This Quarterly Report on Form 10-Q contains forward-looking statements within the meaning of Section 27A of the Securities Act of 1933, as amended, or the Securities Act, and Section 21E of the Securities Exchange Act of 1934, as amended, or the Exchange Act, which are subject to the "safe harbor" created by those sections. Forward-looking statements are based on our management's beliefs and assumptions and on information currently available to them. In some cases you can identify forward-looking statements by words such as "may," "will," "should," "could," "would," "expects," "plans," "anticipates," "believes," "estimates," "projects," "predicts," "potential" and similar expressions intended to identify forward-looking statements. Examples of these statements include, but are not limited to, statements regarding: the implications of interim or final results of our clinical trials, the progress of our research programs, including clinical testing, the extent to which our issued and pending patents may protect our products and technology, our ability to identify new product candidates, the potential of such product candidates to lead to the development of commercial products, our anticipated timing for initiation or completion of our clinical trials for any of our product candidates, our future operating expenses, our future losses, our future expenditures for research and development, and the sufficiency of our cash resources. Our actual results could differ materially from those anticipated in these forward-looking statements for many reasons, including the risks faced by us and described in Part II, Item 1A of this Quarterly Report on Form 10-Q and our other filings with the SEC. You should not place undue reliance on these forward-looking statements, which apply only as of the date of this Quarterly Report on Form 10-Q. You should read this Quarterly Report on Form 10-Q completely and with the understanding that our actual future results may be materially different from those we expect. Except as required by law, we assume no obligation to update these forward-looking statements, whether as a result of new information, future events or otherwise.

The following discussion and analysis should be read in conjunction with the unaudited financial statements and notes thereto included in Part I, Item 1 of this Quarterly Report on Form 10-Q and with the audited consolidated financial statements and related notes thereto included as part of our Annual Report on Form 10-K for the year ended December 31, 2011.

About AcelRx Pharmaceuticals

We are a development stage specialty pharmaceutical company focused on the development and commercialization of innovative therapies for the treatment of acute and breakthrough pain. We were founded to solve the problems associated with post-operative intravenous patient-controlled analgesia, or IV PCA. Although widely used, IV PCA has been shown to cause harm to patients following surgery because of the side effects of morphine, the invasive IV route of delivery and the inherent potential for programming and delivery errors associated with the complexity of infusion pumps. In March 2012, we initiated the first of three Phase 3 clinical trials for our lead product candidate, the Sufentanil NanoTab PCA System, or ARX-01 System, or ARX-01. In April 2012, we initiated the second Phase 3 trial, an open-label active-comparator study. The final planned Phase 3 efficacy and safety study, a double-blind, placebo-controlled trial is expected to begin in the third quarter of 2012. We expect top-line data from all three Phase 3 trials in late 2012 or early 2013.

The ARX-01 System is designed to address the problems associated with IV PCA by utilizing:

• Sufentanil, a high therapeutic index opioid;

• NanoTabs, our proprietary, non-invasive sublingual dosage form; and

• our novel handheld PCA device that enables simple patient-controlled delivery of NanoTabs in the hospital setting and eliminates the risk of programming errors.

We have completed Phase 2 clinical development for two additional product candidates, the Sufentanil NanoTab BTP Management System, or ARX-02, for the treatment of cancer breakthrough pain, or BTP, and the Sufentanil/Triazolam NanoTab, or ARX-03, designed to provide mild sedation, anxiety reduction and pain relief for patients undergoing painful procedures in a physician's office. In May 2011, we announced that the US Army Medical Research and Material Command, or USAMRMC, awarded us a $5.6 million grant to support the development of a new product candidate, ARX-04, a Sufentanil NanoTab for the treatment of moderate-to-severe acute pain. Under the terms of the grant, the USAMRMC will reimburse us for development, manufacturing and clinical expenses 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.

Development of therapeutic products is costly and is subject to a lengthy and uncertain regulatory process by the United States Food and Drug Administration, or FDA. Adverse events in both our own clinical program and other programs may have a negative impact on regulatory approval, the willingness of potential commercial partners to enter into agreements and the perception of the public.

Product Development

ARX-01

We continue to make progress in the development of our lead product candidate, ARX-01, including the following activities:

• In March 2012, we initiated the first of three Phase 3 clinical trials, a double-blind, placebo-controlled efficacy and safety trial of patients with post-operative pain following open-abdominal surgery. We expect top-line data for this trial in the second half of 2012;

• In April 2012, we initiated our second planned Phase 3 clinical trial, an open-label active-comparator study comparing ARX-01 to the current standard of care, IV PCA morphine, in patients with post-operative pain following open-abdominal surgery or major orthopedic surgery. We expect top-line data for this trial in the second half of 2012;

• In the third quarter of 2012, we plan to initiate our third planned Phase 3 clinical trial, a double-blind, placebo-controlled efficacy and safety study of patients with post-operative pain following hip and knee replacement surgeries. We expect top-line data for this trial in late 2012 or early 2013.

