Comparing the dissolution profiles of seven metformin formulations in simulated intestinal fluid

Abstract

Dissolution testing is used to evaluate the performance of pharmaceutical products. This study compared the dissolution profiles of seven immediate-release metformin 500-mg formulations, including two products with the trade name Glucophage, in simulated intestinal fluid (SIF) at pH 6.8 buffer without enzymes. Other characteristics investigated were absolute weight and drug content. These formulations were marketed in Trinidad and Tobago and are categorized as Class 3 drugs by the Biopharmaceutics Classification System (BCS). The paddle apparatus was used at 75 rpm in 900 mL of SIF at 37 ± 0.5 °C. Samples of 1.25 mL were removed at 10, 15, 20, 30, 45, and 60 min without replacement, of which 100 μL was diluted with fresh medium and then analyzed spectrophotometrically at 233 nm. Data were analyzed statistically using one-way analysis of variance and DDSolver Add-In to Excel. The weights were significantly different (p " 0.05), and each of the formulations demonstrated drug content between 99% and 103%. Only one of the formulations showed <85% drug release in 15 min and a calculated f2 value less than 50, which deviates from the acceptance criteria recommended by the World Health Organization (WHO).