SOLUBILITY AND DISSOLUTION ENHANCEMENT OF A BCS CLASS II DRUG BY CO-GRINDING WITH SUPERDISINTEGRANTS

Majority of drugs administered by oral route exhibit low bioavailability because of their limited water solubility. Atorvastatin calcium (ATR)-a potent antihyperlipidemic drug- is a poorly soluble BCS class II drug. Present investigation was aimed at solubility and dissolution enhancement of ATR by co-grinding it with superdisintegrants. Atorvastatin calcium was milled with crospovidone(CP), croscarmellose sodium (CCS) and sodium starch glycolate (SSG) in different ratios using a ball mill. Prepared co-ground mixtures were evaluated by saturation solubility studies, Fourier Transform Infrared (FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), and Scanning Electron Microscopy (SEM). Infrared spectrum ruled out any chemical interactions between drug and superdisintegrant. DSC and XRD studies proved that the co-grinding has caused reduction in drug’s crystalline characteritics. Also, SEM study indicated micronisation and intimate mixing of drug particles with superdisintegrant. Solubility studies revealed significant solubility enhancement in all co-ground mixtures than that of pure drug and drug milled alone. Tablets were formulated from all co-ground mixtures and evaluated. All the tablet formulation containing co-ground mixture exhibited improved in-vitro dissolution. Co-ground mixture with superdisintegrant CCS showed highest solubility and dissolution enhancement in the ratio 1:3. The optimized tablet formulation (F6) displayed better dissolution profile than a marketed formulation. Thus, solubility and dissolution of ATR was successfully enhanced by co-grinding it with superdisintegrants. Co-grinding with superdisintegrant could be concluded as a simple, novel and effective tool for solubility and dissolution enhancement of BCS class II drugs.