Pirmenol for control of ventricular arrhythmias: oral dose-ranging and short-term maintenance study.

The antiarrhythmic efficacy and safety of oral pirmenol hydrochloride were assessed during a controlled, dose-ranging and short-term maintenance study in 12 patients with frequent (greater than 480/8 hours) premature ventricular complexes (PVCs). Eleven patients (92%) responded favorably (greater than 70% PVC suppression) to a trial of different doses. Mean interval (8-hour) suppression of PVC frequency was 95% in these 11 and 86% in the entire group. Twenty-four-hour suppression was similar in responders (88%). Repetitive PVCs were essentially eliminated. The mean effective dose was 316 mg/day (105 mg/8 hours). The average predose (trough) plasma concentration at the end of dose ranging was 1.4 micrograms/ml and the drug elimination half-life 7.3 hours (n = 12). Of 11 responding patients, 10 completed a 2-week outpatient trial. Pirmenol continued to be effective and tolerated in 8 patients, maintaining an overall average outpatient PVC suppression of 80%. The electrocardiographic intervals were mildly prolonged after multiple dosing (PR + 7%, QRS + 12%, QTc + 8%; all p less than 0.01). Blood pressure and heart rate did not change during treatment. The echocardiographic ejection fraction was maintained. Thus, oral pirmenol appears to be effective, conveniently administered and well tolerated as an antiarrhythmic agent for control of ventricular extrasystoles.