A Rapid High-Performance LC-MS/MS Method for Therapeutic Drug Monitoring of Voriconazole, Posaconazole, Fluconazole, and Itraconazole in Human Serum

To achieve therapeutic efficacy and prevent toxicity simultaneously, therapeutic drug monitoring has been increasingly adopted for antifungal agents with narrow therapeutic indexes. We herein report the development and validation of an accurate, simple, fast, and cost-effective clinical test with high-performance LC-MS/MS to simultaneously quantify voriconazole, posaconazole, fluconazole, and itraconazole in human serum. Mixed with extraction solution and internal standard, 100 μL serum samples were centrifuged for protein precipitation. Diluted supernatant was injected onto a Phenomenex® Luna C8 (2) 50 × 2 mm (3 μm) column and was analyzed with a Prominence Shimadzu high-performance liquid chromatography (HPLC) system coupled with a SCIEX QTRAP 4000 mass spectrometer in a positive ionization mode with multiple reaction monitoring. The total analytical run time was 3 min. The assay is linear for voricoanzole (0.01-10 μg/mL), posaconazole (0.02-40 μg/mL), fluconazole (0.2-200 μg/mL), and itraconazole (0.02-20 μg/mL). The intraday CVs ranged from 1.9% to 3.8% (n = 20); the interday CVs ranged from 2.7% to 5.4% (n = 20). Method comparison study (n = 39 or 40) demonstrated good correlation with reference laboratories (R >0.99) with average biases ranging from -7.2% to 17.5%. The recoveries for each analyte were above 90%, and matrix effects ranged from 95% to 112%. The method is acceptable for routine therapeutic drug monitoring of these antifungal agents in clinical laboratories for better therapeutic outcome.