Effect of age, gender, and race on steady state procainamide pharmacokinetics after administration of procanbid sustained-release tablets.

Procainamide hydrochloride is a Class 1A antiarrhythmic agent administered intravenously or orally for treatment of symptomatic ventricular premature depolarizations (VPD), nonsustained ventricular tachycardia, and life-threatening ventricular arrhythmias. A new sustained-release formulation, Procanbid, which allows for twice-daily dosing was recently approved for marketing in the United States. This paper describes the population pharmacokinetics of procainamide and N-acetylprocainamide (NAPA), the major metabolite, in healthy volunteers and patients with VPD by combining Cmax, tmax, Cmin, and AUC(0-12) values at steady state from six multiple-dose studies in which one 1000-mg or two 500-mg Procanbid tablets were administered. Means of parameters by race and gender were inspected for trends likely to be of clinical relevance. Procainamide and NAPA pharmacokinetic parameters observed after administration of Procanbid tablets were similar in blacks and whites, and in men and women. However, differences in body size should be considered when determining the Procanbid dose for women. Participant age had significant impact on NAPA pharmacokinetics in this study population and should be considered in dose selection. Age effects on procainamide were not detected in the study population, which was heavily weighted toward younger subjects, but are anticipated in the older population of patients for which procainamide is indicated. Procanbid formulation performance was not altered by patient demographics.