Bioequivalence study of two commercial amoxicillin suspension formulations in healthy human volunteers

To compare the pharmacokinetic profiles and to evaluate the bioequivalence of two commercial amoxicillin suspension formulations (500 mg/5 mL AMOXIL®, reference formulation and AMOXI-PED®, test formulation) in healthy Brazilian volunteers. Under fasting condition, 25 volunteers (13 males and 12 females) were included in this randomized, open-label, two-period crossover (1-week washout interval) bioequivalence study. Blood samples were collected at pre-dose (0 hour) and 0.5, 1, 1.33, 1.66, 2, 2.5, 3, 4, 6, 8, and 12 hours after drug ingestion. Pharmacokinetic parameters (Cmax, tmax, t1/2, AUC0-tlast, and AUC0-∞) were calculated from plasma concentrations for both formulations in each subject. Arithmetic mean values of the pharmacokinetic parameters were: Cmax = 12.004 (± 2.824) μg×mL-1; tmax = 1.118 (± 0.396) h; t1/2 = 1.226 (± 0.179) h; AUC0-tlast = 29.297 (± 6.007) μg×h×mL-1; and AUC0-∞ = 29.299 (± 6.007) μg×h×mL-1 for reference formulation and Cmax = 11.456 (± 2.825) μg×mL-1; tmax = 1.331 (± 0.509) h; t1/2 = 1.141 (± 0.133) h; AUC0-tlast = 28.672 (± 5.778) μg×h×mL-1; and AUC0-∞ = 28.693 (± 5.796) μg×h×mL-1 for test formulation. The confidence intervals (90% CI) for reference and test formulations were, respectively, 90.74 - 100.46% for Cmax and 93.62 - 103.61% for AUC0-t. Based on the results, both formulations of amoxicillin evaluated in this study were considered bioequivalent according to FDA and ANVISA/Brazil criteria.