A COMPARISON OF BIFONAZOLE (BAY-H-4502) WITH CLOTRIMAZOLE INVITRO

Abstract

The antifungal activity of a new topical imidazole, bifonazole (BAY h 4502), was compared in vitro with that of clotrimazole (BAY b 5097) in tests with 67 pathogenic and commensal yeasts, 45 dermatophytes and 14 miscellaneous pathogenic fungi by an agar dilution method. Three media, Kimmig''s agar, Sabouraud''s agar and casein-yeast extract-glucose agar were used. Bifonazole was inhibitory for nearly all the yeasts tested including Candida albicans, C. parapsilosis and Torulopsis glabrata, with geometric mean minimal inhibitory concentrations (G-MIC) averaging 5 .mu.g ml-1 on all 3 media. Clotrimazole was the more active drug against these same species with G-MIC ranging from 0.25-2.10 .mu.g ml-1. Resuls with bifonazole were affected by choice of medium with Kimmig''s agar generally giving the lowest MIC; results with clotrimazole were also affected by choice of medium but to a lesser degree. In nearly all instances, bifonazole and clotrimazole were inhibitory for the dermatophytic fungi at concentrations of .ltoreq. 0.50 .mu.g ml-1 and clotrimazole was the more active drug. Choice of medium was not a factor with these latter fungi which included Epidermophyton, Trichophyton and Microsporum spp. Both drugs were active against species of Aspergillus (G-MIC, 3.18 .mu.g ml-1), Fusarium (G-MIC, 1.59-12.70 .mu. ml-1) and Scopulariopsis (G-MIC, 1.78 .mu.g ml-1); clotrimazole was the more active drug by factors of 2- to 4-fold on all 3 media. Bifonazole MIC varied with pH (maximal activity at pH 6.5) with selected yeasts when tested on Kimmig''s agar. Differences in results obtained with varying inoculum sizes for these same yeasts generally were unremarkable. With selected species of yeasts and dermatophytes, the ratio of minimal fungicidal to inhibitory concentrations was much lower for bifonazole than for clotrimazole.