pH-induced in situ gelling system of an anti-infective drug for sustained ocular delivery

Recently, in situ gel formation has been extensively studied to enhance ocular bioavailability and the duration of drug activity. Poor ocular bioavailability of drugs (<1%) from conventional eye drops is mainly due to the precorneal loss factors that include rapid tear turnover, nonproductive absorption, transient residence time in the cul-de-sac, and the relative impermeability of the drugs to corneal epithelial membrane. These problems may overcome by the use of in situ gel-forming systems that are instilled as drops into the eye and undergoes sol-gel transition in the cul-de-sac. In this study, in situ gelling system of Gatifloxacin were prepared using polymers carbopol 940 (0.1% to 0.5% w/v) and HPMC E4M (0.2% to 0.6% w/v). The developed formulation was characterized for various in vitro parameters such as clarity, temperature, pH, tonicity, sterility, rheological behavior, drug release profile, transcorneal permeation profile, and ocular irritation. Developed formulation was clear isotonic solution, converted into gel at temperatures above 35 °C and pH 6.9–7.0. The results demonstrated that the carbopol/ HPMC mixture can be used as an in situ gelling vehicle to enhance the ocular bioavailability of Gatifloxacin. The developed system is a viable alternative to conventional eye drops for the treatment of Bacterial conjunctivitis and various other ocular infections.