Chapter 6 - Gastroretentive drug delivery approaches for oral bioavailability improvement

Abstract

The success of controlled oral drug deliveries is associated with some physiological adversities, like short gastric residence time (GRT) and unpredictable gastric emptying time. Prolonged GRT increases the duration of drug release, reduces drug waste, and improves drug solubility in gastric pH. This has triggered attention toward the development of gastroretentive drug delivery systems (GRDDSs) to deliver drugs with narrow absorption windows with improved bioavailability. The current chapter addresses briefly the current status of various leading GRDDSs developed until now, that is, floating drug releasing systems (FDDSs) imparting sufficient buoyancy in the gastrointestinal (GI) fluid, biomucoadhesive drug releasing systems imparting sufficient biomucoadhesion to the GI mucosal surfaces, high density or sinking drug releasing systems capable of retaining at the underside of the stomach, unfoldable, flexible, or swellable drug releasing systems limiting the gastric emptying of the drug dosage forms via the pyloric sphincter, superporous hydrogel-based systems, magnetic systems, etc. In addition, anatomy and physiological aspects of GRDDSs, important factors controlling the gastroretention of dosage forms, essential excipients for designing GRDDSs, evaluation of GRDDSs, advantages, and disadvantages are discussed.