in situ gel

The eye is one of the most delicate organs in our body. The eye is a complex organ characterized by its low permeability, short precorneal residence time, and small area for absorption, which pose significant barriers to drug delivery. Typically, less than 10% of a drug administered penetrates the eye. Traditional ocular delivery systems are also constrained, with significant drug loss due to tears and blinking, leading to blurred vision and untimed release events without sustained action, resulting in suboptimal outcomes in ocular therapy. To overcome such challenges, in situ ophthalmic gels have been developed. These gels' ability to transition from a liquid to a gel state allows for sustained drug release at the target site. In situ gel systems are in solution form before administration and then convert to a gel under physiological conditions (pH, temperature, or ionic concentration). This review discusses the anatomy and physiology of the eye, the challenges of ocular drug delivery, types of in situ gelling systems, mechanisms of gel formation, types of smart polymers, and methods for evaluating polymeric in situ gels.   

The aim of the present work was to formulate and evaluate in situ gelling system of levofloxacin hemihydrate. Levofloxacin hemihydrate is an antibacterial agent which exhibits rapid pre-corneal elimination and poor ocular bioavailability when administered in the form of conventional ophthalmic solutions like eye drop. To overcome this, an attempt has been made to formulate pH induced in situ gelling system of levofloxacin to provide sustained release of drug. Polymeric carriers that undergo sol-to-gel transition upon change in pH. The levofloxacin hemihydrate in situ gelling system formulated by using polyox in combination with hydroxyl propyl methyl cellulose (HPMC K4M) which acted as viscosity enhancing agent. The developed formulation was stable, non-irritant and provided sustained release over 8-hour period and can be a viable alternative to conventional eye drops. The formulations were found to be non-irritating.