Increase in Plasma Levels of Clozapine and Norclozapine After Administration of Nefazodone

Letter to the Editor

Sir: Drug interactions can adversely affect the treatment of patients taking antipsychotic agents. Therefore, predictability of such interactions would be beneficial in avoiding unnecessary negative effects of drug therapy. However, predictability of drug interactions is not always assured, given the varied pharmacokinetic parameters associated with psychotherapeutic agents. This case report describes a patient in whom concomitant administration of nefazodone resulted in decreased clearance with resultant increase in plasma concentrations of clozapine and norclozapine.