Rexahn Pharmaceuticals Announces Publication of Study Validating Mechanism of Action of Serdaxin®

Study sheds light on Serdaxin as an enhancer of dopamine and serotonin release (SERDA);

Novel mechanism may be able to address both negative mood and loss of positive mood in depressed patients

ROCKVILLE, Md.--(BUSINESS WIRE)-- Rexahn Pharmaceuticals, Inc. (NYSE Amex: RNN), a clinical stage pharmaceutical company developing and commercializing potential best in class oncology and CNS therapeutics, today announced the publication of a peer reviewed study in Neuroscience Letters that validates the mechanism of action of clavulanic acid, the active compound in Serdaxin^®, the company’s lead CNS drug currently in Phase II clinical development for major depressive disorder.

The published study, “Clavulanic acid increases dopamine release in neuronal cells through a mechanism involving enhanced vesicle trafficking,” shows that clavulanic acid enhances release of neurotransmitters such as dopamine in the brain cell by interacting with key proteins for vesicle trafficking and fusion.

“This study is significant because it confirms at the molecular and cellular levels how Serdaxin enhances the release of neurotransmitters in the brain. Previous studies demonstrated the release of serotonin and dopamine in the brain by clavulanic acid in live animals. These results strongly support that Serdaxin's CNS effects may be due to an enhanced release of the dual neurotransmitters, called as the SERDA mechanism.” said Dr. Chang Ahn, Chairman and CEO of Rexahn.

Dr. Ahn elaborated, “Because the effectiveness of currently marketed therapies that modulate serotonin reuptake is significantly limited, there exists very strong therapeutic needs for depression patients who are non-responders, are relapsed, or are non-compliant due to adverse reactions of those therapeutics. Serdaxin positions itself to address these therapeutic and safety needs as the first SERDA antidepressant with excellent safety profile.”

Dr. Michael Thase, Chairman of the Depression Scientific Advisory Board of Rexahn, said, “This study illustrates that clavulanic acid may have important effects on monoaminergic neurotransmission, that are the result of interaction with vesicle trafficking and fusion through a novel mechanism involving Munc18 and Rab proteins. Enhancing the release of both dopamine and serotonin to physiological levels in the brain may prove to have novel therapeutic implications for those who suffer from major depressive disorder and other neurological disorders.”

About Rexahn Pharmaceuticals, Inc.

Rexahn Pharmaceuticals is a clinical stage pharmaceutical company dedicated to developing and commercializing first in class and market leading therapeutics for cancer, CNS disorders, sexual dysfunction and other unmet medical needs. Rexahn currently has three drug candidates in Phase II clinical trials, Archexin®, Serdaxin®, and Zoraxel™ - all potential best in class therapeutics - and a robust pipeline of preclinical compounds to treat multiple cancers and CNS disorders. Rexahn also operates key R&D programs of nano-medicines, 3D-GOLD, and TIMES drug discovery platforms. For more information, please visit www.rexahn.com.

Safe Harbor

To the extent any statements made in this press release deal with information that is not historical, these are forward-looking statements under the Private Securities Litigation Reform Act of 1995. Such statements include, but are not limited to, statements about Rexahn's plans, objectives, expectations and intentions with respect to future operations and products and other statements identified by words such as "will," "potential," "could," "can," "believe," "intends," "continue," "plans," "expects," "anticipates," "estimates," "may," other words of similar meaning or the use of future dates. Forward-looking statements by their nature address matters that are, to different degrees, uncertain. Uncertainties and risks may cause Rexahn's actual results to be materially different than those expressed in or implied by Rexahn's forward-looking statements. For Rexahn, particular uncertainties and risks include, among others, the difficulty of developing pharmaceutical products, obtaining regulatory and other approvals and achieving market acceptance; the marketing success of Rexahn's licensees or sublicensees; the success of clinical testing; and Rexahn's need for and ability to obtain additional financing. More detailed information on these and additional factors that could affect Rexahn's actual results are described in Rexahn's filings with the Securities and Exchange Commission, including its most recent annual report on Form 10-K and subsequent quarterly reports on Form 10-Q. All forward-looking statements in this news release speak only as of the date of this news release. Rexahn undertakes no obligation to update or revise any forward-looking statement, whether as a result of new information, future events or otherwise.

Rexahn Pharmaceuticals, Inc.
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Stephanie Ascher, 212-362-1200
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or
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Constantine Theodoropulos, 617-401-3116
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Source: Rexahn Pharmaceuticals, Inc.

Released October 3, 2011