Cardiac Antiarrhythmic Effect of Imipramine Hydrochloride

Abstract

Over 20 million prescriptions are written annually for tricyclic antidepressants.¹ The cardiotoxicity of overdosage is well documented,^{2 3 4 5} but little is known about cardiac effects of therapeutic plasma concentrations.^{4 , 6 , 7} The toxic effects of tricyclic antidepressants on cardiac conduction suggest quinidine-like activity.^{2 , 6} We postulated that these drugs also might have quinidine-like antiarrhythmic properties in therapeutic concentrations. We tested this hypothesis in two patients treated for mental depression with imipramine (Tofranil) who also had atrial and ventricular premature depolarizations. We found that antidepressant concentrations of imipramine had quinidine-like effects on the electrocardiogram and antiarrhythmic effects on both atrial and ventricular arrhythmias.MethodsTwo . . .