The objective of this research work was to improve the aqueous solubility and dissolution rate of repaglinide, a poorly water soluble anti-diabetic drug by solid dispersion technique. Hydroxyl propyl methyl cellulose and povidone K 30 were used as water soluble polymers for preparing solid dispersion of repaglinide. Solid dispersions were prepared by the solvent method. Methanol was used as solvent. Invitro drug release was studied. A significant increase, almost 100% in the release of repaglinide within one hour was observed in case of the solid dispersion formulations. Solubility study was also found very effective. After incorporating water soluble polymers the solubility of repaglinide was increased to a significant amount. Solubility after sonication in sonicator was more than the solubility after shaking in thermal shaker for six hours. Infrared spectroscopy was used to characterize drug-polymer interactions in solid dispersions. There were no significant interactions between the drug and the carriers. Thermal analysis by differential scanning calorimeter was studied to detect the physicochemical transition by measuring the amount of heat absorbed or released as the sample is heated across its suspected transition range. The results showed that the incorporation of polymers transforms crystalline repaglinide into amorphous state, thus increasing its solubility and dissolution rate.
