Moricizine: pharmacodynamic, pharmacokinetic, and therapeutic profile of a new antiarrhythmic.

Moricizine (Ethmozine) is a phenothiazine derivative recently approved in the United States for the treatment of malignant ventricular arrhythmias. Moricizine closely resembles group IA antiarrhythmic agents in the intensity of its effect on the sodium channel, but it differs from the IA subclass in that it shortens the action potential duration in ventricular tissue. Moricizine suppresses frequent ventricular premature depolarizations and nonsustained ventricular tachycardia in 60% to 70% of patients, and it suppresses induced ventricular tachycardia in 15% to 25% of patients. It is well tolerated, with a low incidence of adverse effects. The suggested dosage is 600 to 900 mg per day in three divided doses. Treatment of arrhythmias with prognostic significance should be initiated in the hospital, and monitored with electrophysiologic studies. Additional clinical experience is needed to better define moricizine's role in antiarrhythmic therapy.