Comparative In-vitro Evaluation of Metformin HCl Extended Release Tablets Marketed in Syria

Abstract

Metformin hydrochloride extended release tablets are available in many brands in the Syrian market, which make it difficult to select the safe, effective and economic one. The aim of this study was to evaluate the quality control standards of generic different brands of metformin extended release tablets, and compare them with the innovator Glucophage XR ® . Two brands AandB (two batches from each brand) were selected. The physiochemical equivalence of all tablets were assessed through the evaluation of weight variation test, assay, swelling behavior study and dissolution test which was carried out for 12 hours using USP apparatus Ι in phosphate buffer pH= 6.8 as a dissolution media. The release mechanism were explored and explained with zero order, first order, Higuchi and Korsmeyer-Peppas equations. In order to compare dissolution profiles, dissolution data was taken and compared through model independent- methods: difference factor f1, similarity factor f2 and dissolution efficiency DE. The tablets had been passed weight variation test and the percent of assay for all brands were within the acceptable ranges. Fitting dissolution data to Korsmeyer-Peppas equation indicated that diffusion along with polymer relaxation could be the mechanism of drug release from brand B and the reference, whereas Fickian diffusion was the predominant mechanism of metformin release from brand A. The study showed that, brand B had similar dissolution profiles with the reference (F2>50), whereas brand A was different in its release behavior (F2>15).