Somaxon Pharmaceuticals, Inc, a specialty pharmaceutical company focused on the in-licensing, development and commercialization of proprietary product candidates for the treatment of diseases and disorders in the central nervous system therapeutic area, has received a Complete Response Letter from the US Food and Drug Administration (FDA) for its New Drug Application (NDA) for Silenor (doxepin) for the treatment of insomnia. Based on its review, the FDA has determined that the NDA cannot be approved in its present form.

In the Complete Response Letter the FDA raised a number of issues relating to the interpretation of the efficacy data contained in the Silenor NDA and indicated that the FDA was open to a discussion of these concerns. The FDA did not specifically request the company to conduct additional clinical trials of Silenor. The company believes that a discussion with the FDA will be necessary to gain a complete understanding of the implications of the issues raised in the Complete Response Letter, and the company intends to schedule this discussion as soon as possible.

With respect to safety, the FDA noted that there were no adverse events observed in the clinical studies included in the NDA that would preclude approval, but asked the company to address the possibility that doxepin may prolong the cardiac QT interval. The company intends to respond by submitting to the FDA the results of its completed clinical trial of doxepin that evaluated the potential for electrocardiogram effects. As the company has previously disclosed, the results of this clinical trial demonstrated that doxepin had no effect on QT interval prolongation when administered at 6 mg or 50 mg.

"We continue to believe that the data in the NDA we have submitted, together with the QT data we will submit, is sufficient to support a determination by the FDA that Silenor can be approved for the treatment of insomnia," said Richard W Pascoe, Somaxon's president and chief executive officer. "We are committed to working with the FDA to resolve the issues raised in the Complete Response Letter so that Silenor can be approved. As we continue to seek approval of Silenor, we will continue to take measures to conserve our cash and will evaluate financing alternatives available to us."

Silenor is a low-dose (1 mg, 3 mg, 6 mg) oral tablet formulation of doxepin hydrochloride that is patent protected for use in insomnia.