FORMULATION DEVELOPMENT AND EVALUATION OF pH TRIGGERED IN SITU OPHTHALMIC GEL OF EPINASTINE HYDROCHLORIDE

The poor bioavailability of ophthalmic solutions caused by dilution and drainage from the eye can be overcome by using in situ forming ophthalmic drug delivery system prepared from polymer that exhibit reversible liquid–gel phase transition.  The objective of the study was to develop optimized formulation of  in situ ophthalmic gel of Epinastine hydrochloride, an antihistaminic drug, using a pH triggered polymer, Carbopol as a gelling polymer and HPMC E-50LV (hydroxyl propyl methyl cellulose) as release retardant. The 32 full factorial design was employed to optimize the formulation considering Carbopol and HPMC as independent variables. The formulations were assessed for appearance, gelling ability, sterility, pH, drug content, viscosity, release through cellophane membrane & corneal membrane of goat, ocular irritation study & stability study as per ICH guidelines. Formulations F3 and F7 were found to be the good formulations from the nine formulations developed by 32 factorial design. The study revealed that the in situ system of epinastine hydrochloride sustained the effect of drug to 12 hours. The formulations F3 and F7 extended the release of drug upto 12 hours as compare to marketed product (EPINA eye drops) which released 99.22% release within 6hrs.