A REVIEW ON OCULAR IN SITU GEL

Ophthalmic drug delivery presents major challenges for pharmaceutical and medicinal sciences. New ocular drug delivery forms are various; they included in situ gelling systems, liposome's, nanoparticles, noisome, nanoemulsions and microemulsions. They are suitable for hydrophilic or lipophilic drugs, have the capacity of targeting a specific site and can be administrated in different routes. With the appropriate excipients, in situ gelling systems are able to increase the precorneal residence time and decrease the loss of drug due to the tear. In situ gelling system is a formulation that is in solution form before entering in to the body, but it will change to gel form under various physiological conditions. The sol to gel transition depends on various factors like temperature, change in pH, solvent exchange, UV radiation, and presence of specific molecules or ions. Pectin, gellan gum, chitosan, alginic aicd, guar gum, carbopal, xyloglucan, xantham gum, HPMC, poloxamer etc are some of natural polymers used for in situ gelling system. This review on ocular in situ gel to enhance the bioavailablity of cyclosporine, prolonged retention time of drug, using various polymers for eyes remain moist for longer time, evaluation.