ARX-04

We continue to make progress towards the initiation of our planned ARX-04 Phase 2 dose-finding clinical trial. In October 2011, we filed an Investigational New Drug application for ARX-04, our product candidate for management of moderate-to-severe acute pain, with the FDA, and we plan to initiate the Phase 2 study contingent on approval of the proposed clinical protocol for the study from the USAMRMC.

Future development of ARX-02 and ARX-03 is contingent upon additional funding or establishing corporate partnerships.

Financial Overview

We are a development stage company with a limited operating history. We have incurred net losses since inception and expect to incur losses in the future as we continue our research and development activities. To date, we have funded our operations primarily from the private placement of convertible preferred stock, proceeds from our initial public offering, or IPO, and proceeds received from our debt financings.

From inception through March 31, 2012, we have received net proceeds of $54.9 million from the sale of convertible preferred stock and $41.4 million from debt financings. In February 2011, we completed an IPO, pursuant to which we sold 8,000,000 shares of our common stock at a public offering price of $5.00 per share for an aggregate offering price of $40.0 million. As a result of the offering, we received net proceeds of $34.9 million, after underwriting discounts, commissions and offering expenses totaling $5.1 million. In June 2011, we entered into a loan and security agreement with Hercules Technology II, L.P. and Hercules Technology Growth Capital, Inc., collectively referred to as Hercules, under which we may borrow up to $20.0 million in two tranches of $10.0 million each, represented by secured convertible term promissory notes. We drew the first tranche of $10.0 million upon the closing of the transaction on June 29, 2011 and the second tranche of $10.0 million in December 2011. The interest rate is initially 8.50%, with 12 months of interest only payments. We used a portion of the proceeds from the first tranche to repay the remaining obligations under that certain loan and security agreement between us and Pinnacle Ventures, L.L.C, or Pinnacle, dated September 2008.

Since our inception in July 2005, we have not generated any revenue from the sale of our products and do not anticipate generating any product revenues for the foreseeable future. We have recognized revenue associated with our grant from the USAMRMC of $1.4 million since inception of the grant, but continued funding from the USAMRMC is contingent upon their review and approval of our continued research and development activities

associated with the grant. In addition, there can be no assurance that we will receive other research-related grant awards or produce other collaborative agreement revenues in the future. We have incurred losses and generated negative cash flows from operations since inception. Our net losses were $7.1 million for the three months ended March 31, 2012 and $20.1 million during the year ended December 31, 2011. As of March 31, 2012, we had cash, cash equivalents and investments totaling $27.6 million compared to $35.8 million as of December 31, 2011. As of March 31, 2012, we had an accumulated deficit of $95.7 million.

Research and development expenses consist primarily of salaries and personnel related expenses, stock-based compensation expenses, laboratory supplies, pre-clinical and clinical studies, manufacturing expenses, allocated facilities expenses and subcontracted research and development expenses. We believe that continued investment in research and development is critical to attaining our strategic objectives. We expect these expenses will increase as we focus on the development of our product candidates. Additionally, in order to develop our product candidates as commercially viable therapeutics, we expect to expend additional resources for expertise in the manufacturing, regulatory affairs and clinical research aspects of pharmaceutical development.

General and administrative expenses consist primarily of salaries and personnel related expenses for executive, finance and administrative personnel, stock-based compensation expenses, professional fees, allocated facilities expenses, patent prosecution expenses and other general corporate expenses. As we pursue commercial development of our product candidates we expect the business aspects of our company to become more complex. We may be required in the future to add personnel and incur additional costs related to the maturation of our business.

Critical Accounting Estimates

The accompanying discussion and analysis of our financial condition and results of operations are based upon our financial statements and the related disclosures, which have been prepared in accordance with accounting principles generally accepted in the United States. The preparation of these financial statements requires us to make estimates, assumptions and judgments that affect the reported amounts in our financial statements and accompanying notes. We base our estimates on historical experience and on various other assumptions that we believe 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 may differ from these estimates under different assumptions or conditions. To the extent that there are material differences between these estimates and actual results, our future financial statement presentation, financial condition, results of operations and cash flows will be affected. Our critical accounting policies and estimates are detailed in our Annual Report on Form 10-K for the year ended December 31, 2011. There have been no significant changes in our critical accounting policies and estimates during the three months ended March 31, 2012 from those previously disclosed in our Annual Report on Form 10-K.

