56 463,444 4.1 $ 2.33 463,444 $ 2.33 $ 3.11 - $4.73 1,396,208 7.0 $ 3.67 1,033,204 $ 3.56 $ 5.31 - $8.18 1,820,297 7.7 $ 5.92 948,650 $ 5.64 $ 10.22 - $10.55 939,000 8.3 $ 10.33 473,991 $ 10.35 4,618,949 7.3 $ 5.77 2,919,289 $ 5.14
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions [Table Text Block]	Year Ended December 31, 2015 2014 2013 Expected term (in years) 5.25 - 6.25 5.25 - 6.25 5.75 - 6.25 Risk-free interest rate 1.35% - 1.82% 1.76% - 1.92% 1.02% - 2.96% Expected volatility 72% 69 - 72% 80% Expected dividend rate 0% 0% 0%

Note 13 - Restructuring Costs (

Note 13 - Restructuring Costs (Tables)	12 Months Ended
	Dec. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Related Costs [Table Text Block]	December 31, 2015 Employee termination benefits $ 756 Total restructuring costs $ 756
Schedule of Restructuring Reserve by Type of Cost [Table Text Block]	Employee severance and related costs Balance of restructuring liability at December 31, 2014 $ — Charges 756 Payments (756 ) Balance of restructuring liability at December 31, 2015 $ —

Note 14 - Net Loss per Share 37

Note 14 - Net Loss per Share of Common Stock (Tables)	12 Months Ended
	Dec. 31, 2015
Earnings Per Share [Abstract]
Schedule of Earnings Per Share, Basic and Diluted [Table Text Block]	Years Ended December 31, 2015 2014 2013 (in thousands, except share and per share amounts) Numerator: Net loss used to compute net loss per share Basic $ (24,399 ) $ (33,353 ) $ (23,426 ) Adjustments for change in fair value of warrant liability (2,120 ) (6,988 ) — Diluted $ (26,519 ) $ (40,341 ) $ (23,426 ) Denominator: Weighted average shares outstanding used to compute net loss per share: Basic 44,300,099 43,427,111 39,746,678 Dilutive effect of warrants 168,341 895,186 — Diluted 44,468,440 44,322,297 39,746,678 Net loss per share—basic $ (0.55 ) $ (0.77 ) $ (0.59 ) Net loss per share—diluted $ (0.60 ) $ (0.91 ) $ (0.59 )
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block]	Year Ended December 31, 2015 2014 2013 ESPP and stock options to purchase common stock 4,699,121 6,411,003 4,988,459 Restricted Stock Units — — 65,765 Convertible debt into common stock 553,763 553,763 553,763 Common stock warrants 180,155 180,155 1,674,669

Note 15 - Accrued Liabilities (

Note 15 - Accrued Liabilities (Tables)	12 Months Ended
	Dec. 31, 2015
Payables and Accruals [Abstract]
Schedule of Accrued Liabilities [Table Text Block]	December 31, 2015 2014 Accrued compensation and employee benefits $ 2,876 $ 2,540 Accrued liabilities associated with Grünenthal collaboration — 499 Inventory and other contract manufacturing accruals 272 — Other accrued liabilities 808 615 Total accrued liabilities $ 3,956 $ 3,654

Note 18 - Income Taxes (Tables)

Note 18 - Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2015
Income Tax Disclosure [Abstract]
Schedule of Deferred Tax Assets [Table Text Block]	December 31, December 31, Deferred tax assets: Accruals and other $ 3,162 $ 4,446 Research credits 5,105 4,413 Net operating loss carryforward 30,294 42,330 Section 59(e) R&D expenditures 12,785 17,083 Deferred revenue 21,677 — AMT credit 742 — Total deferred tax assets 73,765 68,272 Valuation allowance (73,765 ) (68,272 ) Net deferred tax assets $ — $ —
Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]	Year Ended December 31, 2015 2014 2013 Tax at statutory federal rate $ (8,037 ) $ (11,392 ) $ (7,965 ) State tax—net of federal benefit 2,853 (2,501 ) (716 ) PIPE Warrant liability (726 ) (2,393 ) 4,898 General Business credits (455 ) (628 ) (1,326 ) Stock Options 1,559 543 Other 73 20 (80 ) Change in valuation allowance 5,493 16,351 5,189 Provision for income taxes $ 760 $ — $ —
Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]	Year Ended December 31, 2015 2014 2013 Unrecognized benefit—beginning of period $ 1,667 $ 1,341 $ 810 Gross decreases—prior period tax positions — — 221 Gross increases—current period tax positions 272 326 310 Unrecognized benefit—end of period $ 1,939 $ 1,667 $ 1,341

Note 20 - Unaudited Quarterly40

Note 20 - Unaudited Quarterly Financial Data (Tables)	12 Months Ended
	Dec. 31, 2015
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information [Table Text Block]	2015 2014 Q1 Q2 Q3 Q4 Q1 Q2 Q3 Q4 Revenues $ 181 $ 1,924 $ 15,428 $ 1,730 $ 95 $ 71 $ 4,825 $ 226 Operating costs and expenses $ 11,581 $ 10,047 $ 8,323 $ 9,266 $ 8,636 $ 12,331 $ 9,894 $ 12,005 Net income / (loss) $ (10,026 ) $ (8,896 ) $ 5,069 $ (10,546 ) $ (9,631 ) $ (10,575 ) $ 671 $ (13,818 ) Net income / (loss) per share (basic) $ (0.23 ) $ (0.20 ) $ 0.11 $ (0.24 ) $ (0.22 ) $ (0.24 ) $ 0.02 $ (0.32 ) Net income / (loss) per share (diluted) $ (0.27 ) $ (0.20 ) $ 0.11 $ (0.24 ) $ (0.22 ) $ (0.30 ) $ (0.13 ) $ (0.32 )

