New Animal Study of Rexahn's Serdaxin(TM) Shows Drug's Promise to Treat Anxiety and Depression with Minimal Side Effects

Researchers reveal that Serdaxin has unique therapeutic activity unlike commonly prescribed anti-anxiety drugs

ROCKVILLE, Md.--(BUSINESS WIRE)-- Rexahn Pharmaceuticals, Inc. (NYSE Amex: RNN), today announced the results of a wide-ranging animal study offering more evidence that Serdaxin(TM) may be an effective therapeutic for the treatment of anxiety disorders in humans. Serdaxin is Rexahn's leading anxiety and depression drug candidate, and is currently in Phase II clinical trials.

The research tested Clavulanic acid, the primary compound in Serdaxin, across three mammalian species - hamsters, rats and cotton top tamarin monkeys - and was carried out at the University of Massachusetts and the University of Wisconsin. Results of the study reveal that Clavulanic acid is highly potent, has a unique profile, and has anti-anxiety "activity unlike any of the commonly prescribed drugs used to treat anxiety disorders."

The study (to be published in the journal of Pharmacology, Biochemistry and Behavior in the August 2009 issue) "Clavulanic acid: A competitive inhibitor of beta-lactamases with novel anxiolytic-like activity and minimal side effects " found that Serdaxin exerts strong anti-anxiety and anti-depression effects in all three animal species at low doses and without unwanted side effects.

Of particular interest, when the study compared Serdaxin to commonly prescribed psychoactive drugs (benzodiazepines), is that Serdaxin was found to have an extremely favorable profile. For example, Serdaxin was able to provide the desired anti-anxiety and anti-depression effects without impaired motor activity and loss in learning and memory. Moreover, Serdaxin was able to achieve its desired efficacy at doses as low as 1/100^th of conventional psychoactive drugs.

"This wide-ranging study offers further evidence that Serdaxin holds the promise to change the treatment paradigm for anxiety and depression," said Dr. Chang H. Ahn, Chairman and CEO of Rexahn. "Conventional psychoactive drugs have slow onset of activity and major unwanted side effects, such as loss in memory, impaired motor activity, weight gain or lack of libido. Due to Serdaxin's unique mechanism of action on the brain, it has the potential to become the first therapeutic capable of treating anxiety and depression without causing these negative side effects."

About Serdaxin

Serdaxin^TM is a potential market leading CNS neuroprotective agent and antidepressant. Among lead indications, we are investigating Serdaxin for depression in Phase II clinical trials. Serdaxin may achieve greater and broader therapeutic coverage, and appears to have no serious side effects such as nausea, vomiting, insomnia, weight gain, sexual dysfunction, cognitive deficit or motor impairment that are linked to existing antidepressant drugs. Serdaxin has well-established and excellent human safety. In preclinical studies, Serdaxin had onset of action in less than two days, whereas currently marketed drugs take several weeks. Based on its novel mechanism affecting both depression and neuroprotection, Serdaxin is a potential treatment for multiple CNS disorders such as Parkinson's disease (PD) and Alzheimer's disease, where the patients suffer from neurodegeneration, and depression as a co-morbidity. Rexahn has multiple clinical programs planned for Serdaxin including depression and anxiety disorders, Parkinson's disease, Alzheimer's and neurodegenerative illnesses, neuroprotection and biodefense uses.

About Rexahn Pharmaceuticals, Inc.

Rexahn Pharmaceuticals is a clinical stage pharmaceutical company dedicated to commercializing first in class and market leading therapeutics for cancer, CNS disorders, sexual dysfunction and other unmet medical needs. For more information please visit www.rexahn.com

Safe Harbor

This press release contains forward-looking statements. Rexahn's actual results may differ materially from anticipated results, and expectations expressed in these forward-looking statements, as a result of certain risks and uncertainties, including Rexahn's lack of profitability, and the need for additional capital to operate its business to develop its product candidates; the risk that Rexahn's development efforts relating to its product candidates may not be successful; the possibility of being unable to obtain regulatory approval of Rexahn's product candidates; the risk that the results of clinical trials may not be completed on time or support Rexahn's claims; demand for and market acceptance of Rexahn's drug candidates; Rexahn's reliance on third party researchers and manufacturers to develop its product candidates; Rexahn's ability to develop and obtain protection of its intellectual property; and other risk factors set forth from time to time in our filings with the Securities and Exchange Commission. Rexahn assumes no obligation to update these forward-looking statements.

    Source: Rexahn Pharmaceuticals, Inc.

Released June 15, 2009