Solubility and Dissolution enhancement of simvastatin usingsynergistic effect of hydrophilic carriers

Simvastatin, a hypolipidemic drug is widely used in the treatment of hyperlipidemia. One of the major problems with this drug is its low solubility in biological fluids, which results into poor bioavailability after oral administration. Therefore solid dispersion of simvastatin was prepared using hydrophilic carriers Polyethylene glycol 6000 (PEG 6000), Sorbitol, Gelucire 44/14 to increase its aqueous solubility. The solid dispersions were prepared by fusion and solvent evaporation method. In-vitro release profiles of all solid dispersions were comparatively evaluated and also compared with pure Simvastatin. The prepared solid dispersions were characterised for drug content, infrared spectral studies, differencial scanning calorimetric studies, scanning electron microscopy and aqueous solubility studies. From the results it was clear that solid dispersion formulations showed improved dissolution rate than pure drug and physical mixtures. Also solid dispersions prepared using multiple carriers showed enhanced dissolution as compared to the ones prepared using single carriers. Finally solid dispersion of Simvastatin: PEG 6000: Sorbitol: Gelucire 44/14 prepared in the ratio of 1:1:1:1 (SIM 17) showed excellent physico-chemical characteristics and better release profile than the other solid dispersions.