Note 1 - Organization and Sum41

Note 1 - Organization and Summary of Significant Accounting Policies (Details)	12 Months Ended
	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Accounts Receivable, Net, Current (in Dollars)	$ 3,286,000	$ 0
Proceeds from Sale of Royalty and Milestone Rights (in Dollars)	65,000,000
Royalty Arrangment, Maximum Payments (in Dollars)	195,000,000
(in Dollars)	$ 61,184,000
Effective Annual Interest Rate	14.00%
Interest Income [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Asset Impairment Charges (in Dollars)	$ 500,000
Accounting Standards Update 2015-03 [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Prior Period Reclassification Adjustment (in Dollars)		$ 31,000
Sales Revenue, Net [Member] | Customer Concentration Risk [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Number of Major Customers	2	2	2
Concentration Risk, Percentage	100.00%	100.00%	100.00%
Accounts Receivable [Member] | Customer Concentration Risk [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Number of Major Customers	1
Accounts Receivable [Member] | Customer Concentration Risk [Member] | Customer one [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Concentration Risk, Percentage	84.00%
Minimum [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	3 years
Maximum [Member]
Note 1 - Organization and Summary of Significant Accounting Policies (Details) [Line Items]
Property, Plant and Equipment, Useful Life	5 years

Note 2 - Investments and Fair42

Note 2 - Investments and Fair Value Measurement (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Note 2 - Investments and Fair Value Measurement (Details) [Line Items]
Available-for-Sale Securities, Gross Unrealized Gain (Loss), Accumulated in Investments	$ 0	$ 0
Other than Temporary Impairment Losses, Investments, Available-for-sale Securities	0	0
Available-for-sale Securities, Gross Realized Gain (Loss)	0	0
Other Comprehensive Income (Loss), Transfers from Held-to-maturity to Available-for-Sale Securities, Net of Tax	0	$ 0
Interest Income [Member]
Note 2 - Investments and Fair Value Measurement (Details) [Line Items]
Asset Impairment Charges	$ 500,000

Note 2 - Investments and Fair43

Note 2 - Investments and Fair Value Measurement (Details) - Summary of Cash, Cash Equivalents and Investments - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Cash and cash equivalents:
Amortized Cost	$ 113,465	$ 75,354
Gross Unrealized Gains	1
Gross Unrealized Losses	(2)	(4)
Fair Value	113,464	75,350
Cash and Cash Equivalents [Member]
Cash and cash equivalents:
Amortized Cost	107,921	60,038
Gross Unrealized Gains	1
Fair Value	107,922	60,038
Cash and Cash Equivalents [Member] | Cash [Member]
Cash and cash equivalents:
Amortized Cost	83,112	60,005
Fair Value	83,112	60,005
Cash and Cash Equivalents [Member] | Money Market Funds [Member]
Cash and cash equivalents:
Amortized Cost	24,809	33
Gross Unrealized Gains	1
Fair Value	24,810	33
Marketable Securities [Member]
Cash and cash equivalents:
Amortized Cost	5,544	15,316
Gross Unrealized Losses	(2)	(4)
Fair Value	5,542	15,312
Marketable Securities [Member] | U.S. Government Agency Securities [Member]
Cash and cash equivalents:
Amortized Cost	5,544	15,316
Gross Unrealized Losses	(2)	(4)
Fair Value	$ 5,542	$ 15,312

Note 2 - Investments and Fair44

Note 2 - Investments and Fair Value Measurement (Details) - Fair Value of Financial Assets and Liabilities by Level within Fair Value Hierarchy - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Assets
Total assets measured at fair value	$ 30,354	$ 15,345
Liabilities
Total liabilities measured at fair value	1,179	5,859
Money Market Funds [Member]
Assets
Total assets measured at fair value	2	33
U.S. Government Agency Obligations [Member]
Assets
Total assets measured at fair value	30,352	15,312
PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value	913
Contingent Put Option Liability [Member]
Liabilities
Total liabilities measured at fair value	266	282
PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value		5,577
Fair Value, Inputs, Level 1 [Member]
Assets
Total assets measured at fair value	2	33
Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Assets
Total assets measured at fair value	2	33
Fair Value, Inputs, Level 2 [Member]
Assets
Total assets measured at fair value	30,352	15,312
Fair Value, Inputs, Level 2 [Member] | U.S. Government Agency Obligations [Member]
Assets
Total assets measured at fair value	30,352	15,312
Fair Value, Inputs, Level 3 [Member]
Liabilities
Total liabilities measured at fair value	1,179	5,859
Fair Value, Inputs, Level 3 [Member] | PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value	913
Fair Value, Inputs, Level 3 [Member] | Contingent Put Option Liability [Member]
Liabilities
Total liabilities measured at fair value	$ 266	282
Fair Value, Inputs, Level 3 [Member] | PIPE Warrants [Member]
Liabilities
Total liabilities measured at fair value		$ 5,577

Note 2 - Investments and Fair45

Note 2 - Investments and Fair Value Measurement (Details) - Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Pipe Warrants - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Assumptions Used in Black-Scholes Option Pricing Model to Estimate Fair Value of Pipe Warrants [Abstract]
Market Price (in Dollars per share)	$ 3.85	$ 6.73
Exercise Price (in Dollars per share)	$ 3.40	$ 3.40
Risk-free interest rate	1.06%	1.10%
Expected volatility	80.00%	61.00%
Expected life (in years)	1 year 335 days	2 years 335 days
Expected dividend yield	0.00%	0.00%	0.00%

Note 2 - Investments and Fair46

Note 2 - Investments and Fair Value Measurement (Details) - Summary of Changes in Fair Value of Level III Financial Liabilities - Fair Value, Inputs, Level 3 [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Fair value—beginning of period	$ 5,859	$ 13,445
Change in fair value of PIPE warrants	(2,120)	(6,988)
Exercise of PIPE warrants	(2,544)	(546)
Fair value—end of period	1,179	5,859
Hercules 2011 Loan and Security Agreement [Member]
Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]
Change in fair value of contingent put option associated with Amended Loan Agreement with Hercules	$ (16)	$ (52)

