Posaconazole is a broad-spectrum, second generation, triazole compound with antifungal activity. Posaconazole is a sterol C14ɑ demethylase inhibitor (IC50: 0.25 nM). Posaconazole strongly inhibits 14-alpha demethylase, a cytochrome P450-dependent enzyme.

Inhibition of 14-alpha-demethylase prevents the conversion of lanosterol to ergosterol, an important component of the fungal cell wall. Inhibition of ergosterol synthesis changes the fungal cell membrane composition and integrity, alters membrane permeability, and eventually leads to fungal cell lysis. Compared to other azole antifungals, posaconazole is a significantly more potent inhibitor of sterol 14-alpha demethylase. Posaconazole is the most advanced candidate for the treatment of Chagas disease. Posaconazole has entered in phase II clinical trial in the treatment of mycoses.