Itraconazole in pityriasis versicolor: ultrastructural changes in Malassezia furfur produced during treatment.

Twenty-eight patients with pityriasis versicolor were treated orally with 200 mg of itraconazole per day in an open, randomized comparison of five-day and seven-day treatment regimens. The morphologic changes in Malassezia furfur produced by treatment were confirmed by studies with transmission and scanning electron microscopy. The clinical results showed that seven days of treatment were more effective than five days. Transmission electron microscopy revealed cytopathic changes in the fungus at the end of treatment, intracellular necrosis being complete within seven to 28 days. Cell-surface alterations detected by scanning electron microscopy developed more slowly--maximal changes were observed 14 days after the beginning of treatment. One patient developed nausea during treatment; no other adverse effects were attributed to the drug.