Note 3 - Inventories (Details)

Note 3 - Inventories (Details) - Inventory Components $ in Thousands	Dec. 31, 2015USD ($)
Inventory Components [Abstract]
Raw materials	$ 140
Work-in-process	181
Finished goods	145
Inventories	$ 466

Note 4 - Property and Equipme48

Note 4 - Property and Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Note 4 - Property and Equipment (Details) [Line Items]
Depreciation	$ 2,000	$ 900	$ 600
Property, Plant and Equipment, Gross	13,464	12,773
Construction in Progress [Member]
Note 4 - Property and Equipment (Details) [Line Items]
Property, Plant and Equipment, Gross	3,950	4,844
Construction in Progress [Member] | Patheon Cincinnati Facility [Member]
Note 4 - Property and Equipment (Details) [Line Items]
Property, Plant and Equipment, Gross	$ 3,000	$ 3,800

Note 4 - Property and Equipme49

Note 4 - Property and Equipment (Details) - Components of Property and Equipment - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 13,464	$ 12,773
Less accumulated depreciation and amortization	(4,854)	(2,955)
Property and equipment, net	8,610	9,818
Laboratory Equipment [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	3,522	2,549
Leasehold Improvements [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	4,609	4,469
Computer Equipment and Software [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	266	334
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	3,950	4,844
Tooling [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	1,062	527
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Property and Equipment, Gross	$ 55	$ 50

Note 5 - U.S. Department of D50

Note 5 - U.S. Department of Defense Funding (Details) - USD ($) $ in Thousands	Mar. 02, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2013	May. 11, 2015	May. 31, 2011
Note 5 - U.S. Department of Defense Funding (Details) [Line Items]
Grants Receivable							$ 5,600
Government Contract Receivable						$ 17,000
Contracts Revenue		$ 4,406		$ 2,132
Subsequent Event [Member] | Government [Member]
Note 5 - U.S. Department of Defense Funding (Details) [Line Items]
Award Contract, Renewal Term	4 months
Contract and Other Revenue [Member]
Note 5 - U.S. Department of Defense Funding (Details) [Line Items]
Revenue from Grants		0	$ 0	2,100	$ 5,600
Contract and Other Revenue [Member] | Government [Member]
Note 5 - U.S. Department of Defense Funding (Details) [Line Items]
Contracts Revenue		$ 4,400	$ 0	$ 0

Note 6 - Collaboration Agreem51

Note 6 - Collaboration Agreement (Details) - USD ($) $ in Thousands	Jul. 17, 2015	Sep. 30, 2015	Dec. 31, 2013	Sep. 30, 2014	Dec. 31, 2015	Dec. 31, 2015	Jul. 17, 2015	Jul. 16, 2015	Dec. 31, 2014
Note 6 - Collaboration Agreement (Details) [Line Items]
Payments In Exchange For Services Under Collaboration Agreement	$ 700
Amount of Binding Product Forecast Revenue	3,700
Revenue Recognition, Milestone Method, Revenue Recognized		$ 15,000	$ 30,000	$ 5,000			$ 33,300
Revenue Recognition, Milestone Method, Agreed Additional Amount Based on Efforts and Targets					$ 194,500	$ 194,500
Manufacturing Agreement, Percentage for Five Years						100.00%
Manufacturing Agreement, Percentage Therafter						80.00%
Deferred Revenue	54,400						54,400	$ 1,700
Collaboration Agreement Consideration Amount							35,000
Discount on Manufacturing Services					4,400
Committee Participation Services, Allocated					200
Manufacturing Services Revenues Related to Binding Forecast					2,300
Deferred Revenue, Current					2,604	$ 2,604			$ 787
Deferred Revenue, Noncurrent					593	593			$ 1,626
AUSTRALIA
Note 6 - Collaboration Agreement (Details) [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized						166,000
Based upon Net Sales Target Achievements [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Increase (decrease) in Milestone Payments, Related to Net Sales Target	(5,500)
Potential Milestone Payments, Related to Net Sales Target	166,000							$ 171,500
Revenue Recognition, Milestone Method, Agreed Additional Amount Based on Efforts and Targets					166,000	166,000
Based upon Successful Regulatory and Product Development Efforts [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Revenue Recognition, Milestone Method, Agreed Additional Amount Based on Efforts and Targets					28,500	28,500
Previously Delivered License [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Revenue Recognition, Milestone Method, Additional Amount	13,200						13,200
Research and Development and Committee Participation Services [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Revenue Recognition, Milestone Method, Additional Amount	$ 500						$ 500
Zalviso [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized						28,500
Zalviso [Member] | Europe [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Revenue Recognition, Milestone Method, Revenue Recognized						20,000
Collaborative Arrangement [Member]
Note 6 - Collaboration Agreement (Details) [Line Items]
Deferred Revenue, Current					2,600	2,600
Deferred Revenue, Noncurrent					$ 600	$ 600

Note 6 - Collaboration Agreem52

Note 6 - Collaboration Agreement (Details) - Summary of Revenue Recognized under the Amended Agreements - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Note 6 - Collaboration Agreement (Details) - Summary of Revenue Recognized under the Amended Agreements [Line Items]
Total	$ 14,857	$ 5,217	$ 27,370
Collaboration Agreement [Member]
Note 6 - Collaboration Agreement (Details) - Summary of Revenue Recognized under the Amended Agreements [Line Items]
License	13,167	4,560	27,370
Total	14,857	5,217	$ 27,370
Research and Development and Committee Participation Services [Member] | Collaboration Agreement [Member]
Note 6 - Collaboration Agreement (Details) - Summary of Revenue Recognized under the Amended Agreements [Line Items]
Joint steering committee, research and development services and demonstration devices	$ 1,690	$ 657

