Antifungal activity of itraconazole compared with hydroxy-itraconazole in vitro

Microbroth dilution tests in vitro showed the same IC50 values for itraconazole and hydroxyitraconazole, within a mode a one dilution range of experimental error, for 90% of 1481 isolates of pathogenic fungi, representing 48 genera. Some 10-15% of Candida glabrata and Trichophyton mentagrophytes isolates were more susceptible to itraconazole than hydroxy-itraconazole. Replicate tests with bioassay marker strains of Candida kefyr and Candida albicans showed no susceptibility variations outside the mode +/- one dilution range. We conclude that few fungi differ substantially in their susceptibility to itraconazole and hydroxy-itraconazole.