Long−term Usefulness of Aprindine Hydrochloride in Elderly Patients

Background Aprindine is a Vaughan−Williams Class Ib antiarrhythmic drug with a weaknegative inotropic effect. It is unnecessary to adjust its dose even in patients with renalimpairment because it is metabolized in the liver, suggesting its usefulness in elderlypatients. However, few reports are available on its safety and blood concentration duringlong−term treatment in elderly patients.Objectives This study conducted on elderly patients with tachyarrhythmia who weretreated with aprindine for a long time period and investigated aprindine concentration inblood and its effect on cardiac function.Methods Thirty outpatients with symptomatic supraventricular or ventricular arrhythmiawere enrolled. Aprindine was administered at 40 mg／day b. i. d. Blood concentration wasmeasured before and 2 hours after morning medication at 6 months.Results Of the study population, 8 patients were withdrawn from the study. In the remaining22 patients, aprindine concentrations in blood were measured at 218±115 days（max. 504days；before morning medication）and 213±135 days（max. 518 days；2 hours after morningmedication）. The time course of aprindine concentration in blood was stable. No significantdifference in the blood concentration was found between the elderly（≧65 years of age）andnon−elderly （＜65 years） patients, which suggested that aging had no influence on theincreased aprindine level in blood concentration. Among the 14 patients with paroxysmalatrial fibrillation, 13 patients maintained sinus rhythm during the treatment. Twenty−fourhourECG monitoring showed that aprindine significantly reduced supraventricular and ventricularpremature contractions without any influence on heart rates.Conclusions The number of elderly patients with arrhythmias is increasing in an agingsociety. Aprindine can be safely administered to such patients receiving long−term treatment.（Jpn Pharmacol Ther 2010；38：165−71）KEY WORDS Aprindine, Elderly patient, Long−term, Concentrations