Results of Operations

Three Months Ended March 31, 2012 and 2011

Revenue

To date, we have not generated any revenue from commercial sales. We do not expect to receive any such revenue from any product candidate that we develop until we obtain regulatory approval and commercialize our products or enter into collaborative agreements with third parties. In May 2011, we received a grant award of $5.6 million from the USAMRMC for the development of ARX-04, a Sufentanil NanoTab for the treatment of moderate-to-severe acute pain. Revenue related to this grant award is recognized as the related research and development expenses are incurred.

Revenue for the three months ended March 31, 2012 was $0.3 million, and was generated from our grant with the USAMRMC. We did not generate any revenue for the three months ended March 31, 2011. From inception of the grant through March 31, 2012, we have generated revenue of $1.4 million from the grant with the USAMRMC.

Research and Development Expenses

Conducting research and development is central to our business model. The majority of our operating expenses in 2012 and 2011 have been for research and development activities related to ARX-01. Research and development expenses included the following:

• expenses incurred under agreements with contract research organizations and clinical trial sites;

• employee- and consultant-related expenses, which include salaries, benefits and stock-based compensation;

• payments to third party pharmaceutical and engineering development contractors;

• payments to third party manufacturers; and

Product candidates in late stages of clinical development generally have higher development costs than those in earlier stages of clinical development, primarily due to the increased size and duration of late stage clinical trials. We plan to increase our research and development expenses for the foreseeable future as we seek to complete development of ARX-01, execute activities associated with the clinical work related to ARX-04 and subsequently advance the development of ARX-02 and ARX-03, provided that additional funding or corporate partnership resources are available to support the two latter programs.

We track external development expenses on a program-by-program basis. Our development resources are shared among all of our programs. Compensation and benefits, facilities, depreciation, stock-based compensation, and development support services are not allocated specifically to projects and are considered research and development overhead. Below is a summary of our research and development expenses during the three months ended March 31, 2012 and 2011 (in thousands):

                                                          Three months
                                                        ended March 31,
                                                        2012        2011
            ARX-01                                    $  3,023     $   751
            ARX-04                                         169          -
            Overhead                                     1,579       1,195

            Total research and development expenses   $  4,771     $ 1,946

Due to the inherently unpredictable nature of product development, development timelines and the probability of success, development costs can differ materially from expectations. While we are currently focused on advancing ARX-01 and ARX-04, and subsequently ARX-02 and ARX-03, our future research and development expenses will depend on the clinical success of each product candidate as well as ongoing assessments of the commercial potential of our product candidates. In addition, we cannot predict which product candidates may be subject to future collaborations, when these arrangements will be secured, if at all, and to what degree these arrangements would affect our development plans and capital requirements. We expect our research and development expenses to substantially increase as we progress with our ARX-01 Phase 3 clinical trials, and subject to additional funding, complete all the requisite preparatory activities to submit an NDA to the FDA. Additionally, upon receipt of approval from USAMRMC, our research and development expenses will increase as we initiate the planned ARX-04 Phase 2 clinical trial.

Total research and development expenses for the three months ended March 31, 2012 and 2011 were as follows (in thousands, except percentages):

                                                                                                   Percentage
                                                                                 Increase/         Increase/
                                           Three Months Ended March 31,          (Decrease)        (Decrease)

The $2.8 million increase during the three months ended March 31, 2012 as compared to the three months ended March 31, 2011 was primarily attributable to an increase of $2.3 million related to Phase 3 clinical trial development for our ARX-01 program. In addition, there was an increase of $0.2 million related to our ARX-04 development program, which we initiated in the second quarter of 2011, and an increase in personnel related expenses, including stock-based compensation.

General and Administrative Expenses

General and administrative expenses consisted primarily of salaries, benefits and stock-based compensation for personnel in administration and finance and business development activities. Other significant expenses included legal expenses to pursue patent protection of our intellectual property, allocated facility costs and professional fees for general legal, audit and consulting services. We expect general and administrative expenses to increase in connection with operating as a public company and as we continue to build our corporate infrastructure in support of continued development of our product candidates.

Total general and administrative expenses for the three months ended March 31, 2012 and 2011 were as follows (in thousands, except percentages):

                                                                                                      Percentage
                                                                                   Increase/          Increase/
                                            Three Months Ended March 31,           (Decrease)         (Decrease)

The $0.5 million increase during the three months ended March 31, 2012 as compared to the three months ended March 31, 2011 was primarily due to an increase in patent prosecution related activities, marketing research efforts and personnel related expenses, including stock-based compensation.

