Preparation, characterization, and dissolution behavior of a solid dispersion of Simvastatin with polyethylene glycol 4000 and polyvinylpyrrolidone K30

The aim of the present study was to improve the solubility and dissolution rate of a poorly water-soluble drug, Simvastatin, by a solid dispersion technique. Solid dispersions were prepared with polyethylene glycol 4000 (PEG 4000) by fusion-cooling and solvent evaporation techniques whereas with polyvinylpyrrolidone K30 (PVP K30) by solvent evaporation technique in different drug-to-carrier ratios. These new formulations were characterized in the liquid state by phase solubility studies and in the solid state by differential scanning calorimetry, x-ray powder diffraction, and FTIR spectroscopy. The aqueous solubility of Simvastatin was favored by the presence of both polymers. Solid state characterization indicated Simvastatin was present as amorphous material and entrapped in polymer matrix. Solid dispersion prepared with PVP showed highest improvement in wettability and dissolution rate of Simvastatin. Tablets containing solid dispersion prepared with PEG and PVP showed significant improvement in the release profile of Simvastatin as compared to tablet containing Simvastatin without PEG or PVP.