An Overview of In Situ gelling system

Abstract

Conventional liquid formulation for drug delivery shows low bioavailability because of rapid gastric emptying time from stomach/ duodenum or rapid precorneal drug loss from eye etc. Hence to improve the bioavailability of drug, In situ forming polymeric drug delivery system could be a better option. Intially they are in sol form before administered in the body, but once administered; undergo gelation in situ to form a gel. The controlled release of drug molecules via In situ forming system has a number of advantages, such as ease of administration, less complicated fabrication, less stressful manufacturing condition for sensitive drug molecules. The constant drug release may be achieved via various polymers (gellan gum, alginates, pectin, xyloglucans, PEO-PPO-PEO, poly (acrylic acid), poly (N-isopropyl acrylamide), chitosan) obeys Fick’s law of diffusion which can be better explained by “egg box model”. The possible mechanism from which above polymers forms In situ gel are: solvent exchange, UV- irradiation, pH change, osmotic pressure change, ionic cross linkage and temperature changes. These polymeric formulations possibly are administered by oral, rectal, ocular, vaginal, injectable and intraperitoneal routes. This article deals with the detail review of polymeric systems, their evaluation, biomedical applications, mechanism of polymer gelation, factor affecting polymers gelation, commercial formulation and their limitations.