A MICROEMULSION SYSTEM FOR CONTROLLED CORNEAL DELIVERY OF TIMOLOL

Abstract

This research was aimed to formulate and characterize microemolsion systems as an ocular delivery system of timolol for treatment of glaucoma. Methods:microemulsion(ME) formulations were prepared by mixing of appropriate amount of surfactants including Tween 80 and Labrasol , co-surfactant such as propylene glycol (PG) and oil phase including isopropyl myristate – Transcutul P (10:1 ratio). The prepared MEs were evaluated regarding their particle size, stability, scanning electron microscopy (SEM), release and permeation of the drug through rabbit cornea. Results: The results showed that the maximum oil was incorporated in ME system that was contained surfactant to co-surfactant ratio (Km) of 4:1.The mean droplets sizes of ME formulations were in the range of 2.48-46.2 nm .Drug release profile showed that 13.5% of the drug released in the first 8 hours of experiment. Also, micellar structure was seen in the SEM photographs of the MEs .Conclusion: characterization, physicochemical properties and in vitro release and permeation were dependent on the contents of S+C (surfactant+cosurfactant) , water and oil in formulations. Also, ME-8may be preferable for ocular timolol formulation