Note 7 - Long-term Debt (Detail

Note 7 - Long-term Debt (Details)	Sep. 18, 2015$ / sharesshares	Dec. 31, 2014USD ($)	Dec. 31, 2013$ / sharesshares	Dec. 16, 2013USD ($)	Jun. 30, 2011$ / sharesshares	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)$ / sharesshares	Dec. 31, 2011USD ($)shares	Sep. 17, 2015$ / shares	Sep. 24, 2014USD ($)	Jun. 16, 2014USD ($)	Jun. 29, 2011USD ($)
Note 7 - Long-term Debt (Details) [Line Items]
Debt Conversion, Converted Instrument, Warrants or Options Issued (in Shares) | shares									274,508
Repayments of Long-term Debt						$ 4,534,000		$ 16,345,000
Gains (Losses) on Extinguishment of Debt								$ (1,202,000)
Common Stock Warrants Exercised (in Shares) | shares						847,058	135,000	1,135,589
Final Repayment Fee for Early Repayment of Facility							$ 1,700,000
Fair Value of Contingent Put Option Liability		$ 282,000				$ 266,000	282,000
Interest Expense						2,977,000	2,639,000	$ 1,518,000
Hercules Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount													$ 20,000,000
Number of Tranches for Loan and Security Agreement													2
Debt Instrument, Interest Rate, Stated Percentage									8.50%
Investment Warrants, Exercise Price (in Dollars per share) | $ / shares					$ 3.06
Convertible Debt		5,000,000					$ 5,000,000
Debt Instrument, Convertible, Conversion Ratio, Computation, Percentage Used in Numerator							103.00%
Debt Instrument, Convertible, Conversion Ratio, Amount Used in Denominator							$ 9.30
Additional Default Interest Rate							5.00%
Fair Value of Contingent Put Option Liability		282,000		$ 32,000		266,000	$ 282,000
Long-term Line of Credit		24,900,000				20,900,000	24,900,000
Interest Expense						3,000,000	2,600,000
Amortization of Debt Discount (Premium)						$ 800,000	$ 500,000	400,000
Hercules Loan and Security Agreement [Member] | After December 16, 2015 [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Prepayment Charge of Term Loan, Percentage							1.00%
Amended and Restated Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Number of Tranches for Loan and Security Agreement				3
Line of Credit Facility, Maximum Borrowing Capacity				$ 40,000,000
Debt Instrument, Fair Value Disclosure		24,900,000					$ 24,900,000
Gains (Losses) on Extinguishment of Debt								$ 1,200,000
Debt Instrument, Periodic Payment Terms, Balloon Payment to be Paid		$ 1,700,000					$ 1,700,000
Amended and Restated Loan and Security Agreement [Member] | Prime Rate [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Debt Instrument, Interest Rate, Effective Percentage		9.10%					9.10%
Debt Instrument, Basis Spread on Variable Rate		5.25%
Hercules Warrants [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Warrant Exercisable Term			5 years
Debt Conversion, Converted Instrument, Warrants or Options Issued (in Shares) | shares					274,508
Investment Warrants, Exercise Price (in Dollars per share) | $ / shares			$ 6.79		$ 3.06
Common Stock Warrants Exercised (in Shares) | shares	176,730		176,730
Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share) | $ / shares	$ 3.88		$ 9.67					$ 9.67		$ 6.79
Hercules Warrants [Member] | Hercules Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Warrant Exercisable Term									7 years
First Tranche [Member] | Hercules Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount													$ 10,000,000
First Tranche [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount				15,000,000
Repayments of Long-term Debt				$ 8,600,000
Second Tranche [Member] | Hercules Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount									$ 10,000,000
Second Tranche [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Debt Instrument, Face Amount												$ 10,000,000
Third Tranche [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity											$ 15,000,000
Minimum [Member] | Hercules Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Prepayment Charges for Accelerated Repayment of Credit Facility							1.00%
Minimum [Member] | Amended and Restated Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Difference in Discounted Cash Flows, Percentage			10.00%					10.00%
Maximum [Member] | Hercules Loan and Security Agreement [Member]
Note 7 - Long-term Debt (Details) [Line Items]
Prepayment Charges for Accelerated Repayment of Credit Facility							3.00%

Note 7 - Long-term Debt (Deta54

Note 7 - Long-term Debt (Details) - Outstanding Future Payments of Long-term Debt - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Outstanding Future Payments of Long-term Debt [Abstract]
2,016	$ 6,400
2,017	18,305
Total payments	24,705
Less amount representing interest	(2,539)
Notes payable, gross	22,166
Unamortized portion of final payment	(1,224)
Unamortized discount on notes payable	(20)
	20,922
Less current portion of notes payable, including unamortized discount	4,541	$ 6,859
Notes payable, less current portion	$ 16,381	$ 18,015

Note 8 - Liability Related to55

Note 8 - Liability Related to Sale of Future Royalties (Details) $ in Millions	12 Months Ended
	Dec. 31, 2015USD ($)
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Proceeds from Sale of Royalty and Milestone Rights	$ 65
Royalty Arrangment, Maximum Payments	$ 195
Effective Annual Interest Rate	14.00%
Royalty and Milestone Payment Rights [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Proceeds from Sale of Royalty and Milestone Rights	$ 65
PDL [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Percentage of Royalties and Rights under Agreement	75.00%
First Four Commercial Milestones [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Percentage of Royalties and Rights under Agreement	20.00%
First Four Commercial Milestones [Member] | PDL [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Percentage of Royalties and Rights under Agreement	80.00%
Commercial Milestones Value, Maximum Amount Available	$ 35.6
First Four Commercial Milestones [Member] | AcelRX [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Commercial Milestones Value, Maximum Amount Available	$ 44.5
Royalties [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Percentage of Royalties and Rights under Agreement	25.00%
Remaining Commercial and All Development Milestone[Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Percentage of Royalties and Rights under Agreement	100.00%
Commercial Milestones Value	$ 43.5
MAA Aproval [Member]
Note 8 - Liability Related to Sale of Future Royalties (Details) [Line Items]
Revenue Recognition, Milestone Method, Additional Amount	$ 15

