Miconazole in coccidioidomycosis. I. Assays of activity in mice and in vitro.

Administration of miconazole to mice infected with Coccidioides immitis prevented death in all cases; the infecting doses killed 60%-100% of the untreated animals. The drug's anticoccidioidal influence was also demonstrated by its capacity to limit fungal proliferation in the lungs. The endospore phase of C. immitis, which predominates in lesions, was more susceptible to miconazole than were the saprophytic arthrospore and mycelial phases. The drug was lethal to endospores in vitro in the presence or absence of human plasma, but plasma decelerated the rate of killing. A sensitive quantitative assay (using endospores) for the drug in plasma was developed, and the inefficacy of determining the sensitivity of strains with mycelia was demonstrated.