Atorvastatin solid dispersion for bioavailability enhancement

Atorvastatin calcium is a lipid-lowering agent. It has approximately 15% of bioavailability, remaining amount of drug showed adverse effect which is undesirable for patients. The objective of the study was to enhance the solubility and a dissolution profile of the atorvastatin (AT) calcium. Solid dispersion (SD) is a technique which enhances the solubility and a dissolution profile of poorly soluble drug. Various methods are being used for SDs such as microwave irradiation fusion, kneading, solvent evaporation, fusion, and dropping method. The authors have used here conventional fusion method using PEG 4000 as a hydrophilic carrier. The solubility of pure drug, physical mixture using PEG 4000 (1:3), and SD in phosphate buffer solutions (pH 6.8) was found to be 55.33 ± 0.66, 81.89 ± 2.35, and 93.66 ± 1.35, respectively. Fourier transform infrared and differential scanning calorimetry study showed the significant peak shift of drug in SD. It indicated that the nature of drug had been changed from crystalline form to amorphous form due to conversion into SD formulation. The dissolution rate was significantly increased when the drug polyethylene glycol 4000 ratio was 1:3. The mean cumulative percentage drugs release from pure drug, physical mixture, marketed tablet, and SD at 1 h was 28.92 ± 1.66%, 55.26 ± 0.95%, 72.16 ± 1.33%, and 91.66 ± 1.65%, respectively. It was concluded that the solubility and dissolution profile of SD of AT calcium showed the enhancement of solubility and dissolution when compared with marketed preparations.