Antiarrhythmic effects of the class 1c antiarrhythmic drug, flecainide, on canine ventricular arrhythmia models

The properties of a class 1c antiarrhythmic drug, flecainide, were examined using 3 canine ventricular arrhythmia models: (1) digitalis-, (2) adrenaline- and (3) two-stage coronary ligation-induced arrhythmias. The minimum effective plasma concentration of flecainide was determined for each model. Flecainide suppressed the arrhythmias. The minimum effective plasma concentrations for arrhythmias induced by digitalis, adrenaline and 24 hr coronary ligation, were 0.9 +/- 0.2, 1.4 +/- 0.6, 1.5 +/- 0.4 mcg/ml, respectively (mean +/- SD, n = 6). These minimum effective plasma concentrations of flecainide were almost equal to the reported in vitro concentration that suppress the Na channels of isolated canine ventricular tissues. Thus, flecainide may suppress these arrhythmias by inhibiting the Na channels of cardiac cells.