Formulating and evaluating the release kinetics of metformin hydrochloride 750 mg extended release tablet prepared by hydrophilic matrix

Abstract

The present study aims to formulate metformin hydrochloride 750 mg extended release tablets based on the hydrophilic matrix which have the amount of drug release equivalent to reference tablets Glucophage XR 750 according to the USP 40 standard and to determine the mechanism of active ingredient release of the tablets. The reference tablets Glucophage XR 750 were surveyed on form of tablet, average weight, hardness, abrasion, moisture content, identification, assay and dissolution to set up a database for the standards of tablets having the same amount of metformin hydrochloride. The test tablets having various rate and various inactive ingredient were prepared by wet granulation method, and then compared with the reference tablets. DDSolver (an addin program) was used for surveying and comparing the release kinetics and the mechanism of active ingredient release. The results showed that the test tablets containing 7.5% xanthan gum, 7.5% Acrypol 971p, and 15% magnesium alluminium silicate had the active ingredient release process equivalent to the reference tablets in pH 6.8 buffer medium when using apparatus 1 at 100 rpm (f2 =71.16, process similar to Test 1 USP 40). The test tablets also satisfied the USP 40 dissolution Test 1, 3, 8, 10, and 11, had the active ingredient release kinetics in accordance with the Korsmeyer-Peppas model (R2 =0.98; AIC=39.59). The release kinetics equation was the cumulative percentage of drug release , so the main mechanism of active ingredient release included diffusion and erosion. Metformin hydrochloride 750 mg extended release tablets that were prepared in this study had the dissolution equivalent to the reference tablet Glucophage XR 750 according to the USP 40 standard.