Rexahn Pharmaceuticals, Inc. (NYSE Amex: RNN), a clinical stage pharmaceutical company developing and commercializing potential best in class oncology and CNS therapeutics, today announced that it has enrolled two-thirds of the total patients needed for its Phase IIb clinical trial to study the safety and efficacy of Serdaxin ® to treat major depressive disorder (MDD). The Company began enrollment in January 2011 and plans to enroll a total of 300 patients. The trial is being conducted at 40 sites in the United States. "Serdaxin’s Phase IIb clinical trial enrollment is on schedule, and we are on track to report preliminary results by the end of this year," said Rick Soni, President of Rexahn. The Serdaxin Phase IIb clinical trial is designed as a randomized, double blind, placebo-controlled study with three treatment arms. The primary endpoint is the change from baseline on the Montgomery-Asberg Depression Rating Scale ("MADRS"). About Serdaxin ® Serdaxin ® is a potential market-leading CNS neuroprotective agent and antidepressant. Rexahn is currently investigating Serdaxin as a treatment for depression, in a large Phase II clinical trial. Serdaxin may achieve greater and broader therapeutic coverage and appears to be safe and well tolerated without the appearance of serious side effects that are commonly linked to currently marketed antidepressant drugs, such as selective serotonin uptake inhibitors (SSRI), serotonin-norepinephrine reuptake inhibitors (SNRI), and tricyclic antidepressants (TCA). Serdaxin has a well-established, excellent human safety profile. In preclinical studies, Serdaxin had onset of action in less than two days. Based on its novel mechanism as a dual serotonin and dopamine enhancer, it is a potential treatment for multiple CNS disorders where these neurotransmitters are depleted or implicated in CNS-based illnesses, such as Parkinson’s disease (PD). Serdaxin has the potential to address both non-motor and motor events of PD by serving as a neuroprotective agent and addressing loss of dopaminergic neurons that lead to loss of control of movements; and further, enhancing serotonin and dopamine levels that are involved in depression and mood disorders. Rexahn has multiple clinical programs planned for investigating Serdaxin in the treatment of anxiety disorders, Parkinson’s disease, Alzheimer’s disease and neurodegenerative illnesses, neuroprotection and biodefense uses.