Efficacy of mexiletine in chronic ventricular arrhythmias compared with quinidine: a single-blind, randomized trial

This single-blind, randomized study was designed to evaluate the efficacy and safety of oral mexiletine compared with oral quinidine in suppressing premature ventricular contractions (PVCs). Fifty-one patients were studied for less than or equal to 12 weeks; 26 patients were randomized to the mexiletine group and 25 to the quinidine group. The drugs were administered in an increasing dose regimen to suppress the PVCs by 70% from the baseline value in both groups. Mexiletine reduced the average number of PVCs by 70% of the baseline number in a comparable fashion to quinidine; 69% in the mexiletine group vs 70% in the quinidine group (p greater than 0.05). There was a comparable reduction (greater than or equal to 50%) of ventricular couplets from the baseline value in the 2 groups, 78% in the mexiletine group vs 86% in the quinidine group (p greater than 0.05). The effect of mexiletine on suppression of ventricular tachycardia was also similar, 72% in the mexiletine group vs 71% in the quinidine group (p greater than 0.05). There was no significant difference in the 2 groups in side effects. This study shows the comparable efficacy and tolerance of mexiletine and quinidine for the control of ventricular arrhythmias in a large number of patients with diverse forms of heart diseases.