Comparison of the in vitro and in vivo activity of the bis-triazole derivative UK 49,858 with that of amphotericin B against Histoplasma capsulatum.

The antifungal activity of UK 49,858, a difluorophenyl bis-triazole derivative, was evaluated in vitro against seven strains of Histoplasma capsulatum and in vivo in AKR and C57BL/6 murine models of histoplasmosis. UK 49,858 had a lower toxicity for AKR and C57BL/6 mice than amphotericin B did. The therapeutic index of UK 49,858 was 4.3 for AKR mice and 7.1 for C57BL/6; with amphotericin B it was 2 for both mouse strains. Given orally, UK 49,858 compared favorably with amphotericin B given intraperitoneally in either AKR or C57BL/6 mice infected with H. capsulatum.