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Drs. Puzantian and Shaw Reply

J Clin Psychiatry 1997;58(8):365 [letter]

Letter to the Editor

Sir: Dr. Yong’s comments regarding our letter raise the interesting issue of the potential for an interaction between nefazodone and risperidone via inhibition of the cytochrome P450 2D6 isoenzyme, leading to increased levels of risperidone. Interaction studies of nefazodone with the triazolobenzodiazepines triazolam and alprazolam, both metabolized by cytochrome P450 3A4, have revealed substantial and clinically significant increases in plasma triazolobenzodiazepine concentrations. Only the benzodiazepines metabolized by the 3A4 isoenzyme have a potential interaction with nefazodone.2,3