Note 8 - Liability Related to56

Note 8 - Liability Related to Sale of Future Royalties (Details) - Activity of Liability Related to Sale of Future Royalties $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Activity of Liability Related to Sale of Future Royalties [Abstract]
Net proceeds from sale of future royalties	$ 61,184
Non-cash interest expense recognized	2,428
Total liability related to sale of future royalties as of December 31, 2015	63,612
Less: current portion	118
Liability related to sale of future royalties, less current portion	$ 63,494

Note 9 - Warrants (Details)

Note 9 - Warrants (Details) $ / shares in Units, $ in Millions	Sep. 18, 2015$ / sharesshares	Dec. 31, 2013USD ($)$ / sharesshares	Feb. 28, 2013shares	Jun. 30, 2012$ / sharesshares	Jun. 30, 2011$ / sharesshares	Jun. 30, 2015USD ($)	Dec. 31, 2015USD ($)shares	Dec. 31, 2014USD ($)shares	Dec. 31, 2013USD ($)$ / sharesshares	Dec. 31, 2011shares	Sep. 17, 2015$ / shares
Note 9 - Warrants (Details) [Line Items]
Common Stock Warrants Exercised							847,058	135,000	1,135,589
Stock Issued During Period Shares Common Stock Warrants Exercised							527,101	91,488	808,078
Debt Conversion, Converted Instrument, Warrants or Options Issued										274,508
Series Warrants [Member]
Note 9 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding							3,425
2012 Private Placement [Member]
Note 9 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding							512,456
Fair Value of Warrant Upon Execution of Securities Purchase Agreement (in Dollars) | $						$ 5.8
Estimated Fair Value of Warrant (in Dollars) | $							$ 0.9
Other Income (in Dollars) | $							$ 2.1	$ 7
Other Expenses (in Dollars) | $									$ 14.1
Pinnacle Loan and Security Agreement [Member] | Series B and Series C Warrants [Member]
Note 9 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding							0
Common Stock Warrants Exercised			228,264
Stock Issued During Period Shares Common Stock Warrants Exercised			58,580
Hercules Warrants [Member]
Note 9 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding							176,730
Common Stock Warrants Exercised	176,730	176,730
Stock Issued During Period Shares Common Stock Warrants Exercised									183,404
Investment Warrants, Exercise Price (in Dollars per share) | $ / shares		$ 6.79			$ 3.06
Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share) | $ / shares	$ 3.88	$ 9.67							$ 9.67		$ 6.79
Warrant Exercisable Term		5 years
Fair Value of Warrant on Date of Issuance (in Dollars) | $		$ 1.1							$ 1.1
Derivative, Price Risk Option Strike Price (in Dollars per Share) | $ / shares		6.79							6.79
Class of Warrant or Right Fair Value Assumption Risk Free Interest Rate		1.55%							1.55%
Class of Warrant or Right Fair Value Assumption Stock Volatility		71.00%							71.00%
Class of Warrant or Right Fair Value Assumption Expected Dividend Yield		0.00%							0.00%
Warrants Not Settleable in Cash, Fair Value Disclosure (in Dollars) | $		$ 0.1							$ 0.1
Debt Conversion, Converted Instrument, Warrants or Options Issued					274,508
PIPE Warrants [Member]
Note 9 - Warrants (Details) [Line Items]
Class of Warrant or Right, Outstanding				2,630,103
Investment Warrants, Exercise Price (in Dollars per share) | $ / shares				$ 3.40
Warrant Exercisable Term						5 years	6 years
Warrants Vesting Condition Description						50%

Note 10 - Commitments and Con58

Note 10 - Commitments and Contingencies (Details) $ in Millions	Oct. 02, 2015ft²	Oct. 02, 2015ft²$ / ft²	May. 01, 2014	May. 31, 2014ft²	Dec. 31, 2015USD ($)	Dec. 31, 2014USD ($)	Dec. 31, 2013USD ($)	Dec. 31, 2011ft²
Note 10 - Commitments and Contingencies (Details) [Line Items]
Rental Rate Per Square Foot (in Dollars per Square Foot) | $ / ft²		2.05
Future Minimum Sublease Rentals, Sale Leaseback Transactions, Next Twelve Months					$ 0.3
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Two Years					0.3
Future Minimum Sublease Rentals, Sale Leaseback Transactions, within Three Years					0
Operating Leases, Rent Expense, Net					$ 0.6	$ 0.5	$ 0.3
Redwood City, California [Member]
Note 10 - Commitments and Contingencies (Details) [Line Items]
Area of Operating Lease (in Square Feet) | ft²	11,871	11,871						13,787
Lessee Leasing Arrangements, Operating Leases, Term of Contract	26 months
Lease Extended Term [Member]
Note 10 - Commitments and Contingencies (Details) [Line Items]
Area of Operating Lease (in Square Feet) | ft²				13,787
Lease Expiration Date			Jan. 31, 2018
Lease Commencement Date				Aug. 1, 2014
Additional Period of Extension in Lease Contract				5 years
Lease Expansion Space [Member]
Note 10 - Commitments and Contingencies (Details) [Line Items]
Area of Operating Lease (in Square Feet) | ft²				12,106
Lease Agreement Term				42 months

Note 10 - Commitments and Con59

Note 10 - Commitments and Contingencies (Details) - Future Minimum Payments Under Lease Agreement $ in Thousands	Dec. 31, 2015USD ($)
Future Minimum Payments Under Lease Agreement [Abstract]
2,016	$ 717
2,017	737
2,018	62
Total minimum payments	$ 1,516

Note 11 - Stockholders' Equity

Note 11 - Stockholders' Equity (Details) - USD ($) $ / shares in Units, $ in Thousands

