SOLUBILITY ENHANCEMENT OF POORLY WATER SOLUBLE DRUG ATORVASTATIN CALCIUM BY SOLID DISPERSION TECHNIQUE USING NATURAL CARRIER

Atorvastatin calcium (ATC) is an oral anticholesteremic agent. ATC belongs to BCS class II drug having high permeability but low aqueous solubility. In order to get beneficial therapeutic effects, its water solubility needs to be increased. In the present study, attempt was made to improve solubility and dissolution rate of ATC by formulating it into solid dispersion using maltose monohydrate as a highly water soluble carrier. Three methods were used for preparing solid dispersion, namely, physical mixture, kneading and solvent evaporation method in 1:1, 1:3 and 1:5 drug-carrier ratios. The FTIR study of ATC, its combination with the carrier, and of the sold dispersion indicated no interaction between drug, carrier and other excipients used. The prepared solid dispersion showed improved solubility and dissolution rate as compared to pure drug. The improvement in solubility may be attributed to the improved wettability of ATC due to uniform dispersion into the carrier. The optimized batch was K2, which was prepared by kneading method in 1:3 ratios. The optimized batch released 99.59 % drug within 60 min and had solubility almost five folds higher than pure ATC. From the solubility values it was clear that kneading method was more suitable than the other two methods used for preparing solid dispersion. The XRD studies revealed that the crystalline nature of ATC was reduced when formulated into solid dispersion. The optimized batc