TEMPERATURE TRIGGERED IN-SITU GELLING SYSTEM FOR OCULAR ANTIVIRAL DRUGAbstract
The bioavailability of conventional ophthalmic solutions is very poor due to efficient protective mechanisms of the eye, blinking, reflex lachrymation, and drainage, which remove rapidly various foreign substances, including drug, from the surface of the eye. Frequent installation of a drug solution is necessary to maintain a therapeutic drug level in the tear or at the site of action. The recent trends in ocular drug delivery are in-situ gelling systems, occuserts, dry drops, and gel foams. Acyclovir is a potent antiviral drug of low toxicity. Acyclovir has low oral bioavailability and a short half-life. In the present research work, Acyclovir in-situ gelling systems were prepared by using temperature triggered polymer. The formulations were evaluated for several parameters like drug-polymer interaction, clarity, pH measurement, drug content (%), gelling capacity, gelation temperature, viscosity, sterility, isotonicity, in-vitro drug release studies, eye irritation, and short term stability studies. At low temperature, the prepared formulations were in a liquid state, however as the Pluronic F-127 present in the prepared formulation comes in contact with the tear fluid, the solution gets transformed into a gel with high viscosity at body temperature 37 ºC. Increasing the viscosity of a drug formulation in the precorneal region will lead to increased bioavailability due to slower drainage from the cornea. In the developed formulation, F6 was selected, which exhibits 10 h release with non-irritating, sterile, and stable properties, thus increasing the residence time of the drug with better patient compliance.