Comparative bioavailability of 875 mg amoxicillin tablets in healthy human volunteers.

OBJECTIVE: To compare the bioavailability of amoxicillin 875 mg tablets (EMS Sigma Pharma used as test formulation) and Amoxil BD 875 mg tablets (GlaxoSmithKline used as reference formulation) in 26 healthy volunteers. MATERIAL AND METHODS: 26 healthy volunteers (13 males and 13 females) received each formulation in an open, 2 x 2 crossover, randomized study with seven days of washout period between doses. Plasma samples were obtained over a 12-hour interval after administration. Plasmatic amoxicillin concentrations were obtained by combined reversed-phase liquid chromatography and mass spectrometry with positive ion electrospray ionization using the select ion monitoring method. AUC was calculated by the trapezoidal rule extrapolation method. Cmax and tmax were compiled from the plasmatic concentration-time data. Analysis of variance was carried out using logarithmically transformed AUC0-inf, AUC0-12 h, Cmax and untransformed tmax. RESULTS: The mean values (+/- SD) for AUC0-12 h (microg x h x ml(-1)), AUC0-inf (microg x h x ml(-1)), Cmax (microg x ml(-1)), t1/2 (h) and tmax (h), were, respectively: 55.42 (+/- 16.85), 55.42 (+/- 16.85), 18.59 (+/- 6.3), 1.49 (+/- 1.57) and 2.04 (+/- 0.75) concerning the test formulation, and 51.11 (+/- 18.9), 51.29 (+/- 19.12), 17.83 (+/- 5.86), 1.52 (+/- 1.31) and 2.02 (+/- 0.87) concerning the reference formulation. Confidence intervals (90%) of amoxicillin means of AUC0-12 h and Cmax ratios (test/reference) were: 0.961-1.149 and 0.914-1.142, respectively, agreeing with the bioequivalence criteria established by the Brazilian National Health Surveillance Agency. CONCLUSION: Both formulations were bioequivalent based on both the rate and extent of absorption.