Voriconazole-d3 contains three deuterium atoms located on the β methyl group. It is intended for use as an internal standard for the quantification of voriconazole by GC- or LC-mass spectrometry. Voriconazole is a triazole, antifungal agent that inhibits a broad range of pathogenic yeasts, including Candida (MIC = 0.03-8 μg/ml), and filamentous fungi such as Aspergillus, Scedosporium, and Fusarium. Its inhibitory action results from its ability to inhibit the synthesis of ergosterol, the major sterol of the fungal cell membrane.