Water Soluble Chitosan Mediated Voriconazole Microemulsion as Sustained Carrier for Ophthalmic Application: In vitro/Ex vivo/In vivo Evaluations

Abstract

Background: Voriconazole (VCZ) is a lipophilic candidate, effective against fungal infections like ocular keratitis and endopthalmitis. Objective: The purpose to develop, optimize and characterize voriconazole microemulsion as sustained medication for ophthalmic application. Methods: The pseudo-ternary phase diagrams were developed using oleic acid, isopropyl myristate and isopropyl palmitate (oil phases), tween 80 (surfactant), propylene glycol (co-surfactant), distilled water (aqueous phase) and modified chitosan (Mod.CH) as mucoadhesive polymer. The optimum composition of oil, Smix and water was selected on the basis of phase diagrams and as mucoadhesive polymer Mod.CH was used in the formulations. All the formulations were evaluated for thermodynamic stability/dispersibility, physicochemical parameters (droplet size, polydispersity index, zeta potential, drug content, viscosity, pH and conductivity), in vitro, ex vivo and in vivo studies. Results: All formulations showed droplet size below 250 nm, positive zeta potential and polydispersity index below 0.5. The in vitro drug release study performed on selected formulations showed maximum sustained release than marketed formulation. The in vitro transcorneal permeation experiment of formulations suggests that optimized formulations showed better permeation. The selected formulation of voriconazole microemulsion was able to produce maximum antifungal activity against Candida albicans when compared to marketed formulation. In vivo study performed on rabbit eyes, found more drug concentration in aqueous humor of optimized formulation; the AUC0→t of IPMVM-11 was approximately 6.84-fold higher than VOZOLE and efficiently enhanced the corneal bioavailability. Conclusion: The modified chitosan based on voriconazole loaded microemulsion was promising novel carrier for sustained action in ophthalmic medication.