Comparison of in in vitro Evaluation of Commercially Available Trimethoprim-Sulphamethoxazole Tablets.

Abstract

Five commercial brands of combined formulations of 1:5 Trimethoprim and Sulphamethoxazole were evaluated, in vitro, for their weight variation, the percent labelled amount of active ingredients, hardness, disintegration time and dissolution rate by the official pharmacopoeal methods.  All brands meet the pharmacopoeal requirements with regard to content uniformity; disintegration time and the percentage of Sulphamethoxazole whereas Trimethoprim content was not within the USP range in some commercial formulations.  Variation among different brands was demonstrated by diverse dissolution rates and profiles.  Only brand A and B passed the USP dissolution test and no statistically-significant difference was noted for both Trimethoprim and Sulphamethoxazole.  Based on the previous correlation study between in vitro dissolution and in vivo absorption rate of Trimethoprim, it was recommended that dissolution data could predict the bioavailability of this drug.  It is concluded that only brand A and B passed all major essential requirements of the official compendium and accordingly improvement with respect to dissolution characteristic for others is needed.