Jul. 23, 2013

Feb. 10, 2011

Jan. 31, 2016

Jul. 23, 2013

Jun. 30, 2012

Mar. 31, 2011

Nov. 30, 2009

Feb. 29, 2008

Aug. 31, 2006

Dec. 31, 2015

Dec. 31, 2014

Dec. 31, 2013

Dec. 31, 2011

Dec. 31, 2015

May. 29, 2012

Note 11 - Stockholders' Equity (Details) [Line Items]

Common Stock, Par or Stated Value Per Share (in Dollars per share)

$ 0.001

$ 0.001

$ 0.001

Proceeds from Issuance of Class Common Stock Net of Issuance Costs (in Dollars)

$ 47,943

Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period

3 years

2006 Equity Incentive Plan [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

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

1,376,059

375,000

2011 Equity Incentive Plan [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

1,823,307

Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Outstanding

51,693

1,875,000

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

2,654,302

2,654,302

Employee Stock Purchase Plan [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized

250,000

250,000

Share Based Payment Award Number of Shares Authorized

2%

Stock Issued During Period, Shares, Employee Stock Purchase Plans

350,148

Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant

291,207

291,207

Employee Stock Purchase Plan, Shares Issued, Weighted Average Fair Value

4.48

4.35

3.97

Public Offering [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Stock Issued During Period, Shares, New Issues

4,370,000

Common Stock, Par or Stated Value Per Share (in Dollars per share)

$ 11.65

$ 11.65

Proceeds from Issuance Initial Public Offering (in Dollars)

$ 50,900

Proceeds from Issuance of Class Common Stock Net of Issuance Costs (in Dollars)

$ 47,900

2012 Private Placement [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Stock Issued During Period, Shares, New Issues

2,922,337

Warrant Issued to Purchase Common Stock

2,630,103

Gross Proceeds From Issuance of Common Stock and Warrants (in Dollars)

$ 10,000

Stock Offering Costs (in Dollars)

$ 900

Common Stock Shares Issued Description

1

Warrants to Purchase Common Shares

0.9

Class of Warrant or Right, Exercise Price of Warrants or Rights (in Dollars per share)

$ 3.40

Offering Price Per Unit of Warrants Non Affiliated Investors (in Dollars per share)

3.40

Offering Price Per Unit of Warrants Affiliated Investors (in Dollars per share)

3.5125

Closing Consolidated Bid Price of Common Stock (in Dollars per share)

$ 3.40

Minimum Bid Price Per Common Stock (in Dollars per share)

$ 0.1125

Class of Warrant or Rights Exercisable Period from Date of Issuance

6 months

Warrant Expiry From Date of Issue

5 years

Subsequent Event [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized

1,809,906

Subsequent Event [Member] | Employee Stock Purchase Plan [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized

904,953

Maximum [Member] | 2006 Equity Incentive Plan [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Common Stock Voting Rights Percentage

10.00%

Fair Value of Common Stock As Percentage of Option Exercise Price

110.00%

Maximum [Member] | 2011 Equity Incentive Plan [Member]

Note 11 - Stockholders' Equity (Details) [Line Items]

Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period

10 years

Note 12 - Stock-based Compens61

Note 12 - Stock-based Compensation (Details) - USD ($)	1 Months Ended		12 Months Ended
	Jan. 31, 2016	Mar. 31, 2011	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)			$ 2.69	$ 5.57	$ 4.15
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized			$ 7,300,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition			2 years 109 days
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value			$ 5,400,000	$ 3,200,000	$ 1,900,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value			1,300,000	2,300,000	3,600,000
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period (in Shares)		343,815
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value (in Dollars per share)		$ 3.45
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Option Vested In Period Percentage		25.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage Year One		25.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage Year Two		25.00%
Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Vesting Percentage Year Three		25.00%
Restricted Stock or Unit Expense			$ 0	$ 56,000	$ 290,000
2011 Equity Incentive Plan [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant (in Shares)			2,654,302
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period			4 years
Subsequent Event [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized (in Shares)	1,809,906
Restricted Stock Units (RSUs) [Member]
Note 12 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number (in Shares)			0	0

Note 12 - Stock-based Compens62

Note 12 - Stock-based Compensation (Details) - Employee Stock Purchase Plan - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 5,010	$ 4,440	$ 3,479
Cost of Sales [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	67
Research and Development Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	2,587	2,252	1,657
General and Administrative Expense [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items]
Stock-based compensation expense	$ 2,356	$ 2,188	$ 1,822

Note 12 - Stock-based Compens63

Note 12 - Stock-based Compensation (Details) - Option Activity $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Option Activity [Abstract]
December 31, 2014 | shares	6,366,763
December 31, 2014 | $ / shares	$ 5.74
December 31, 2015 | shares	4,618,949
December 31, 2015 | $ / shares	$ 5.77
December 31, 2015	7 years 109 days
December 31, 2015 | $	$ 1,079
Vested and exercisable options—December 31, 2015 | shares	2,919,289
Vested and exercisable options—December 31, 2015 | $ / shares	$ 5.14
Vested and exercisable options—December 31, 2015	6 years 6 months
Vested and exercisable options—December 31, 2015 | $	$ 1,036
Vested and expected to vest—December 31, 2015 | shares	4,523,784
Vested and expected to vest—December 31, 2015 | $ / shares	$ 5.75
Vested and expected to vest—December 31, 2015	7 years 73 days
Vested and expected to vest—December 31, 2015 | $	$ 1,076
Granted | shares	560,500
Granted | $ / shares	$ 4.28
Forfeited | shares	(997,099)
Forfeited | $ / shares	$ 7.22
Expired | shares	(372,718)
Expired | $ / shares	$ 6.19
Exercised | shares	(938,497)
Exercised | $ / shares	$ 2.95

