Comparative bioavailability of 4 amoxicillin formulations in healthy humanvolunteers after a single dose administration

Objective: To compare the bioavailability of two amoxicillin oral suspensio n (250 mg/5 ml) formulations and two amoxicillin capsule (500 mg) formulati ons (Amoxicilina from Medley S/A Industria Farmaceutica, Brazil, as test fo rmulations and Amoxil from SmithKline Beecham Laboratorios Ltda., Brazil, a s reference formulations) in 48 volunteers of both sexes. Material and meth ods: The study was conducted open with a randomized two-period crossover de sign and a one-week washout period. Plasma samples were obtained over a 12- hour interval. Amoxicillin concentrations were analyzed by combined reverse d phase liquid chromatography and tandem mass spectrometry (LC-MS-MS) with positive ion electrospray ionization using the selected ion monitoring meth od. From the amoxicillin plasma concentration vs. time curves the following pharmacokinetic parameters were obtained: AUC(last), AUC(0-infinity) and C -max. Results: Geometric mean of Amoxicilina/Amoxil 250 mg/5 ml individual percent ratio was 103.70% for AUC(last), 103.15% for AUC(0-infinity) and 10 6.79% for C-max. The 90% confidence intervals were 97.82 - 109.94%, 97.40 t o 109.24%, and 96.38 - 118.33%, respectively. Geometric mean of Amoxicilina /Amoxil 500 mg capsule individual percent ratio was 93.26% for AUC(last), 9 3.27% for AUC(0-infinity). and 90.74% for C-max. The 90% confidence interva ls were 85.0 - 102.33%, 85.12 - 102.31%, and 80.14 - 102.73%, respectively. Conclusion: Since the 90% CI for both C-max, AUC(last) and AUC(0-infinity) were within the 80 - 125% interval proposed by the Food and Drug Administr ation, it was concluded that Amoxicilina 250 mg/5 nil oral suspension and A moxicilina 500 mg capsule were bioequivalent to Amoxil 250 mg/5 ml oral sus pension and to Amoxil capsule 500 mg, respectively, with regard to both the rate and extent of absorption.