In-Situ Gel Formation for Ocular Drug Delivery System an Overview

Ophthalmic In-situ gels are viscous polymer‐based liquids that exhibit sol‐to‐gel phase transition on the ocular surface due to change in a specific physicochemical parameter like ionic strength, pH or temperature Gel dosage forms are successfully used as drug delivery systems considering their ability to prolong the drug release. To prolong the precorneal resident time and improve ocular bioavailability of the drug various polymers system were studied as in situ gelling vehicle for ophthalmic drug delivery system. The In situ formulation exhibited well, viscosity, drug content and sustained drug release. Conventional liquid ophthalmic formulations demonstrate low bioavailability because of a constant lacrimal drainage in the eye. The normal drainage of an instilled drug dose commences immediately upon instillation and is essentially completed within 5 min. typically ophthalmic bioavailability of only 1–10% is achieved due to the short precorneal residence time of ophthalmic solutions. Each system has its own advantages and drawbacks. The choice of a particular hydrogeldepends on its intrinsic properties and envisaged therapeutic use. This review includes various temperature, pH, and ion induced in situ-forming polymeric systems used to achieve prolonged contact time of drugs with the cornea and increase their bioavailability. Ophthalmic drug delivery is one of the most interesting and challenging endeavors facing the pharmaceutical scientist. The conventional ocular drug delivery systems like solutions, suspensions, and ointments show drawbacks such as increased precorneal elimination, high variability in efficiency, and blurred vision respectively.