Somaxon Pharmaceuticals Says May Delay Approval Submission for Sleep Drug SAN DIEGO -- Somaxon Pharmaceuticals, Inc. today provided an update on its non-clinical program for SILENOR(TM) (doxepin HCl), its lead product candidate that has completed a successful Phase 3 clinical program for the treatment of insomnia. On May 8, 2007, Somaxon received correspondence from the U.S. Food and Drug Administration (FDA) in which the FDA stated that the results of the company's ongoing 26-week transgenic mouse carcinogenicity study of SILENOR(TM) should be included as part of the initial New Drug Application (NDA) submission for SILENOR(TM). This request may result in the company delaying its initial NDA submission until the first quarter of 2008. Somaxon continues to plan to conduct the standard two-year carcinogenicity study and to submit the results of this study as a post-NDA approval commitment. Ken Cohen, Somaxon's President and CEO, said, "Our assumption based on previous FDA correspondence was that we could file our NDA without this transgenic mouse carcinogenicity data and provide this data during the NDA review process. While our NDA preparation activities continue as planned, we intend to discuss this latest communication with the FDA." As previously disclosed, based on a request Somaxon received from the FDA in May 2006, the company initiated a preclinical program for SILENOR(TM) consisting of standard genotoxicity, reproductive toxicology and carcinogenicity studies. The FDA indicated that the data from the genotoxicity studies and reproductive toxicology studies should be included in the NDA for SILENOR(TM). The FDA also indicated that depending on the outcome of the genotoxicity studies, it may be flexible as to the timing of the conduct of the carcinogenicity studies, including the potential that the data from those studies may be submitted as a post-NDA approval commitment. In September 2006, Somaxon completed the genotoxicity studies and submitted the results to the FDA. No signal indicative of genotoxicity was found in any of the assays. In February 2007, the FDA agreed with the company's assessment that SILENOR(TM) does not appear to have genotoxic potential. The FDA indicated that, unless other preclinical data raise a concern, a complete assessment of the carcinogenic potential of SILENOR(TM) may not be needed prior to NDA approval. The FDA also indicated that it may accept the results of a shorter-term carcinogenicity study for approval of the NDA and allow the standard two-year carcinogenicity study to be completed as a post-NDA approval commitment. The reproductive toxicology studies are ongoing, and Somaxon expects to complete them in the first half of 2007. The 26-week transgenic mouse carcinogenicity study has been initiated. The company is also conducting dose range finding studies in preparation for a standard two-year carcinogenicity study. About Somaxon Pharmaceuticals, Inc. Headquartered in San Diego, CA, Somaxon Pharmaceuticals, Inc. is a specialty pharmaceutical company focused on the in-licensing and development of proprietary product candidates for the treatment of diseases and disorders in the fields of psychiatry and neurology. Somaxon has completed four successful Phase 3 clinical trials for its lead product candidate, SILENOR(TM) (doxepin HCl) for the treatment of insomnia. The company has also completed a pilot Phase 2 trial for nalmefene in smoking cessation with positive results. It has also completed a Phase 2/3 clinical trial for nalmefene for the treatment of pathological gambling that did not achieve statistical significance for the primary or secondary endpoints. The company will evaluate the results from both of these trials before making determinations regarding the future of the nalmefene program. Acamprosate Ca, a potential treatment for movement disorders, is currently in formulation development. For more information, please visit the company's web site at www.somaxon.com. Somaxon cautions you that statements included in this press release that are not a description of historical facts are forward-looking statements. For example, statements regarding the FDA's requirements relating to Somaxon's preclinical studies, the planned filing of an NDA for SILENOR(TM) and the potential for post-approval carcinogenicity studies are forward looking statements. The inclusion of forward-looking statements should not be regarded as a representation by Somaxon that any of its plans will be achieved. Actual results may differ materially from those set forth in this release due to the risks and uncertainties inherent in Somaxon's business, including, without limitation, the timing of receipt of preclinical study results and any NDA submission; the potential for the FDA to require preclinical or clinical requirements to support an NDA filing for SILENOR(TM), or the imposition of additional requirements to be completed before or after regulatory approval; Somaxon's ability to demonstrate to the satisfaction of the FDA that potential NDA approval of SILENOR(TM) is appropriate without standard, long-term carcinogenicity studies, given the context of completed trials and pending studies; the potential for SILENOR(TM) to receive regulatory approval for one or more indications on a timely basis or at all; the results of pending preclinical studies for SILENOR(TM); unexpected findings relating to SILENOR(TM) that could delay or prevent regulatory approval or commercialization, or that could result in recalls or product liability claims; other difficulties or delays in development, testing, manufacturing and marketing of and obtaining regulatory approval for SILENOR(TM); the potential to enter into and the terms of any strategic transaction; the scope and validity of patent protection for SILENOR(TM); the market potential for insomnia, and Somaxon's ability to compete; Somaxon's ability to raise sufficient capital; and other risks detailed in Somaxon's prior press releases as well as in periodic filings with the Securities and Exchange Commission. You are cautioned not to place undue reliance on these forward-looking statements, which speak only as of the date hereof. All forward-looking statements are qualified in their entirety by this cautionary statement and Somaxon undertakes no obligation to revise or update this news release to reflect events or circumstances after the date hereof. This caution is made under the safe harbor provisions of Section 21E of the Securities Exchange Act of 1934.