Residence time.

Among the different routes of drug administration the oral route is most successful and popular. Dosage forms with a prolonged gastric residence and controlled drug delivery are called as Gastroretentive Drug Delivery System. Thus, these dosage forms significantly extend the period of time over which the drugs may be released in comparison to other Controlled Release Drug Delivery System. Different objectives that are to be achieved during development of gastro retentive drug delivery system are as it should increase bioavailability of drug, increase residence time of dosage form in stomach, achieve greater patient compliance by reducing frequency of dosing, better safety profile, achieve the improved economy of dosage form.This review covers major aspects of stomach anatomy and physiology, factors, rational, objectives, approaches, evaluation of gastroretentive drug delivery system.