Pharmacokinetics of procainamide intravenously and orally as conventional and slow-release tablets.
Pharmacokinetics of procainamide were studied in healthy volunteers after single doses intravenously and orally as conventional and slow-release tablets and after repeated oral doses to steady state. The initial distribution after intravenous administration was rapid and the overall elimination in the beta-phase corresponded to t1/2 of 2.7 hr. The mean volume of the central compartment was small and only 4 percent of V-d (beta), which was 2.3 l/kg body weight. About 65 percent was excreted unchanged after intravenous administration and about 55 percent after a single oral dose of 500 mg. The recovery of the metabolite N-acetylprocainamide was 12 percent after both routes of administration. Procainamide was completely absorbed from the gastrointestinal tract and the first-pass elimination was very limited. The rates of absorption from the tablet compositions were well correlated to the in vitro dissolution properties. Administration of slow-release tablets every 8 hr gave about the same mean plasma level at steady state as ordinary tablets given every 4 hr, and the availability was the same from both preparations. The occasional high plasma concentration peaks after ordinary tablets were not observed after the slow-release tablets. Renal clearance was about 500 ml/min, indicating an active secretion in the tubules.
D000107:Acetylation; D000284:Administration, Oral; D000328:Adult; D001702:Biopharmaceutics; D003692:Delayed-Action Preparations; D006801:Humans; D007275:Injections, Intravenous; D007700:Kinetics; D008297:Male; D011342:Procainamide / Q000008:administration & dosage / Q000378:metabolism*; D013607:Tablets
D003692:Delayed-Action Preparations; D013607:Tablets; D011342:Procainamide