Formulation and evaluation of Acyclovir niosomes for ophthalmic use

Ahmed N. Allam, Safaa S. El gamal, Viviane F. Naggar

Abstract
Objective: is to prepare, evaluate and characterize ophthalmic niosomes of the antiviral drug, Acyclovir. Methods: Niosomes are prepared using two different methods namely: film hydration method (FHM) and reverse phase evaporation method (REV). Evaluation is achieved by characterization of the prepared niosomes through particle size and electron transmission microscopic analysis. Corneal permeation studies, using rabbit cornea are also performed. The study also includes qualitative ocular irritation testing, as well as, the physical stability of niosomes stored at 4ο and 25οC.Results: Particle size distribution studies revealed that formulations prepared without cholesterol, showed the smallest particle size. However, increased particle size was obtained by increasing cholesterol molar ratio, using FHM and in formulations prepared using Span 60. The data obtained from corneal permeation studies showed that the cumulative amount permeated from most niosomal formulations was lower than that from drug solution, except with those corresponding to cholesterol: surfactant molar ratio 1:1. Corneal hydration studies showed no corneal damage. Storage for one month showed that niosomes were more stable at 4οC than at 25 οC. Conclusion: it is possible to develop a safe and physiologically active topical niosomal formulation of Acyclovir. The developed formulations can form a cost effective treatment plan, which is especially important in the treatment of Herpes simplex keratitis that represents a severe disease and is a common cause of blindness.

Key words: Acyclovir, niosomes, permeation, ocular, stability