Comparative bioavailability of two oral sustained-release procainamide products

Area of Science:

• Pharmacology
• Clinical Pharmacy
• Cardiovascular Medicine

Background:

• Sustained-release oral procainamide formulations are used to manage arrhythmias.
• Comparing the bioavailability of different sustained-release formulations is crucial for therapeutic equivalence.
• Procan SR and Pronestyl-SR are two such oral procainamide preparations.

Purpose of the Study:

• To compare the bioavailability characteristics of Procan SR and Pronestyl-SR.
• To assess key pharmacokinetic parameters including AUC, Cmax, Cmin, Cmax:Cmin ratio, and tmax.
• To determine if these two sustained-release procainamide formulations exhibit similar drug release profiles.

Main Methods:

• A randomized crossover study involving 10 patients with arrhythmias.
• Patients received Procan SR 1g and Pronestyl-SR 1g orally every six hours for 48 hours each.
• Serum procainamide concentrations were measured to determine pharmacokinetic parameters at steady-state.

Main Results:

• Mean time to maximum serum drug concentration (tmax) was significantly different between Procan SR (2.2 +/- 0.8 hours) and Pronestyl-SR (3.8 +/- 1.1 hours).
• No statistically significant differences were found in area under the curve (AUC), maximum concentration (Cmax), or minimum concentration (Cmin).
• The study had adequate power to detect differences in AUC, Cmax, and Cmin, but not tmax.

Conclusions:

• Procan SR and Pronestyl-SR likely possess similar therapeutic properties when administered at the same dosage and schedule.
• The observed difference in tmax suggests variations in drug release rates between the two formulations.
• Larger population studies are needed to confirm bioavailability and project data to the general population.