In situ Gels of Acylovir Nanoemulsions for Improved Delivery to the Eye

Background: Acyclovir, BCS Class III drug is commercially available as 3% w/w eye ointment for multiple applications. Acyclovir nanoemulsions can be proposed to reduce dose because of improved permeation characteristics. Further, the development of in situ ophthalmic gels can be advantageous to reduce the number of applications due to increased mucoadhesion and sustaining effect. Objective: The purpose of this study was the development and evaluation of nanoemulsions based in situ gels of Acyclovir (1% w/w) as potential ophthalmic delivery systems. Methods: Nanoemulsions of Acyclovir were developed by Phase Inversion Temperature method using Capmul MCM, stearyl amine and Kolliphor RH 40 as liquid lipid, charge inducer and surfactant, respectively selected on the basis of Acyclovir solubility in the oil phase and emulsification ability of surfactants. These nanoemulsions were further developed into in situ ophthalmic gels using gellan gum and Methocel K4M. Results: The developed gels showed a sustained effect in vitro release studies and improved goat corneal permeation in ex vivo studies when compared to marketed ointment. HET-CAM studies concluded the absence of irritation potential, while in vivo irritation study in Wistar rats showed the absence of erythema and swelling of eyes after visual inspection for 72 hours. Histopathological studies on isolated rat corneas showed no abnormalities in anterior corneal epithelium and corneal stroma without any epithelial hyperplasia. Acyclovir nanoemulsions based in situ ophthalmic gel showed increased corneal deposition and permeation in isolated rat eyes. Conclusion: The improved potential of developed ophthalmic gels was proven due to the reduced frequency of application compared to the marketed ointment in animal studies.