Design and Evaluation of In-Situ Ophthalmic Gel Containing Carbopol and Methylcellulose as Viscosity Modifier

To increase the bioavailability of the drug in eye it is necessary to increase the residence time of the formulation with minimum solution drainage and untoward disposition of the instilled dose. The reliable method to overcome the above problem is in-situ ophthalmic gel. Combination of carbopol 940, a pH dependent polymer and methyl cellulose A4M, a thermo sensitive polymer were used for present research. The total six batches were prepared and subjected to the evaluation. Rheological studies, gel strength measurement, bioadhesion force measurement, drug content uniformity, in-vitro release study were carried out for all formulations. In-vitro study shows drug release up to 12 hrs. The in-vitro study data treated with various kinetic equations revealed that drug release follows first order diffusion controlled by Fickian diffusion mechanism. The optimized batch is subjected to eye safety evaluation, stability study and comparison with marketed preparation for in-vitro release. The present formulation shows the negligible difference in drug release as compare to the marketed preparation. Hence it is concluded that the present formulation will perform well in the eye upon instillation as in-situ gel.