Formulation and Evaluation of Sustained Ophthalmic Gel Forming System of Levofloxacin

Conventional ophthalmic solutions often eliminate rapidly after administration and can’t provide and maintain an adequate concentration of drug in the precorneal area. This can be overcome by the use of in situ gel forming systems that are instilled as drops into the eye and undergo a sol-gel transition in the culde-sac. The present work describes the formulation and evaluation of an ophthalmic delivery system of an antibacterial agent, levofloxacin, based on the concept of pH sensitive and temperature sensitive in situ gelation. The pH sensitive polymer Carbopol 940 and temperature sensitive Poloxamer 407 were used as gelling agent with HPMC E50LV which acted as viscosity enhancing agent. These combine solution would convert to form gels under physiological condition. The rheological properties and in vitro drug release test of various formulations were evaluated. In this study, 2 full factorial designs was used to investigate the joint influence of three formulation variables, amount of Poloxamer 407, Carbopol 940 and amount of HPMC E50LV at two level. The results of multiple linear regression analysis revealed that for obtaining desired viscosity and in vitro release pattern, eye drops should be prepared using an optimum concentration of all three polymers. The formulations showed a significant gelling in physiological condition. In vitro release study demonstrated diffusion controlled release of levofloxacin from formulations over a period of 6-8 h. The results also demonstrated that Carbopol/Poloxamer mixture can be used along with HPMC E50LV as in situ gelling vehicle to enhance patient compliance. The developed formulation was therapeutically efficacious, stable, non-irritant and provided sustained release of drug over a period of 6-8 h. The developed system is thus a viable alternative to conventional eye drops.