Top-line Data Show AcelRx Pharmaceuticals' ARX-04 Achieves Primary Endpoint in Dose-Finding Phase 2 Clinical Trial

Top-line Data Show AcelRx Pharmaceuticals' ARX-04 Achieves Primary Endpoint in
                     Dose-Finding Phase 2 Clinical Trial

- Patients in the 30 mcg sufentanil NanoTab treatment group experienced
significantly greater reduction in pain as measured by SPID-12 vs. placebo -

- ARX-04 is a rapid-onset, non-invasive investigational pain medication being
evaluated for the short-term treatment of acute moderate-to-severe pain in a
range of ambulatory care environments -

PR Newswire

REDWOOD CITY, Calif., April 24, 2013

REDWOOD CITY, Calif., April 24, 2013 /PRNewswire/ --- AcelRx Pharmaceuticals,
Inc. (Nasdaq: ACRX), a specialty pharmaceutical company focused on the
development and commercialization of innovative therapies for the treatment of
acute and breakthrough pain, today announced top-line results demonstrating
that a placebo-controlled, dose-finding, Phase 2 study of its investigational
single-dose sublingual sufentanil NanoTab for acute pain, ARX-04, successfully
met its primary endpoint. Results demonstrated that patients receiving 30 mcg
sufentanil NanoTab doses, administered by a healthcare professional, no more
frequently than once per hour, had significantly greater pain reduction as
measured by Summed Pain Intensity Difference to baseline during the 12-hour
study period (SPID-12) than placebo-treated patients (p=0.003). Adverse
events reported in the study were generally mild-to-moderate in nature, with
two serious adverse events of post-surgical infection reported, both of which
were determined by the investigator to be unrelated to study drug. Two
patients dropped out of the study due to adverse events, one patient's
discontinuation considered unrelated to study drug, and the other considered
probably related to study drug, both in the 30 mcg-treated group.

"The goal of this program, to find an effective sublingual sufentanil dose
that could be administered less frequently by a healthcare professional than
our patient-administered ARX-01 product candidate, has been met", said Dr.
Pamela Palmer, Chief Medical Officer, AcelRx Pharmaceuticals. "There is a
need for a non-invasive, rapid-onset strong analgesic to provide short-term
treatment of pain for the wounded soldier on the battlefield, the trauma
victim at the site of a road-traffic accident, the migraine patient in the
emergency room, or in general for patients in moderate-to-severe acute pain
where intravenous access is not readily available."

This study randomized 101 patients following bunionectomy surgery in a 2:2:1
ratio to 30 mcg sufentanil, 20 mcg sufentanil or placebo treatment arms. The
intent-to-treat (ITT) population in this study averaged 42.5 years of age with
an average Body Mass Index of 28.2, and was evenly balanced for males and
females (51%:49%) and ethnicity (54% Caucasian:46% non-Caucasian). Ninety-one
percent of patients entering the study completed the full 12-hour study
period. SPID-12 scores were +6.53 for 30 mcg sufentanil-treated patients and
-7.12 for placebo-treated patients, the difference between the two groups
being highly statistically significant (p=0.003). The 20 mcg
sufentanil-treated patients did not achieve SPID-12 scores that differentiated
from placebo.

"The results from this study, funded by the U.S. Army Medical Research and
Materiel Command, provide further validation of our sufentanil NanoTab product
platform as an effective treatment for moderate-to-severe acute pain," said
Richard King, president and CEO of AcelRx. "AcelRx will present these positive
top-line data to USAMRMC, and intends to hold an End of Phase 2 meeting with
the FDA to define the Phase 3 clinical program for ARX-04."

About ARX-04

ARX-04 is a product candidate in development for the treatment of
moderate-to-severe acute pain, consisting of sufentanil, a high therapeutic
index opioid, in AcelRx's proprietary NanoTab technology that enables rapid
sublingual absorption when the NanoTab is placed under the tongue. As a
result, sufentanil NanoTabs are designed to provide rapid onset of analgesia
in a non-invasive method of administration and display a consistent
pharmacokinetic profile due to a high percentage of drug being absorbed
sublingually instead of through the gastrointestinal tract. We believe ARX-04
may ultimately be proven beneficial in a variety of medically supervised
settings, including use in battlefield casualty treatment, by paramedics
during patient transport, in the emergency room, for non-surgical patients
experiencing pain in the hospital, or for post-operative patients, following
either short-stay or ambulatory surgery, who do not require more long-term
patient-controlled analgesia (PCA). According to the Centers for Disease
Control and Prevention data, there are more than 45 million injury-related
emergency department visits and 43 million ambulatory surgery procedures
annually in the United States.

