Mechanism of action of efinaconazole, a novel triazole antifungal agent.

The mechanism of action of efinaconazole, a new triazole antifungal, was investigated with Trichophyton mentagrophytes and Candida albicans. Efinaconazole dose-dependently decreased ergosterol production and accumulated 4,4-dimethylsterols and 4α-methylsterols at concentrations below its MICs. Efinaconazole induced morphological and ultrastructural changes in T. mentagrophytes hyphae that became more prominent with increasing drug concentrations. In conclusion, the primary mechanism of action of efinaconazole is blockage of ergosterol biosynthesis, presumably through sterol 14α-demethylase inhibition, leading to secondary degenerative changes.