NB-002, a Novel Nanoemulsion with Broad Antifungal Activity against Dermatophytes, Other Filamentous Fungi, and Candida albicans

Abstract

ABSTRACT NB-002 is an oil-in-water emulsion designed for use for the treatment of skin, hair, and nail infections. The activity of NB-002 was compared to the activities of the available antifungal drugs against the major dermatophytes responsible for cutaneous infections, Trichophyton rubrum , Trichophyton mentagrophytes , Epidermophyton floccosum , and Microsporum spp., as well as 12 other genera of filamentous fungi. NB-002 consistently displayed fungicidal activity against all dermatophytes. The comparator compounds were either fungistatic or fungicidal, and for some strain-drug combinations, tolerance was observed. Assessment of the development of spontaneous resistance to NB-002 in different dermatophyte species yielded few stably resistant mutants. For filamentous nondermatophyte fungi, the MIC range varied from 0.06 to 0.5 μg/ml for Alternaria spp. to 2 to 8 μg/ml for Paecilomyes spp. NB-002 had activity against both azole-susceptible and -resistant Candida albicans yeast isolates, with MIC 90 s of 2 μg/ml, respectively, and minimum fungicidal concentrations at which 90% of isolates are inhibited of 4 and 8 μg/ml, respectively. The kinetics of the fungicidal activity of NB-002 against T. rubrum isolates were compared to those of the other antifungal drugs. NB-002 killed both mycelia and microconidia even when the fungal forms were dormant or not actively growing. Electron micrographs of mycelia and spores treated with NB-002 showed the significant disruption of the fungal structure. The in vitro broad coverage of NB-002 against filamentous fungi, dermatophytes, and C. albicans , as well as its rapid fungicidal activity, warrants further investigations to ascertain if NB-002 would be useful for the treatment of cutaneous mycoses.