Combination of oral flucytosine and ketoconazole as therapy for experimental cryptococcal meningitis

Current therapy for cryptococcal meningitis often is ineffective, toxic, and inconvenient. Ketoconazole has been shown to penetrate into brain tissue of mice and cerebrospinal fluid of humans and to improve the course of human coccidioidal meningitis. Ketoconazole, flucytosine, and amphotericin B, alone and in two-drug combinations, were used to treat cryptococcal meningitis in mice injected intracranially with Cryptococcus neoformans. Mortality was assessed, and numbers of cryptococci in brain and liver were counted. By both of these parameters, the combination of flucytosine and ketoconazole produced results superior to those of either agent used alone. The standard combination of amphotericin B and flucytosine also showed an additive effect in this model. However, the combination of amphotericin B and ketoconazole consistently showed no additive effect. None of the combinations of drugs was antagonistic. Our results indicate a possible role for therapy with a combination of oral flucytosine and ketoconazole as part of the treatment for cryptococcal meningitis.