Abstract

SOLUBILITY AND BIOAVAILABILITY ENHANCEMENT OF POORLY WATER-SOLUBLE DRUG GLIMEPRIDE

Vishal Singh Rao*, Gajendra Singh Rathore, Sibi K

Abstract

The present study owed to enhance the dissolution and potential bioavailability of poorly water-soluble glimepiride (GP) through the formulation of solid dispersions using suitable hydrophilic carriers. Solid dispersions and physical mixtures of glimepiride were prepared employing poloxamer 188 and crospovidone as carriers. Glimepiride–poloxamer 188 solid dispersions were developed by melting and solvent evaporation methods, whereas glimepiride–crospovidone systems were prepared by adsorption onto an insoluble carrier. The prepared formulations were evaluated for percentage yield, drug content, solubility in pH 6.8 phosphate buffer, X-ray diffraction (XRD), scanning electron microscopy (SEM), in vitro dissolution, and dissolution efficiency. Among the developed formulations, the glimepiride–poloxamer 188 solid dispersion prepared by the melting method in a 1: 4 drug-to-carrier ratio (GP4)] demonstrated the highest dissolution rate and dissolution efficiency. Based on these findings, GP4 was selected for tablet formulation. Solid dispersion tablets were prepared by direct compression using varying concentrations (2–5%) of the super-disintegrant Ac-Di-Sol. The formulated tablets were further evaluated for physical appearance, thickness, hardness, friability, disintegration time, drug content, and in vitro drug release. Tablets containing 5% Ac-Di-Sol (T5) exhibited the shortest disintegration time and the highest dissolution efficiency among all formulations. The study suggested that solid dispersion technology is an effective e and economical approach for improving the dissolution characteristics of poorly soluble drugs. Enhancement in dissolution was mainly attributed to improved wettability, reduction in particle size, decreased crystallinity, reduced agglomeration, and conversion of the drug into an amorphous state.

Keywords: Glimepiride, Solid dispersion, Poloxamer 188, Crospovidone, Dissolution enhancement, Bioavailability.