RESUMO
The conventional oral drug delivery systems face a lot of difficulties in the gastrointestinal tract, such as inappropriate drug release and reduction in the efficacy of the doses, which makes this system less susceptible to the delivery of drug formulation. For the enhancement of therapeutic efficacy and bioavailability of the drug, many efforts have been made. The drug candidates which are not stable at alkaline pH and soluble in acidic medium were selected to increase their therapeutic effectiveness through gastro retentive drug delivery systems (GRDDS). This article discusses various factors which alter the gastro retention time (GRT) of the gastro retentive drug delivery system in the stomach and intestine (duodenum). It emphasizes on the novel approaches made for the delivery and release of drugs with the use of magnetic systems, floating (low-density) systems, super porous hydrogels, raft systems, mucoadhesive systems, high-density systems and expandable systems. Along with the applications, the key aspects of in vivo, in vitro & clinical studies in different approaches to GRDDS have been addressed. In addition, future perspectives have been summarized to reduce gastric transit time in fasting and fed conditions.