A NOVEL OPHTHALMIC DRUG DELIVERY SYSTEM: IN-SITU GEL

The ophthalmic in-situ gels now days proved an palpable sustained drug delivery in various eye diseases. The formulation of in-situ gels for eye which carries the advantages like easy for administration, reduces frequency of dose and improves patient compliance. The formation of in-situ gels depends on phase transition system or sol-gel transition system. The formulation approaches like temperature intonation, pH change and presence of ions from which the drug gets released in a sustained and controlled manner are utilised for in-situ gels. Various polymers that are used for the formulation of in-situ gels include chitosan, Pluronic F-127, poly-caprolactone, gellan gum, alginic acid, xyloglucan, pectin etc. INTRODUCTION: Ophthalmic drug delivery is one of the challenging endeavors facing the pharmaceutical scientist today. The structural and functional aspects of the eye render this organ highly impervious to foreign substances. A significant challenge to the formulator is to overcome the protective barriers of the eye without causing permanent tissue damage. The major problem encountered with topical administration is the rapid pre‐corneal loss caused by nasolacrymal drainage and high tear fluid turnover which leads to only 10% drug concentrations available at the site of actions . In the last decade, greater attention has been focused on development of controlled and sustained drug delivery systems. Many patents for their use in various biomedical applications including drug delivery have been reported . Eye seems an ideal, easily accessible target organ for topical treatment. However the eye is in fact well protected against absorption of xenobiotics, first by the eyelids and tear-flow and then by the cornea, which forms the physical-biological barrier. Poor bioavailability of drugs from ocular dosage forms is mainly due to the tear production, non-productive absorption, transient residence time, and impermeability of corneal epithelium . Most ocular treatments like eye drops and suspensions call for the topical administration of ophthalmic drugs to the tissues around the ocular cavity. These dosage forms are easy to instil but have the inherent drawback that the majority of the medication in them is immediately diluted. Extensive research has been carried in designing of polymeric drug delivery systems.