About Acute Pain

In situations of trauma or injury, it is advantageous to have a rapid-acting,
non-invasive method of treating acute pain. In the battlefield, in the
emergency room and in ambulatory care environments, patients often do not have
immediate intravenous, or IV, access available. Intramuscular injections are
the current standard of care on the battlefield, but they are invasive,
painful, and present an increased risk of infection to both patient and
healthcare professional. In addition, in cases of severe trauma where the
patient is often in hypovolemic shock and muscles are not well perfused, pain
medication given by intramuscular injection may not readily reach the blood
stream to provide pain relief, rendering this route of delivery suboptimal.
Oral pills and liquids generally have slow and erratic onset of analgesia.
Even patients with IV access may have undesirable side effects with the
commonly used IV opioids morphine and hydromorphone, such as sedation or
oxygen desaturation. Moreover, IV dosing results in high peak plasma levels,
thereby limiting the opioid dose and requiring frequent redosing intervals to
titrate to satisfactory analgesia. Additional treatment options are needed
which can safely and rapidly treat acute pain, in both civilian and military

About AcelRx Pharmaceuticals, Inc.

AcelRx Pharmaceuticals, Inc. is a specialty pharmaceutical company focused on
the development and commercialization of innovative therapies for the
treatment of acute and breakthrough pain. AcelRx's lead product candidate,
the Sufentanil NanoTab PCA System (ARX-01 or the NanoTab System), is designed
to solve the problems associated with post-operative intravenous
patient-controlled analgesia, which 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 complexity of infusion pumps. AcelRx has announced
results from two Phase 3 clinical trials for the NanoTab System, and a third
Phase 3 study has completed enrollment, with data expected in the second
quarter of 2013. A New Drug Application submission is planned for the third
quarter of 2013. AcelRx has two additional product candidates, ARX-02 and
ARX-03, which have completed Phase 2 clinical development. For additional
information about AcelRx's clinical programs please visit .

Forward Looking Statements

This press release contains forward-looking statements, including, but not
limited to, statements related to the process and timing of anticipated future
clinical development of AcelRx Pharmaceuticals' product candidates, including
the advancement of ARX-04 beyond Phase 2 clinical trials and the potential
submission of an NDA for the NanoTab System and the timing thereof,
therapeutic and commercial potential of the NanoTab System, and the
anticipated timing of the Phase 3 results and therapeutic and commercial
potential of other AcelRx Pharmaceuticals' product candidates. These
forward-looking statements are based on AcelRx Pharmaceuticals' current
expectations and inherently involve significant risks and uncertainties.
AcelRx Pharmaceuticals' actual results and the timing of events could differ
materially from those anticipated in such forward-looking statements as a
result of these risks and uncertainties, which include, without limitation,
risks related to: the ability of AcelRx Pharmaceuticals to successfully
complete the clinical trials for the sufentanil NanoTab System; that
subsequent analyses of data by regulatory agencies may be subject to differing
interpretations; the success, cost and timing of all product development; the
uncertain clinical development process, including the risk that clinical
trials have an effective design or deliver data on schedule; AcelRx
Pharmaceutical's ability to attract funding partners or collaborators with
development, regulatory and commercialization expertise; its ability to obtain
sufficient financing to complete registration of its product candidates in the
United States and Europe; its ability to obtain and maintain regulatory
approvals of its product candidates in the United States and Europe; the
market potential for its product candidates; the accuracy of AcelRx
Pharmaceuticals' estimates regarding expenses, capital requirements and needs
for financing; and other risks detailed in the "Risk Factors" and elsewhere in
AcelRx Pharmaceuticals' U.S. Securities and Exchange Commission filings and
reports, including its Annual Report on Form 10-K filed with the SEC on March
12, 2013. AcelRx Pharmaceuticals undertakes no duty or obligation to update
any forward-looking statements contained in this release as a result of new
information, future events or changes in its expectations.


SOURCE AcelRx Pharmaceuticals, Inc.

Contact: Jim Welch, Chief Financial Officer, AcelRx Pharmaceuticals, Inc.,
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