OPTHALMIC IN SITU GEL: A REVIEW
*Priyanka D. Dabir, Dr. S. R. Shahi and Swati V. Deore
The poor bioavailability of conventional ophthalmic formulations is due to rapid precorneal drug loss ( through dilution and drainage from the eye). There are some static (different layers of the eye i. e. cornea, sclera, retina) and dynamic barriers (blood aqueous and blood retinal barrier) which also affect the bioavailability of drug. The problem can be overcome by using in situ forming ophthalmic drug delivery system prepared from polymer that exhibit reversible liquid–gel phase transition. In situ gels are the liquid preparations which upon instillation undergoes phase transition in cul-de-sac of the eye to form a viscous gel and this occurs due to the environmental changes in the eye (i.e. due to change in temperature, change in pH and ion induced change). This novel drug delivery system promotes the importantly ease and convenience of administration, deliverance of accurate dose as well as to prolong residence time of drug in contact with mucosa. The primary requirement of a successful control release product focuses on increasing patient compliance, good stability and biocompatibility characteristics which make the in situ gel dosage forms very reliable. This review is to specify the basic anatomy and physiology of human eye, various approaches used for formulation of in-situ gels and polymers used in the formulation of in situ gels.
Keywords: In situ gel, in situ gelling polymers, pH sensitive, temperature sensitive, ion sensitive.
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