Activity of triazole derivatives against Pityrosporum orbiculare in vitro and in vivo.

The in vitro antimycotic activity and the in vivo antimycotic activity (in a rabbit model) of itraconazole against P. orbiculare were compared to the corresponding activities of ketoconazole. Fluconazole's in vitro antimycotic activity and in vivo antimycotic activity against P. orbiculare were tested in the same models. The MIC values of itraconazole against P. orbiculare were 0.1-0.2 micrograms/ml compared to 0.02-0.05 micrograms/ml for ketoconazole. For fluconazole, the MIC values were 12.5-50.0 micrograms/ml against P. orbiculare. In a rabbit model, orally administered itraconazole (5 mg/kg) afforded protection against experimental pityriasis (tinea) versicolor in four out of five rabbits. Ketoconazole (1 mg/kg) was effective in all four animals. The in vivo results with fluconazole were in contrast to its low in vitro activity. Fluconazole (5 mg/kg) afforded protection against experimental pityriasis (tinea) versicolor in five out of six animals.