Absorption kinetics of procainamide in humans

Area of Science:

• Pharmacokinetics
• Drug Delivery Systems

Background:

• Procainamide hydrochloride is an antiarrhythmic drug.
• Understanding its pharmacokinetic profile is crucial for effective therapeutic use.

Purpose of the Study:

• To compare plasma concentrations of procainamide hydrochloride after intravenous infusion, conventional capsules, and sustained-release tablets.
• To evaluate the bioavailability and absorption characteristics of oral procainamide formulations.

Main Methods:

• 11 healthy male volunteers received 500 mg of procainamide hydrochloride via three routes: intravenous infusion, conventional capsules, and sustained-release tablets.
• Plasma drug concentrations were analyzed.
• Two-compartment open modeling was used for intravenous data.
• First-order absorption kinetics were calculated for oral formulations.

Main Results:

• Intravenous infusion data yielded mean elimination rate constant (Kel) of 0.0162 min-1, and intercompartmental rate constants (k12, k21) of 0.0542 and 0.0233 min-1.
• Oral bioavailability averaged 83% for capsules and 79% for sustained-release tablets.
• Absorption rate constants (ka) were 0.0336 min-1 for capsules and 0.0039 min-1 for sustained-release tablets, indicating first-order absorption.

Conclusions:

• The sustained-release formulation demonstrated delayed drug release.
• Adequate bioavailability was confirmed for the sustained-release procainamide hydrochloride tablet.
• These findings support the potential of sustained-release formulations for procainamide therapy.