Development of extended-release metformin core tablet and synergistic coating of sitagliptin for the treatment of type-II diabetes mellitus - A comparative drug release evaluation with reference product.

Diabetes is getting a common disease and is spreading rapidly, affecting 6.6 percent world's population. Metformin HCl is an effective pharmacological treatment for type 2 diabetic patients because of its lowering blood glucose level ability, better weight-neutral effects and reduced risk of hypoglycemia. Nevertheless, gastrointestinal (GI) sensitivities are a concern in many patients using its immediate-release formulations. This study aimed to develop extended-release (ER) formulations to control the release into the body and minimize the dosage-related side effects of metformin and to develop an effective method of coating Sitagliptin immediate-release (IR) formulation over the core tablet. This study evaluated different formulations of Metformin HCl ER tablet using hydrophilic polymers. Different concentrations of Sitagliptin were used to develop immediate release coating. The dissolution profile of the designed formulation was compared with the reference 50/500mg tablet. In vitro dissolution of Metformin HCl (MT5), containing Methocel K4M and Methocel K100 polymer, showed 37.62% release at 1hr, 53.46% at 2hr, 84.75% at 6hr and 94.81% at 10hr. The Sitagliptin (ST8) with 10% excess released 103.64% in 30min. Similarity factor values suggested that developed Metformin ER and Sitagliptin IR formulation were like the reference product.