ABSTRACT
The development of formulations with enhanced gastric residence time has gained considerable attention of researchers. Prolongation of gastric residence plays an important role in enhancement of oral bioavailability of drugs having absorption window in the stomach. There is a possibility of reduction in toxicity of drugs which cause intestinal irritation by formulating them as gastro-retentive dosage forms. The effectiveness of locally acting drugs such as antacids and antibiotics can be improved by prolonging their gastric residence. Gastro-retentive formulations may lead to enhancement in oral bioavailability and stability, reduction in toxicity and inhibition of P-glycoprotein efflux. Various approaches such as floating, high density, bioadhesive and expandable systems have been reported for prolongation of gastric residence. The characterizations of these systems including the in-vitro and in-vivo studies have been explained in detail. Thus, the current chapter endeavors to discuss the stellar merits and limitations of each approach, their evaluation and characterization aspects including gastroretention and bioavailability studies. Each of such systems has also been duly illustrated citing laboratory instances, and/or apt literature reports.
