Bifeprunox has a novel mechanism of action. Conventional antipsychotics are classed into typical and atypical. The typical antipsychotics, such as chlorpromazine and haloperidol, are potent D2receptor antagonists. The atypical antipsychotics started with clozapine, these are classified as multireceptor interacting compounds, acting as an agonist towards 5-HT1A and an antagonist towards D2 receptors among other 5-HT and DA receptors. Bifeprunox and other novel atypical antipsychotics will instead of antagonizing D2 receptors, will act as partial agonists, as well as partial agonists towards 5-HT1A receptors.
In a multi-center, placebo-controlled study, 20 mg of bifeprunox was found to be significantly more effective than placebo at reducing symptoms of schizophrenia, with a low incidence of side effects.
An NDA for Bifeprunox was filed with the U.S. Food and Drug Administration in January 2007. The FDA rejected the application in August 2007. In June 2009, Solvay and Lundbeck decided to cease development because "efficacy data did not support pursuing the existing development strategy of stabilisation of non-acute patients with schizophrenia."
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^Casey DE, Sands EE, Heisterberg J, Yang HM (October 2008). "Efficacy and safety of bifeprunox in patients with an acute exacerbation of schizophrenia: results from a randomized, double-blind, placebo-controlled, multicenter, dose-finding study". Psychopharmacology (Berl.)200 (3): 317–31. doi:10.1007/s00213-008-1207-7. PMID18597078.