Chemotherapeutic activity of 5-fluorocytosine and amphotericin B against Candida albicans in mice.

The effect of treatment with combinations of the two antifungal agents, 5-fluorocytosine (5-FC) and amphotericin B (AB), against systemic Candida albicans infections in mice was investigated. Graded doses of the single substances and of combinations of the drugs were administered daily for 21 days. The 50% curative dose (CD(50)) values were calculated on the basis of the presence or absence of C. albicans in cultures prepared from the kidneys of animals that succumbed during the experimental period or were sacrificed at the termination of the experiments. Overall, when graded doses of AB were administered in the presence of a constant, inactive dose of 5-FC (approximately one-half to one-fourth the CD(50) of 5-FC), the CD(50) values for AB were lower than those for amphotericin B alone. Similarly, the CD(50)s for 5-FC were reduced when AB was administered at a constant dose equal to one-half to one-fourth the CD(50) of AB alone. In no instance was there evidence of antagonism.