The FDA stated in an action letter that the efficacy data, when compared to reference drugs, were not sufficient for approval.
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.
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 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,” said Gary Stiles, executive vice president and chief medical officer of Wyeth Pharmaceuticals.
Bifeprunox, a partial dopamine agonist designed to normalize levels of chemical activity in the brain, has been studied in approximately 2,650 patients with schizophrenia at more than 200 Phase II and 3 clinical trial sites in the US and throughout the world.