Nystatin nanosizing enhances in vitro and in vivo antifungal activity against Candida albicans

Abstract

In this study, we developed a nanoparticulate nystatin formulation and performed a comparative evaluation against a commercial nystatin preparation of its in vitro and in vivo antifungal activities. A nystatin nanosuspension was prepared from a commercially available suspension by wet-media milling. The nanosuspension was characterized for particle size by laser diffraction and assayed for content by HPLC. Its in vitro activity was evaluated against Candida albicans strains SC5314 and LAM-1 (12.5-5000 μg/mL) using an agar plate assay and its in vivo efficacy was evaluated using a murine model of oral candidiasis. Briefly, DBA/2 mice were immunosuppressed with cortisone acetate, orally infected with C. albicans strain LAM-1, and treated for 14 days with conventional nystatin suspension, nystatin nanosuspension or saline control. Efficacy endpoints were oral fungal burden, mouse survival and organ histopathology. A single-dose pharmacokinetic study was also performed. The median particle size of the nystatin suspension was reduced from 6577 to 137 nm. The HPLC assay demonstrated a nystatin content of 98.7% ± 0.8% of the label claim. In vitro activity was superior to that of the conventional nystatin suspension at 100-5000 μg/mL concentrations. Beginning on day 3 of treatment, lower oral burdens of C. albicans were found in the nanosuspension group compared with the suspension and control groups. Mouse survival was also superior in the nanosuspension group. No systemic absorption was observed. Taken together, these data reveal that nanonization of nystatin provides a novel approach to enhancing its efficacy in the treatment of oral candidiasis.