Development of amphotericin B nanosuspensions for fungal keratitis therapy: effect of self-assembled γ-cyclodextrin

Abstract

Fungal keratitis is one of the major causes in loss of vision and blindness. Amphotericin B (AmB) is the first-line treatment of keratitis caused by Candida spp. and related fungi. Due to its high molecular weight and low aqueous solubility, it hampers the ocular bioavailability. It is well-known that γ-cyclodextrin (γCD) can enhance AmB solubility. The aim of this study was to investigate the effect of the additives on γCD solubilization of AmB and develop AmB eye drop nanosuspensions. 0.18% (w/v) AmB nanosuspensions containing either 0.25% (w/v) chitosan or 0.10% (w/v) phospholipids (PL) in aqueous γCD eye drop medium were prepared by using high pressure homogenization technique. Physicochemical properties, in vitro mucoadhesive, in vitro permeation, degree of AmB aggregation, hemolytic activity and in vitro antifungal test were determined. The physicochemical properties of the nanosuspensions containing AmB/γCD nanoaggregates were in the acceptable range. The particle size of all formulations was in nanometer range. The degree of aggregation was less than 2.0 that meant the drug was not in the aggregate form when solubilized in γCD. These formulations demonstrated relatively low hemolytic activity and effectively improved the antifungal activity. AmB/γCD nanosuspension stabilized by 0.10% (w/v) PL is the promising formulation for further studies due to that it was excellent physical appearance, had mucoadhesive property, enhanced in vitro permeation, had low toxicity and improved the antifungal activity.