Note 12 - Stock-based Compens64

Note 12 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable - $ / shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Note 12 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Number of Stock Options Outstanding (in Shares) (in Shares)	4,618,949	6,366,763
Weighted-Average Remaining Contractual Life	7 years 109 days
Options Outstanding, Weighted-average Exercise Price per Share	$ 5.77	$ 5.74
Shares Subject to Stock Options (in Shares) (in Shares)	2,919,289
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$ 5.14
Exercise Price Range 1 [Member]
Note 12 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	1.20
Exercise Price Range, Upper Range Limit	$ 2.56
Number of Stock Options Outstanding (in Shares) (in Shares)	463,444
Weighted-Average Remaining Contractual Life	4 years 36 days
Options Outstanding, Weighted-average Exercise Price per Share	$ 2.33
Shares Subject to Stock Options (in Shares) (in Shares)	463,444
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$ 2.33
Exercise Price Range 2 [Member]
Note 12 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	3.11
Exercise Price Range, Upper Range Limit	$ 4.73
Number of Stock Options Outstanding (in Shares) (in Shares)	1,396,208
Weighted-Average Remaining Contractual Life	7 years
Options Outstanding, Weighted-average Exercise Price per Share	$ 3.67
Shares Subject to Stock Options (in Shares) (in Shares)	1,033,204
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$ 3.56
Exercise Price Range 3 [Member]
Note 12 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	5.31
Exercise Price Range, Upper Range Limit	$ 8.18
Number of Stock Options Outstanding (in Shares) (in Shares)	1,820,297
Weighted-Average Remaining Contractual Life	7 years 255 days
Options Outstanding, Weighted-average Exercise Price per Share	$ 5.92
Shares Subject to Stock Options (in Shares) (in Shares)	948,650
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$ 5.64
Exercise Price Range 4 [Member]
Note 12 - Stock-based Compensation (Details) - Stock Options Outstanding, Vested and Exercisable [Line Items]
Exercise Price Range, Lower Range Limit	10.22
Exercise Price Range, Upper Range Limit	$ 10.55
Number of Stock Options Outstanding (in Shares) (in Shares)	939,000
Weighted-Average Remaining Contractual Life	8 years 109 days
Options Outstanding, Weighted-average Exercise Price per Share	$ 10.33
Shares Subject to Stock Options (in Shares) (in Shares)	473,991
Options Vested and Exercisable, Weighted-average Exercise Price per Share	$ 10.35

Note 12 - Stock-based Compens65

Note 12 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Note 12 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option [Line Items]
Expected volatility	72.00%		80.00%
Expected dividend rate	0.00%	0.00%	0.00%
Minimum [Member]
Note 12 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option [Line Items]
Expected term (in years)	5 years 3 months	5 years 3 months	5 years 9 months
Risk-free interest rate	1.35%	1.76%	1.02%
Expected volatility		69.00%
Maximum [Member]
Note 12 - Stock-based Compensation (Details) - Assumptions to Calculate Fair Value of Each Employee Stock Option [Line Items]
Expected term (in years)	6 years 3 months	6 years 3 months	6 years 3 months
Risk-free interest rate	1.82%	1.92%	2.96%
Expected volatility		72.00%

Note 13 - Restructuring Costs66

Note 13 - Restructuring Costs (Details)	3 Months Ended
	Mar. 31, 2015
Restructuring and Related Activities [Abstract]
Restructuring and Related Cost, Number of Positions Eliminated	19
Restructuring and Related Cost, Number of Positions Eliminated, Period Percent	36.00%

Note 13 - Restructuring Costs67

Note 13 - Restructuring Costs (Details) - Restructuring Costs $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 756
Employee Severance [Member]
Restructuring Cost and Reserve [Line Items]
Restructuring Charges	$ 756

Note 13 - Restructuring Costs68

Note 13 - Restructuring Costs (Details) - Restructuring Activity $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)
Restructuring Activity [Abstract]
Charges	$ 756
Payments	$ (756)

Note 14 - Net Loss per Share 69

Note 14 - Net Loss per Share of Common Stock (Details) - Computation of Basic and Diluted Net Loss Per Share of Common Stock - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Net loss used to compute net loss per share
Basic	$ (10,546)	$ 5,069	$ (8,896)	$ (10,026)	$ (13,818)	$ 671	$ (10,575)	$ (9,631)	$ (24,399)	$ (33,353)	$ (23,426)
Adjustments for change in fair value of warrant liability									(2,120)	(6,988)
Diluted									$ (26,519)	$ (40,341)	$ (23,426)
Weighted average shares outstanding used to compute net loss per share:
Basic									44,300,099	43,427,111	39,746,678
Dilutive effect of warrants									168,341	895,186
Diluted									44,468,440	44,322,297	39,746,678
Net loss per share—basic	$ (240)	$ 110	$ (200)	$ (230)	$ (320)	$ 20	$ (240)	$ (220)	$ (0.55)	$ (0.77)	$ (0.59)
Net loss per share—diluted	$ (240)	$ 110	$ (200)	$ (270)	$ (320)	$ (130)	$ (300)	$ (220)	$ (0.60)	$ (0.91)	$ (0.59)

Note 14 - Net Loss per Share 70

Note 14 - Net Loss per Share of Common Stock (Details) - Outstanding Shares of Common Stock Equivalents Excluded from Computation of Diluted Net Loss Per Share - shares	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Employee Stock Option [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock	4,699,121	6,411,003	4,988,459
Restricted Stock Units (RSUs) [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock			65,765
Convertible Debt Securities [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock	553,763	553,763	553,763
Warrant [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Shares of common stock equivalents excluded from the computation of diluted net loss per share of common stock	180,155	180,155	1,674,669

Note 15 - Accrued Liabilities71

Note 15 - Accrued Liabilities (Details) - Accrued Lliabilities - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Note 15 - Accrued Liabilities (Details) - Accrued Lliabilities [Line Items]
Accrued compensation and employee benefits	$ 2,876	$ 2,540
Inventory and other contract manufacturing accruals	272
Other accrued liabilities	808	615
Total accrued liabilities	$ 3,956	3,654
Associated with Grünenthal Collaboration [Member]
Note 15 - Accrued Liabilities (Details) - Accrued Lliabilities [Line Items]
Accrued liabilities associated with Grünenthal collaboration		$ 499

