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Enhancement of Solubility of Repaglinide by Solid Dispersion Technique

R. Kavitha and A. Abdul Hasan Sathali

The present study involved preparation of solid dispersions of repaglinide to improve the aqueous solubility and dissolution rate in order to enhance bioavailability. Repaglinide is a BCS Class II drug, having low aqueous solubility and therefore, low bioavailability. In the present study, solid dispersions of repaglinide with different carriers [poly ethylene glycol 6000 (PEG 6000), poly vinyl pyrrolidone k30 (PVP K30), poloxamer 188 and crospovidone in different ratios (1 : 1, 1 : 2, 1 : 4, 1 : 6)] were prepared by melting and solvent evaporation methods. In vitro release studies revealed that the solid dispersions prepared by solvent evaporation method showed faster drug release when compared to the melting method. So, the dissolution profile of solid dispersion containing PVP K30 (1 : 4) was selected as the best formulation because of its faster drug release among all formulations. X-ray diffraction spectral studies showed a significant decrease in crystalline nature of drug in solid dispersions which resulted in increased dissolution rate of repaglinide. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR) studies of solid dispersion revealed that no interactions exist between drug and polymer. Phase solubility studies of the best formulation indicated that the solubility was improved compared to the pure drug. Similarly tablets prepared from solid dispersed drug had better dissolution than tablets prepared from normal drug powder. In conclusion, solid dispersions of repaglinide in PVP K30 have shown to be a promising approach to improve the bioavailability of repaglinide.