Somaxon Pharmaceuticals Inc. (SOMX) Monday said the FDA has determined that the new drug application for Silenor, which is indicated for the treatment of insomnia, cannot be approved in its present form. Following the news, the company's stock lost more than 50% in the intra-day trading.
In its complete response letter, the FDA stated that the Silenor new drug application, or NDA, did not meet the approval standard for efficacy due to a lack of robustness of sustained subjective sleep maintenance efficacy in adults with primary insomnia. However, the FDA did not raise any clinical safety issues.
The FDA also requested the company to submit an amended Risk Evaluation and Mitigation Strategy, including a Medication Guide to be distributed with the product, in any resubmission of the NDA.
As the complete response letter did not contain any specific requirement to conduct any additional clinical work or other specific guidance to address the issue raised by the FDA, Somaxon believes that a meeting with the FDA will be necessary to discuss the basis for the FDA's decision and to seek such specific guidance. The company intends to schedule this meeting as soon as possible.
Somaxon already received a complete response letter for the Silenor NDA in February 2009, in which the FDA had raised a number of issues relating to the interpretation of the efficacy data.
Though no safety issues were raised, the FDA had asked the company to address the possibility that Silenor may prolong the cardiac QT interval.
In reply to the complete response letter, Somaxon resubmitted its NDA to the FDA for Silenor for the treatment of insomnia on June 4.
The resubmission included additional statistical analyses of the company's clinical data relating to the durability of subjective sleep maintenance efficacy. It also included the results of the company's completed clinical trial of Silenor that evaluated the potential for electrocardiogram, or ECG, effects.
The results of that clinical trial demonstrated that Silenor had no effect on QT interval prolongation when administered at 6 mg or under exaggerated exposure conditions of 50 mg.
According to the American Psychiatric Association, about 70 million adult Americans are affected by insomnia. The insomnia market accounted for more than $2.0 billion in sales in 2008 despite the introduction in April 2007 of generic versions of Sanofi-Aventis' (SNY) Ambien, the market leader at that time.
Somaxon is a development stage company and has not generated any revenue from product sales to date. If approved, Silenor would be the company's first commercial drug. Somaxon estimates peak annual sales for Silenor to exceed $500 million.
Somaxon is currently trading at $1.44, down $2.09 or 59.21% on a volume of 23.22 million shares.
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