Comparison of the antiarrhythmic activity of quinidine and quinine.

A comparison was made between the effects of quinidine and quinine on experimental arrhythmias and on cardiac electrophysiologic parameters. Both drugs raised ventricular fibrillation thresholds, reversed aconitine-induced atrial fibrillation, decreased ouabain-induced abnormal ventricular beats, and increased atrial refractory periods and His-Purkinje conduction time. In contrast, only quinidine antagonized acetylcholine-induced atrial fibrillation. In addition, quinidine increased ventricular fibrillation thresholds and atrial refractory periods for a longer time period than quinine. These observations are discussed in terms of choosing an appropriate model for testing new compounds with suspected quinidine-like activity.