In vitro activity: Fluconazole in combination with amphotericin B (AmB) has a synergistic effect on C. albicans planktonic cells but does not alter AmB activity against biofilms. Fluconazole and caspofungin have an antagonistic effect against biofilms but not with planktonic cells. Fluconazole-mediated membrane perturbation (due to inhibition of ergosterol biosynthesis) increases calcineurin inhibitor intracellular concentrations. Fluconazole treatment significantly reduces levels of ergosterol within the cell in C. albicans planktonic cells, leading to cell membrane perturbation. Fluconazole activity is less sensitive to acidic medium than is that of ketoconazole. Fluconazole is approximately 16-fold less active than ketoconazole against 35 representative isolates of C. albicans at physiologic pH. Fluvastatin, a cholesterol-lowering drug, exhibits minimal activity (MICs of 64 to>128 mg/mL) against Candida species and Cryptococcus neoformans. Fluconazole combined with itraconazole exhibits potent activities against C. albicans, C. tropicalis, C. parapsilosis, and C. neoformans, including flucon- azole-resistant strains of C. albicans and C. tropicalis.