Comparison of the in Vitro Antifungal Activities of Miconazole and a New Imidazole, R41,400

Abstract

R41,400 is a recently synthesized, water-soluble imidazole. Its antifungal properties were compared in vitro with those of miconazole using an agar dilution procedure and 175 isolates of human fungal pathogens. The filamentous forms of Histoplasma capsulatum and Blastomyces dermatitidis were inhibited by ⩽2 µg of either drugjml; Coccidioides immitis was inhibited by ⩽0.5 µg of R41,400/ml. Among the yeasts tested, Cryptococcus neoformans and Candida parapsilosis were the most susceptible to the two drugs, whereas Candida albicans and Candida tropicalis were the least susceptible; 0.5 µg of either drug(ml was inhibitory for 90%–100% of tested isolates of C. neoformans but for only ⩽20% of isolates of C. albicans, C. tropicalis, and Torulopsis glabrata. Both drugs were inhibitory for most isolates of Trichophyton and Microsporum species at concentrations of ⩽4 µg/ml; Epidermophyton floccosum was uniquely susceptible to both drugs.