title: Pharmacokinetics of procainamide and N-acetylprocainamide in rats.
abstract: The pharmacokinetics of distribution and elimination of procainamide and its major metabolite, N-actylprocainamide, were studied in rats. Eight rats were selected randomly, and each received intravenously 14C-labeled procainamide hydrochloride (75 mg/kg) or 14C-labeled N-acetylprocainamide hydrochloride (86 mg/kg) according to a two-way crossover design. Serial blood samples were withdrawn for 8 hr, and cumulative urine and feces were collected for 48 hr. The plasma concentration-time relationships of procainamide and N-acetylprocainamide were characterized by one- and two-compartment open models, respectively. A pseudo-three-compartment model was necessary to characterize the time course of N-acetylprocainamide in plasma formed after administration of procainamide. The biological half-lives of procainamide and N-acetylprocainamide averaged 0.66 and 2.1 hr, respectively. The urinary excretion profiles of these drugs and the ratio of their biological half-lives in rats were similar to those in humans.
mesh_terms: D000120:Acecainide / Q000378:metabolism*; D000818:Animals; D006207:Half-Life; D007700:Kinetics; D008297:Male; D008954:Models, Biological; D011342:Procainamide / Q000031:analogs & derivatives* / Q000378:metabolism*; D051381:Rats
chemical_list: D000120:Acecainide; D011342:Procainamide