Frmulation and evaluation of in-situ gel for glaucoma by β-blocker

Abstract

The low bioavailability and ocular residence time exhibited by the topical conventional liquid ophthalmic formulations because of spillage by overflow, dilution of drug by tear turn over, nasolacrimal drainage and systemic absorption may be overcome by the use of in-situ forming systems that are instilled as liquid drops into the cul-de-sac of the eye, where they transform into a gel or semisolid phase. Formulation and evaluation of an ophthalmic delivery system of an antiglaucomatic drug, betaxolol HCl used for the treatment of ocular hypertension, open angle and angle closure glaucoma was formulated based on the concept of ion-activation in-situ gelation from where the drug is released for a period of 7 h. Specific polymers like gelrite and sodium alginate were used as gelling agents in ion-activated system. Sodium alginate in combination with HPMC E50LV was proved to retain the gel formation for extended period of time, due to the enhancement of viscosity factor but it developed haziness after the 1 month of accelerated stability studies so it was discarded. The drug betaxolol HCl in an in-situ gel drug delivery system was found to be compatible to release the drug into the cul-de-sac gradually, thereby increasing the therapeutic efficacy to maximum within less time and preventing any drug loss. It also contributes to a great extent to patient compliance as the dosage is regulated as one drop of the solution to be instilled into the eye once in a day. Stability was established as per ICH guidelines. There was no incompatibility of the formulation contents as per FTIR studies. In vivo irritation studies conducted on Albino rabbits indicated no irritation or inflammation at the site of action.