| Summary: | Objective To develop liquid chromatography-tandem mass spectrometry (LC-MS/MS) for the content determination of voriconazole (VRCZ) and its N-oxide (VNO) in human plasma, and to apply it to clinical samples. Methods Ketoconazole was used as the internal standard (IS). The plasma samples were treated with methanol to precipitate protein and analyzed by HPLC-MS/MS. The detection was accomplished with electrospray ionization (ESI) operated in positive ionization mode, and ion reaction pairs were selected to be m/z350.1→m/z127.0 (VRCZ), m/z366.1→m/z224.0 (VNO) and m/z531.0→m/z82.1 (Ketoconazole). Chromatographic separation had been achieved on Inertsil ODS-3 (50/2.1) with methanol-10 mmol/L ammonium acetate (90:10) as the mobile phase. Plasma concentrations of VRCZ and VNO in 23 patients were determined. Results Both VRCZ and VNO were linear (r>0.999) over the concentration ranges of 0.4~10.0 μg/mL, inter- and intra-batch relative standard deviations (RSDs) and matrix effect were all less than 15%. The 2 compounds remained stable during sample storage and handling progress. Plasma concentrations of VRCZ in 23 patients ranged from 0.4 to 14.3 μg/mL, and those of VNO ranged from 0.5 to 7.2 μg/mL. Significant variance was found among these patients. Conclusion LC-MS/MS is simple, quick and sensitive for detection of VRCZ and VNO, and can be used for drug monitoring in clinical practice.
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