A COMPREHENSIVE REVIEW ON GASTRORETENTIVE DRUG DELIVERY SYSTEMS

The purpose of writing this review was to investigate, compile, recent, current and past literatures. In recent years several advancements has been made in research and development of oral drug delivery system. Various drugs, which are unstable in alkaline pH, soluble in acidic pH, having narrow absorption window, site specific to stomach can be developed by using this technique. Gastroretentive drug delivery systems (GRDDS) can improve the controlled delivery of drugs that have an absorption window by continuously releasing the drug for a prolonged period of time before it reaches absorption site. These include floating system, swelling system, expanding system, low density systems, high density system, bioadhesive and mucoadhesive systems etc. In fact the buoyant dosage unit enhances gastric residence time (GRT) without affecting the intrinsic rate of emptying. GRDDS is an approach to prolong gastric residence time, thereby targeting site-specific drug release in upper gastro intestinal tract improving the oral sustained delivery of drug. For minimizing the limitations and achieving better gastric retention various combinational approaches like floating and swelling, floating and bioadhesion, etc., multi-particulate systems, super porous hydrogel etc., have been discussed. The present review addresses briefly about suitable drug candidates, formulation considerations, physiological difficulties and classification, factors effecting gastric retention, merits, demerits and limitations of gastroretentive drug delivery systems. Keywords: Gastroretentive drug delivery systems, controlled release systems, gastric residence time, gastric emptying time and absorption window.