Effect of oral mexiletine versus quinidine on premature ventricular complexes

We performed a double-blind, randomized study in investigating the efficacy of mexiletine verus quinidine sulfate in 14 ambulatory patients with an average of at least 30 PVCs per hour for two sequential 24-hour periods of ambulatory monitoring. The double-blind dose of drug was individually titrated for each patient according to efficacy. The mean daily dose of mexiletine was 600 mg in one patient and 900 mg in 5 patients. The mean daily dose of quinidine was 800 mg in 5 patients, 1200 mg in one patient, and 1600 mg in two patients. Adverse effects occurred in three of 8 patients (38%) on quinidine and in 4 of 6 patients (67%) on mexiletine. Two of 8 patients (25%) on quinidine and 4 of 6 patients (67%) on mexiletine had to discontinue the drug because of adverse effects. An average reduction in PVCs of at least 70% during the last two 24-hour recordings on double-blind drug compared with the control period recordings occurred in 4 of 6 patients (67%) on quinidine and in 3 of 6 patients (50%) on mexiletine. Four of 8 patients (50%) on quinidine and one of 6 patients (17%) on mexiletine were able to tolerate the drug and have at least 70% reduction of PVCs.