Hydroxy itraconazole (OH-ITZ) is an active metabolite of the antifungal agent itraconazole . Itraconazole is metabolized by the cytochrome P450 isoform 3A4 (CYP3A4) to form hydroxy itraconazole. Hydroxy itraconazole exhibits in vitro antifungal activity (MIC = 0.019, 0.078, and 0.078 mg/ml against C. albicans, A. fumigatus, and C. neoformans, respectively). Plasma concentration of hydroxy itraconazole is directly correlated to that of the parent compound and is used as an indicator of prophylaxis for fungal infections.