A relative bioavailability study of 500 mg calcium p-aminosalicylate film coating tablet in healthy individuals

The purpose of this study is to evaluate the only available calcium p-aminosalicylate (Ca PAS) commercial product, which is one of the most commonly prescribed non-surveillance products from the Bureau of National Health Insurance (BNHI) database in Taiwan. An open-randomized, balanced, two-way crossover study was designed to evaluate the relative bioavailability (F) of a 500 mg Ca PAS F.C. tablet with a 500 mg Ca PAS suspension in 13 healthy individuals. Blood samples were collected according to a planned time schedule. The plasma concentrations of PAS were measured by a validated liquid chromatography coupled with tandem mass spectrometry (LC/MS/MS) method. Pharmacokinetic parameters of area under the plasma concentration-time curve from the time zero to the time of last quantifiable concentration (AUC0–t), area under the plasma concentration-time curve from time zero to infinity (AUC0–∞), maximum plasma concentration (Cmax), time to reach measured maximum plasma concentration (Tmax), elimination half-life (T1/2), and mean residence time (MRT) were determined by non-compartment methods. F was calculated by [AUC0–∞] of the test drug divided by [AUC0–∞] of the reference drug. The mean geometric ratios of pharmacokinetic parameters, including AUC0–t, AUC0–∞, and Cmax obtained were 0.873, 0.874, and 0.569, respectively. The 90% confidence intervals of ln (AUC0–t), ln (AUC0–∞), and ln (Cmax) after being back natural log-transformed were (74.0–103.0%), (74.1–103.0%), and (38.4–84.3%), respectively. The relative bioavailability of the Ca PAS tablet was 87.4%.