MISHRA JHANSEE, DASHALOK KUMAR
Several controlled oral drug delivery systems with prolonged gastric residence time have been reported recently. Gastro retentive drug delivery system is an approach toprolong gastric residence time, thereby targeting site-specific drug release in upper gastro intestinal tract improving the oral sustained delivery of drug that have an absorption window in a particular region of the gastrointestinal tract. These systems help in continuously releasing the drug before it reaches the absorption window, thus ensuring optimal bioavailability. Various approaches for gastric retention are Floating system, Swelling and expanding system, Bioadhesive systems, Modified-shape systems, High density systems etc.