An ultra performance liquid chromatography-tandem mass spectrometry method for the therapeutic drug monitoring of isavuconazole and seven other antifungal compounds in plasma samples.


Toussaint B, Lanternier F, Woloch C, Fournier D, Launay M, Billaud E, Dannaoui E, Lortholary O, Jullien V.
J Chromatogr B Analyt Technol Biomed Life Sci. 2017 Jan 23;1046:26-33.


A new analytical method was developed for the routine Therapeutic Drug Monitoring of 8 antifungals compounds in 50μL of plasma: isavuconazole (ISZ), voriconazole (VRZ), posaconazole (PSZ), fluconazole (FCZ), caspofungin (CSF), flucytosine (5FC), itraconazole (ITZ) and its metabolite OH-itraconazole (OH-ITZ). After adding 50μL of the internal standard, which consisted in a mixture of the deuterated isotopes of the quantified compounds, the sample treatment consisted in a simple protein precipitation with 400μL of acetonitrile. Five microliters of the supernatant were directly injected into the chromatographic system. The chromatographic separation was performed with a Waters C18-BEH column and a mobile phase consisting in a mixture of water and acetonitrile, both containing 0.1% of formic acid. The total run time was 3min and the detection of the analytes was performed by electrospray ionization in a positive mode using selected reaction monitoring. Intra and inter-day precision and inaccuracy were <15% over the calibration ranges that were determined according to their clinical relevance: 0.20-20.0mg/L for ISZ, VRZ, PSZ, ITZ, and OH-ITZ; 0.50-50.0mg/L for FCZ and CSF; 2.00-200mg/L for 5FC. This simple and fast method was found suitable for routine therapeutic drug monitoring.