Pharmacokinetics of sulfamethoxazole and trimethoprim in mexicans: Bioequivalence of two oral formulations (URO‐TS D® and bactrim F®)

Abstract

Two oral pharmaceutical formulations (URO-TS D and Bactrim F) containing 800 mg of sulfamethoxazole (SMZ) and 160 mg of trimethoprim (TMP) were given to 10 Mexican healthy volunteers, following a randomized cross-over design. Blood and urine samples were obtained, concentrations of TMP, SMZ, and its metabolite N4-acetyl SMZ were measured by HPLC and pharmacokinetic analyses were performed. The observed Cmax, tmax, half-life, AUC, and cumulative urinary excretion values for the three compounds studied were within the ranges that have been previously reported for European and North American subjects. Therefore, it appears that pharmacokinetics of SMZ and TMP in Mexicans are similar to those observed in Caucasian populations. When the two studied formulations were compared, no statistically significant differences were detected in any pharmacokinetic parameter. Therefore, it is concluded that both brands tested are bioequivalent. Moreover, these two formulations manufactured in Mexico yield SMZ and TMP plasma and urine levels similar to those obtained with equivalent formulations of European or North American origin.