Interest Expense (in thousands, except percentages)



                                                                               Percentage
                                                              Increase/        Increase/
                        Three Months Ended March 31,         (Decrease)        (Decrease)

The $0.8 million decrease during the three months ended March 31, 2012 as compared to the three months ended March 31, 2011 was primarily attributable to interest and the debt discount amortization recorded during the three months ended March 31, 2011 related to convertible promissory notes issued in September 2010, which converted immediately prior to the IPO in February 2011. As a result of the conversion of the notes, $1.1 million in unamortized debt discounts was recognized as interest expense during the three months ended March 31, 2011. Interest expense for the three months ended March 31, 2012 reflects interest related to our loan and security agreement with Hercules.

Other Income (Expense), net

Other income (expense), net consisted primarily of the change in the fair value of our then-outstanding warrants to purchase convertible preferred stock. Our warrants to purchase convertible preferred stock were classified as liabilities and, as such, were remeasured to fair value at each balance sheet date with the corresponding gain or loss from the adjustment recorded as other income (expense), net. Upon the completion of our IPO, all of our warrants to purchase convertible preferred stock were remeasured to fair value and were either exercised or converted into warrants to purchase common stock. At that time, the then-current aggregate fair value of these warrants was reclassified from liabilities to additional paid-in capital and we will no longer remeasure the liability associated with these warrants to fair value. Other income (expense), net also included the change in fair value of our contingent put option liability associated with our loan and security agreement with Hercules.

Total other income (expense), net for the three months ended March 31, 2012 and 2011 was as follows (in thousands, except percentages):

                                                                                                       Percentage
                                                                                   Increase/           Increase/
                                           Three Months Ended March 31,            (Decrease)          (Decrease)

The $1.6 million decrease in other income (expense) during the three months ended March 31, 2012 as compared to the three months ended March 31, 2011 was primarily attributable to the change in the fair value of our warrants to purchase convertible preferred stock and the write-off of the call option related to the convertible promissory notes issued in September 2010, which expired upon closing of the IPO in February 2011. Other income (expense) during the three months ended March 31, 2012 primarily reflects the change in estimated fair value of the contingent put option liability associated with our loan and security agreement with Hercules.

Liquidity and Capital Resources

Liquidity

Since inception, we have incurred significant annual net losses and we have funded our operations primarily through the issuance of equity securities and debt financings. From inception through March 31, 2012, we have received net proceeds of $54.9 million from the sale of convertible preferred stock, $34.9 million from our IPO and $41.4 million from our debt arrangements. We have incurred losses and generated negative cash flows from operations since inception, and we expect to continue to incur significant and increasing losses and negative cash flows for the foreseeable future.

As of March 31, 2012, we had cash, cash equivalents and investments totaling $27.6 million compared to $35.8 million as of December 31, 2011. The decrease was primarily attributable to capital required to fund our continuing operations, including advancement of our lead product candidate, ARX-01. Our most significant use of capital pertains to salaries and benefits for our employees and clinical trial expenses related to our development programs.

Our cash and investment balances are held in a variety of interest bearing instruments, including obligations of U.S. government agencies, U.S. treasury debt securities and money market funds. Cash in excess of immediate requirements is invested with a view toward capital preservation and liquidity.

Cash Flows

The following is summary of our cash flows for the periods indicated and has
been derived from our condensed financial statements which are included
elsewhere in this Form 10-Q (in thousands):



                                                          Three Months Ended March 31,
                                                           2012                  2011
Net cash used in operating activities                  $      (7,761 )       $      (1,375 )
Net cash provided by (used in) investing activities            4,347                (2,437 )
Net cash provided by financing activities                         89                33,963

Cash Flows from Operating Activities

The primary use of cash for our operating activities during these periods was to fund the development of our product candidates. Our cash used for operating activities also reflected changes in our working capital and adjustments for non-cash charges, such as depreciation and amortization of our fixed assets, stock-based compensation, interest expense related to our debt financings, and the revaluation of our convertible preferred stock warrant liability.

Cash used in operating activities of $7.8 million during the three months ended March 31, 2012 reflected a net loss of $7.1 million, partially offset by aggregate non-cash charges of $0.9 million and a net change of $1.6 million in our net operating assets and liabilities. Non-cash charges primarily included $0.5 million for stock-based compensation and $0.2 million for interest on our debt. The net change in our operating assets and liabilities was primarily a result of an increase in prepaid expenses and other current assets of $1.1 million, primarily due to prepayments related to our Phase 3 clinical trials for ARX-01.

Cash used in operating activities of $1.4 million during the three months ended March 31, 2011 reflected a net loss of $3.2 million, partially offset by a net change of $1.8 million in our net operating assets and liabilities. In addition, we had non-cash charges of $1.2 million for interest on our debt, $0.1 million of depreciation and amortization and $0.3 million in stock-based compensation which were offset by $1.7 million of non-cash benefits for the revaluation of . . .