Assessment of Physicochemical Properties and Comparison of Dissolution Profiles of Metformin Hydrochloride Tablets in Saudi Arabia

Although prevalence of substandard or counterfeit drugs is a world-wide problem, poor and developing countries are affected the most. To be a quality product, drug formulation must comply with certain standards. Consequently, in this study, metformin hydrochloride (MH) tablets (500 mg) available in the Saudi Arabian market were assessed through various pharmacopeial quality control tests. Parameters including weight variation, hardness, friability, drug content, and disintegration time were evaluated. Results were within acceptable limits for all selected products (nine generic and an innovator). Fourier-transform infrared spectroscopy (FT-IR) spectra of MH for all tested products were completely superimposed with that of the pure drug, confirming the use of correct active ingredient in all tablet formulations. The products were also evaluated by comparing the dissolution profile of the generic products with the innovator brand in pH 6.8 phosphate buffer. The range of percent drug release in 30 min was 82.71–98.43%, in comparison to 91.86% for reference product, which complies with the USP-NF specification of at least 80% drug release in 30 min. The difference factor (f1), similarity factor (f2, except product H), and dissolution efficiency revealed that the dissolution profiles of the tested products were comparable to that of the reference product. These results show that the tested generic products were biopharmaceutically similar (except product H) to the innovator formulation. Therefore, the consumer can select any one of these equivalent products as a substitute for innovator product in case of cost concern or unavailability.