Phenytoin-Quinidine Interaction in a Patient with Recurrent Ventricular Tachyarrhythmias

Abstract

To the Editor: Phenytoin and quinidine have been used in combination to treat ventricular ectopy. Phenytoin is known to increase the metabolism of quinidine by inducing hepatic microsomal enzymes.^{1 , 2} In spite of this fact, there are only rare clinical reports of phenytoin-quinidine interactions in the treatment of ventricular arrhythmias.³ Consequently, the primary intent of this report is to highlight the potential complication of malignant ventricular ectopy in a patient receiving both oral phenytoin and quinidine if the drug levels and degree of ectopy are not monitored closely.A 65-year-old white man was admitted to the medical intensivecare unit after . . .