Combination therapy of experimental histoplasmosis and cryptococcosis with amphotericin B and ketoconazole.

Combinations of amphotericin B and ketoconazole had an additive effect in vitro against Histoplasma capsulatum and Cryptococcus neoformans; ketoconazole combined with flucytosine exerted an indifferent effect against C. neoformans. In vivo studies in athymic nude (nu/nu) mice and their heterozygous (nu/+) littermates demonstrated that treatment with the ketoconazole-amphotericin B combination resulted in longer survival of mice with cryptococcosis than did treatment with ketoconazole plus flucytosine. However, mice given ketoconazole plus amphotericin B did not survive significantly longer than those given amphotericin B alone (cryptococcosis) or ketoconazole alone (histoplasmosis). Combination chemotherapy with ketoconazole and amphotericin B may offer a modest therapeutic advantage over therapy with either drug alone.