High-throughput simultaneous quantification of five azole anti-fungal agents and one active metabolite in human plasma using ultra-high-performance liquid chromatography coupled to tandem mass spectrometry

Objectives: For patients with hematological malignancy, triazole antifungal agents such as fluconazole (FLCZ), itraconazole (ITCZ), voriconazole (VRCZ), posaconazole (PSCZ) and isavuconazole (ISCZ) are often used for prophylaxis of deep mycosis. Since these azoles exhibit large pharmacokinetic variability, dose adjustment by therapeutic drug monitoring is recommended for some azoles. This study aimed to develop and validate a novel method for simultaneous determination of plasma concentrations of FLCZ, ITCZ, VRCZ, PSCZ, ISCZ and ITCZ-OH, an active metabolite of ITCZ, using ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS). Design & methods: A high-throughput solid-phase extraction method using 96-well MCX mu Elution Plate was selected as the pretreatment procedure. Results: The calibration curves for FLCZ, ITCZ, ITCZ-OH, VRCZ, PSCZ and ISCZ showed good linearity (backcalculation of calibrators: relative error < 15% [LLOQ: < 20%]) over wide ranges of 100-100000, 20-20000, 40-40000, 20-20000, 5-5000 and 50-50000 ng/mL, respectively. The validation results of all six drugs fulfilled the criteria of the guidance for bioanalytical method validation of the US Food and Drug Administration for within-batch and batch-to-batch precision and accuracy. The extraction recovery rates were good at >= 74.9%, and almost no matrix effects were found for all the drugs. The trough (10 h post-dose in 1 patient on PSCZ) drug concentrations in patients with hematologic malignancy who received oral FLCZ, ITCZ, VRCZ or PSCZ were quantified using the method developed. The measurements for all samples were within the ranges of the calibration curves, demonstrating the feasibility of clinical application of the novel method. Conclusions: We have succeeded in developing a novel high-throughput method using UHPLC-MS/MS for simultaneous quantification of plasma concentrations of FLCZ, ITCZ, ITCZ-OH, VRCZ, PSCZ and ISCZ.