Blood Clozapine Levels Elevated by Fluvoxamine: Potential for Side Effects and Lower Clozapine Dosage

Article AbstractLetter to the Editor Sir: We report a case in which very high blood clozapine levels occurred during concomitant use of fluvoxamine. Previous reports have indicated that close monitoring should be done when these two medications are coprescribed because of fluvoxamine's ability to inhibit hepatic microsomal enzymes that metabolize clozapine. However, on the basis of this case and the microsomal enzyme profiles of these two medications, we believe that extreme caution is warranted.