Formulation and Evaluation of Solid Dispersions of an Anti-diabetic Drug

The present work investigates the dissolution and bioavailability characteristics of an anti-diabetic drug, Glimepiride. Glimepiride, is an oral hypoglycemic drug and has problems in bioavailability and bioequivalence due to its poor water solubility. In the present study, dissolution studies were carried out by using USP XXIV apparatus, for the drug glimepiride, and its binary systems (both physical mixture as well as solid dispersions of glimepiride). Infrared (IR) Spectroscopy, Differential Scanning Calorimetry (DSC), and X-ray Diffractometry (XRD) were performed to identify any physicochemical interaction between the drug and the carrier and its effect on dissolution behavior. Tablets containing solid dispersion products were formulated and compared with the commercial product. The commercial product and the tablet formulation under investigation were than characterized for their various physicochemical properties such as weight variation, % friability, disintegration and in vitro dissolution profiles. IR Spectroscopy, XRD, and DSC showed no change in the crystal structure of glimepiride thus indicating the absence of any interaction between the drug and the polymer. A significant improvement in the dissolution of glimepiride in solid dispersion products has been observed (>85% in 5 minutes). Also tablets containing solid dispersion exhibited better dissolution profile than commercial tablets. Thus, the solid dispersion technique can be successfully used for the improvement of dissolution of glimepiride.