Activity of the triazole SCH 56592 against disseminated murine coccidioidomycosis

SCH 56592 (SCH) is a new triazole antifungal with a broad spectrum of activity, In vitro susceptibility testing against five strains of Coccidioides immitis revealed MICs from 0.39 to 3.13 mu g/ml and minimal fungicidal concentrations from 1.56 to 3.13 mu g/ml. A murine model of systemic coccidioidomycosis was established in female CD-I mice, Groups received either no treatment or oral therapy with fluconazole at 10 or 100 mg/kg of body weight; itraconazole at 10 or 100 mg/kg; SCH at 0.5, 2, 10, or 25 mg/kg; or its methylcellulose diluent alone, Therapy began 2 days postinfection and continued once daily for 19 days, Surviving mice were euthanized 49 days postinfection, and infectious burdens were determined by culture, All drugs were superior to no-treatment or diluent-treatment controls (P < 0.001) in prolonging survival hut were not significantly different from one another, Itraconazole at 100 mg/kg was superior to fluconazole in reduction of CFU in the spleen, liver, and lung (P < 0.01 to 0.001), SCH at 0.5 mg/kg was superior to either fluconazole or itraconazole at 10 mg/kg in reduction of CFU in all three organs (P < 0.05 to 0.001). SCH at 2 mg/kg was not significantly different from itraconazole at 100 mg/kg in all three organs. SCH at 10 and 25 mg/kg was superior to either dose of fluconazole or itraconazole in all three organs (P < 0.05 to 0.001), In terms of reduction of CFU, SCH was greater than or equal to 200-fold as potent as fluconazole and greater than or equal to 50-fold as potent as itraconazole. There was a clear dose-responsive relationship for SCH in each of the organs, It is noteworthy that SCH effected cures (no detectable C. immitis in any organ) in 1 of 9, 6 of 10, or 9 of 9 surviving mice in animals given 2, 10, or 25 mg/kg, respectively, Neither fluconazole nor itraconazole cured any survivor, SCH has potent, fungicidal activity in vivo against C. immitis. It should be considered for clinical trials in patients with coccidioidomycosis.