Formulation and Evaluation of Gastroretentive Floating Matrix Tablets of Atorvastatin Calcium

The present work focuses on the development of hydrodynamically balanced delivery system of Atorvastatin as a single-unit floating Tablet which, after oral administration should have the ability to prolong gastric residence time with the desired in vitro release profile for the localized action in the stomach. Fourier transform Infrared spectroscopy and DSC study confirmed the absence of any drug/polymers/excipients interactions. Floating effervescent tablets were formulated by various materials like. hydroxypropyl methylcellulose (HPMC) K4M, K15M, psyllium husk, swelling agent as crospovidone and micro crystalline cellulose and gas generating agent like sodium bicarbonate and citric acid and evaluated for floating properties, swelling characteristics and drug release studies. Floating non effervescent tablets were prepared by polypropylene foam powder and different matrix forming polymers like HPMC K4M, Carbopol 934P xanthan gum and sodium alginate. The Tablets were prepared by wet granulation method and the polymer in varying ratios. The prepared floating tablets were evaluated for hardness, weight variation, thickness, friability, drug content uniformity, buoyancy lag time, total floating time, water uptake (swelling index) and in-vitro dissolution studies Incorporation of gas- generating agent together with polymer improved drug release, besides optimal floating. The formulation was optimized on the basis of in vitro buoyancy and in vitro release in 0.1N HCl. By fitting the data into zero-order, first-order, and Higuchi models, we concluded that the mechanism of release of Atorvastatin from the floating tablet was anomalous diffusion transport and follows zero order kinetics, as the correlation coefficient (R value) was higher for zero-order release. Stability studies revealed that formulations were stable when stored at different temperatures and the values were within permissible limits.