AN OVERVIEW OF GASTRO RETENTIVE DOSAGE FORMS (GRDFS)
Abstract
Gastro retentive drug delivery is an approach to prolong gastric residence time, thereby targeting site-specific drug release in the upper gastrointestinal tract (GIT) for local or systemic effects. Prolonged gastric retention improves bioavailability, reduces drug waste and improves solubility for drugs that are less soluble in a high pH environment. Gastro retention helps to provide better availability of new products with new therapeutic possibilities and substantial benefits for patients. The goal of any drug delivery system is to provide a therapeutic amount of drug to proper site in the body to achieve promptly and then maintain a desired drug concentration. Various dosage alternatives found by recent development can be administered via different routes of administration. Various routes that are used include oral, topical, nasal, rectal, vaginal and ocular, etc. The oral delivery of drugs is considered to be the most appealing route of administration. This belief has led to the identification of many very successful drugs, but also saw the downfall of some promising therapeutics that failed to meet criteria required for sufficient oral bioavailability. The use of solid dispersion technologies for improving the dissolution characteristics of poorly water-soluble drugs and in turn their oral bioavailability has become a major point of attraction. Formulation of drugs as solid dispersion offers a variety of processing and excipient options that allow for flexibility when formulating oral delivery systems for poorly water-soluble drugs. Much of the research that has been reported on solid dispersion technologies involves drugs of class III of BCS classification. Hence, the hypothesis has been that the rate of absorption in vivo will be concurrently accelerated with an increase in the rate of drug dissolution.
Keywords: gastric residence time, bioavailability, oral delivery of drugs, solid dispersion technologies, BCS classification.