Aprindine hydrochloride, a relatively new Class I antiarrhythmic agent, is known for its effectiveness in treating cardiac rhythm disorders, especially in ventricular arrhythmias. We investigated the pharmacokinetic parameters, clinical effects on ventricular premature contractions (VPCs), and minimal effective plasma levels in 29 patients with frequent VPCs after administration of a single 100 to 150 mg oral dose of aprindine. The plasma concentration curve of a single oral dose of aprindine was described best by a two-compartment open model in the majority of patients studied.
The mean value for the maximum plasma level (Cmax) and the time to Cmax (Tmax) were 0.77μg/ml and 2.9 hours, respectively. The mean plasma half-life (T1/2β) was 26.5 hours. The number of VPCs per hour was significantly reduced after admini stration of aprindine for 2 to 11 hours continuously in 24 patients in whom analyzable Holter dynamic ECG recordings were made both before and after drug administration. The drug was judged to be effective according to our clinical evaluating criteria in 14 of the 24 patients (58%), with decreases in the VPC/hr rate of at least 80% shown for 2 or more hours consecutively during the period 2 to 11 hours after administration of aprindine. The mean effective time was 7.8 hours. The minimal effective plasma level was defined as the concentration at the end of the period of effectiveness and ranged from 0.13 to 0.68 μg/ml (mean 0.38 μg/ml).