Note 16 - 401(k) Plan (Details)

Note 16 - 401(k) Plan (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Compensation and Retirement Disclosure [Abstract]
Defined Contribution Plan Employer Discretionary Contribution Percentage	4.00%
Contributions By Employer to Postemployment Benefit Obligations	$ 263,000	$ 201,000	$ 143,000

Note 17 - Related Party Trans73

Note 17 - Related Party Transactions (Details)	12 Months Ended
	Dec. 31, 2015USD ($)
Royalty Monetization [Member] | Dr. Hoffman [Member]
Note 17 - Related Party Transactions (Details) [Line Items]
Related Party Transaction, Amounts of Transaction	$ 260,000

Note 18 - Income Taxes (Details

Note 18 - Income Taxes (Details) - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Note 18 - Income Taxes (Details) [Line Items]
Income Tax Expense (Benefit)	$ 760,000	$ 0	$ 0
Valuation Allowances and Reserves, Period Increase (Decrease)	5,500,000	$ 16,400,000	$ 4,800,000
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	$ 742,000
Earliest Tax Year [Member]
Note 18 - Income Taxes (Details) [Line Items]
Open Tax Year	2,005
Latest Tax Year [Member]
Note 18 - Income Taxes (Details) [Line Items]
Open Tax Year	2,015
Subject to Expiration [Member]
Note 18 - Income Taxes (Details) [Line Items]
Operating Loss Carryforwards	$ 1,400,000
Research Tax Credit Carryforward [Member] | Subject to Expiration [Member]
Note 18 - Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount	26,000
Domestic Tax Authority [Member]
Note 18 - Income Taxes (Details) [Line Items]
Operating Loss Carryforwards	73,800,000
Operating Loss Carryforward Attributable to Stock Based Compensation	2,900,000
Deferred Tax Assets, Tax Credit Carryforwards, Alternative Minimum Tax	700,000
Domestic Tax Authority [Member] | Research Tax Credit Carryforward [Member]
Note 18 - Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount	5,000,000
State and Local Jurisdiction [Member]
Note 18 - Income Taxes (Details) [Line Items]
Operating Loss Carryforwards	$ 108,900,000
Net Operating Loss Carryforwards Begins to Expire	2,016
Operating Loss Carryforward Attributable to Stock Based Compensation	$ 2,800,000
State and Local Jurisdiction [Member] | Research Tax Credit Carryforward [Member]
Note 18 - Income Taxes (Details) [Line Items]
Tax Credit Carryforward, Amount	$ 2,800,000

Note 18 - Income Taxes (Detai75

Note 18 - Income Taxes (Details) - Net Deferred Tax Assets - USD ($) $ in Thousands	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Accruals and other	$ 3,162	$ 4,446
Research credits	5,105	4,413
Net operating loss carryforward	30,294	42,330
Section 59(e) R&D expenditures	12,785	17,083
Deferred revenue	21,677
AMT credit	742
Total deferred tax assets	73,765	68,272
Valuation allowance	(73,765)	(68,272)
Net deferred tax assets	$ 0	$ 0

Note 18 - Income Taxes (Detai76

Note 18 - Income Taxes (Details) - Reconciliation of Statutory Federal Income Tax - USD ($)	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Statutory Federal Income Tax [Abstract]
Tax at statutory federal rate	$ (8,037,000)	$ (11,392,000)	$ (7,965,000)
State tax—net of federal benefit	2,853,000	(2,501,000)	(716,000)
PIPE Warrant liability	(726,000)	(2,393,000)	4,898,000
General Business credits	(455,000)	(628,000)	(1,326,000)
Stock Options	1,559,000	543,000
Other	73,000	20,000	(80,000)
Change in valuation allowance	5,493,000	16,351,000	5,189,000
Provision for income taxes	$ 760,000	$ 0	$ 0

Note 18 - Income Taxes (Detai77

Note 18 - Income Taxes (Details) - Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Reconciliation of Beginning and Ending Balance of Unrecognized Tax Benefits [Abstract]
Unrecognized benefit—beginning of period	$ 1,667	$ 1,341	$ 810
Gross decreases—prior period tax positions			221
Gross increases—current period tax positions	272	326	310
Unrecognized benefit—end of period	$ 1,939	$ 1,667	$ 1,341

Note 19 - Subsequent Events (De

Note 19 - Subsequent Events (Details)	Mar. 02, 2016
Government [Member] | Subsequent Event [Member]
Note 19 - Subsequent Events (Details) [Line Items]
Award Contract, Renewal Term	4 months

Note 20 - Unaudited Quarterly79

Note 20 - Unaudited Quarterly Financial Data (Details) - Quarterly Financial Data - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Quarterly Financial Data [Abstract]
Revenues	$ 1,730	$ 15,428	$ 1,924	$ 181	$ 226	$ 4,825	$ 71	$ 95	$ 19,263	$ 5,217	$ 29,502
Operating costs and expenses	9,266	8,323	10,047	11,581	12,005	9,894	12,331	8,636	39,217	42,866	36,169
Net income / (loss)	$ (10,546)	$ 5,069	$ (8,896)	$ (10,026)	$ (13,818)	$ 671	$ (10,575)	$ (9,631)	$ (24,399)	$ (33,353)	$ (23,426)
Net income / (loss) per share (basic) (in Dollars per share)	$ (240)	$ 110	$ (200)	$ (230)	$ (320)	$ 20	$ (240)	$ (220)	$ (0.55)	$ (0.77)	$ (0.59)
Net income / (loss) per share (diluted) (in Dollars per share)	$ (240)	$ 110	$ (200)	$ (270)	$ (320)	$ (130)	$ (300)	$ (220)	$ (0.60)	$ (0.91)	$ (0.59)