Wyeth and Solvay Pharmaceuticals received a “not approvable” letter from the FDA in response to the NDA for bifeprunox, an atypical antipsychotic for the acute treatment of schizophrenia, as well as the maintenance of stable adult patients.

The FDA stated in the letter that bifeprunox demonstrated effectiveness in its long-term maintenance study and indicated that a second positive maintenance study could be sufficient to support a maintenance claim for bifeprunox. The companies will meet with the FDA to discuss study design and to assess how this additional study, combined with ongoing and planned studies, might support a maintenance indication. The Agency also requested further information regarding human metabolism of bifeprunox, and additional information regarding a patient who died while participating in one of the trials.

“We believe that bifeprunox is a promising drug for the treatment of schizophrenia and that there is a need for new treatment options to help people with schizophrenia manage their disease,” says Laurence Downey, M.D., president and chief executive officer of Solvay Pharmaceuticals, Inc. “We will work with the FDA to address its comments and pursue the approval of bifeprunox as soon as possible.”

“The development of bifeprunox offers the possibility of a new treatment approach for patients where maintaining stability is challenged by the metabolic consequences frequently encountered with long-term therapy. We continue to support the development of the compound and the approach,” adds Gary L. Stiles, M.D., executive vice president and chief medical officer, Wyeth Pharmaceuticals.