4-(4-(4-(4-(((3R,5R)-5-((1H-1,2,4-triazol-1-yl)methyl)-5-(2,4-difluorophenyl)tetrahydrofuran-3-yl)methoxy)phenyl)piperazin-1-yl)phenyl)-2-((2S,3S)-2-hydroxypentan-3-yl-4,4,5,5,5-d5)-2,4-dihydro-3H-1,2,4-triazol-3-one

Posaconazole-d₅ is intended for use as an internal standard for the quantification of posaconazole by GC- or LC-MS. Posaconazole is a broad-spectrum triazole antifungal agent active against various yeasts and molds, including Aspergillus, Candida, Fusarium, and Zygomycetes.¹ Posaconazole inhibits the growth of fungi by inhibiting the lanosterol 14α-demethylase enzyme (IC₅₀s = 7-200 nM), which results in a disruption in the synthesis of ergosterol , a key sterol necessary for fungal cell membrane integrity and for the function of certain membrane-bound proteins.²

1. Herbrecht, R., Nivoix, Y., Fohrer, C., et al. Management of systemic fungal infections: Alternatives to itraconazole J. Antimicrob. Chemother. 56(Suppl 1),i39-i48(2005).
2. Munayyer, H.K., Mann, P.A., Chau, A.S., et al. Posaconazole is a potent inhibitor of sterol 14α-demethylation in yeasts and molds Antimicrob. Agents Chemother. 48(10),3690-3696(2004).