Several approaches have been proposed to retain the dosage forms in the stomach. These methods include bioadhesive system, swelling system and expanding system and floating system. In fact the buoyant dosage unit enhances gastric residence time (GRT) without affecting the intrinsic rate of emptying. Unfortunately floating devices administered in a single unit form ( Hydrodynamically balanced system) HBS are unreliable in prolonging the GRT owing to their ‘all- or- nothing’ emptying process and, thus they may causes high variability in bioavailibity and local irritation due to large amount of drug delivered at a particular site of the gastrointestinal tract.