Suppression of premature ventricular contractions by acebutolol

The antiarrhythmic action of the beta-blocking drug, acebutolol, was evaluated in patients with frequent premature ventricular contractions (PVCs). In the 12 hours following administration of a single 300 mg oral dose, 8 of 10 patients showed a greater than 50% reduction in PVC frequency, and statistical analysis indicated that PVC reduction persisted for 10 hours after the single dose. Analysis of plasma concentrations of acebutolol and an acetyl metabolite indicated that after single oral doses of plasma concentrations of the metabolite exceed those of unchanged acebutolol. When patients were studied during periods of 300 mg doses every 8 hours, eight of 11 showed a 70% reduction in PVC frequency, and analysis showed that the therapeutic effect was present throughout the 24-hour monitoring period. Acebutolol slowed the heart rate and prolonged the PR interval without affecting the QT interval. Significant clinical or laboratory toxicity was not encountered. In the small group studied, acebutolol was found to be safe and effective for short-term administration to patients with frequent PVCs and possessed a relatively long duration of antiarrhythmic action.