60-Patient National Phase I-b Clinical Trial to Begin in 2012

Jersey City, NJ — February 20, 2012 — S1 Pharmaceuticals, Inc. (S1) announced today that it has submitted its Investigational New Drug (IND) application to the U.S. Food and Drug Administration for Phase I-b clinical studies of SIP-104 (Lorexys). Lorexys is the Company’s lead drug candidate for the treatment of Hypoactive Sexual Desire Disorder (HSDD) and Female Sexual Dysfunction (FSD).

Lorexys’ clinical development plan is based on pharmacokinetic and safety data for a 505(b)(2) New Drug Application (NDA). Lorexys is a novel use fixed-dose combination (FDC) in an oral enteric formulation acting on the central nervous system (CNS) with therapeutic characteristics that benefit sufferers of sexual health disorders. It is intended as a treatment for HSDD both as a standalone and as an adjunct to testosterone therapy for the disorder.

“The IND filing for Lorexys is an important milestone for our Company,” stated Nicolas G. Sitchon, Chief Executive Officer. “The Lorexys Clinical Development Program represents S1’s entry into the significant Women’s Sexual Health Disorders field with a lead drug candidate having several potential advantages over other treatment options in development.”

On the condition of FDA endorsement of an approvable Investigational New Drug application for Lorexys, the Company will conduct Multiple Ascending Dose (MAD) safety, tolerability, and exploratory efficacy Phase I-b studies on Lorexys in 2012. Upon successful completion, the results from these studies will satisfy FDA requirements to commence Phase II studies for HSDD patients.