Gastro retentive drug delivery systems are the systems which are retained in the stomach for a longer period of time and thereby improve the bioavailability of drugs. Different approaches for gastro retentive dosage forms include ß oating, raft, expanding/swelling, bioadhesive/ mucoadhesive and high/low density systems.Famotidine, an anti-ulcer drug, suffers from poor bioavailability (50% as famotidine is less soluble in alkaline pH. Famotidine used in combination with antacids promotes local delivery of these drugs to the receptor of the parietal cell wall. Local delivery also increases bioavailability at the stomach wall receptor site and increases the efÞ cacy of drugs to reduce acid secretion. This study aim to formulate ß oating tablets of famotidine using an effervescent approach for gastroretentive drug delivery system. Floating tablets were prepared using direct compression techniques using polymers like HPMC K4M and HPMCK100M for their gel-forming properties. The HPMC polymer alone is unable to control release rate. It releases drug >90% in four to six hours. In combination with Xanthan gum it release >90% in eight hours. The results indicate that gas generated gastroretentive ß oating tablets of famotidine containing HPMCK100M and Xanthan gum provide better options for controlled release action and improved bioavailability.
Key words: Famotidine, HPMC K4M, HPMC K100M, xanthan gum, swelling index.