Solubility and Dissolution Rate Enhancement of Simvastatin by Adsorption on Magnesium Aluminum Silicate

Simvastatin (SIM), is an inactive lactone, anti-hyperlipidemic drug. The drug belongs to the class II group according to the biopharmaceutical classification system (BCS) with low bioavailability due to its low solubility. Adsorption technique is an effective technique for improving the solubility and dissolution rate of poorly soluble drugs by using the mesoporous silica. The present study aims to enhance the solubility and dissolution rate of SIM using such technique. Soluplus® and poloxamer 407 were used as surfactants besides magnesium aluminum silicate (MAS) as adsorbent. All the MAS loading SIM formulations were prepared by the solvent evaporation method in different drug: adsorbent: surfactant weight ratios, then evaluated for their percentage yield, drug content, water solubility, dissolution, crystal lattice using X-ray powder diffraction (XRD) and Differential Scanning Calorimetry (DSC) studies and Fourier Transform Infrared Spectroscopy (FTIR) for determination the drug- excipient interaction. All the prepared formula showed improvement of drug solubility. The best result was obtained with formula F8(SIM: MAS: SOLU 1:6:3) that showed, 91.3% yield, 85.5±0.19 % drug content,178.3 -fold increase in solubility compared to solubility of pure drug and 1.6-fold as compared to F6(without soluplus®) and 85.5 % of drug released within 30 minutes with reduced crystallinity of the drug and compatibility between the drug and the additives. Therefore, the adsorption technique can be considered as an efficient method for enhancing the solubility and dissolution rate of SIM.