Comparative Efficacy of Moricizine and Quinidine for Benign and Potentially Lethal Ventricular Arrhythmias

Abstract

The relative antiarrhythmic efficacy of moricizine and quinidine in suppressing ventricular arrhythmias in patients with benign or potentially lethal ventricular arrhythmias was examined in a placebo-controlled, doubleblind longitudinal crossover study during a 49-day protocol. Although both drugs significantly reduced total ventricular ectopic beats relative to placebo, moricizine was modestly superior to quinidine in total ventricular ectopic beat depression and also manifested a low incidence of adverse side effects. Using 75% ventricular ectopic beat reduction as the criteria for efficacy, moricizine was effective in 75% of all patients compared with an effectiveness of 60% of patients during quinidine therapy (p < 0.05). Mean trough plasma levels of moricizine and quinidine were unrelated to antiarrhythmic efficacy. Moricizine had no effect on the QT interval whereas quinidine prolonged it significantly. Importantly, while quinidine produced adverse side effects in 63% (17/27) of patients and resulted in early discontinuation of the protocol in 41 % (11/27) of patients, moricizine was well tolerated with only 25% (7/28) of patients having complaints and 14% (4/28) withdrawing early.