Simultaneous determination of voriconazole and its metabolites in human plasma by capillary electrophoresis with cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography

This study presents a highly efficient analytical approach combining cation-selective exhaustive injection and sweeping micellar electrokinetic chromatography with photodiode array detection for the simultaneous determination of voriconazole (VRC) and its key metabolites, voriconazole <i>N</i>-oxide (VNO) and hydroxy-voriconazole (V-OH), in human plasma. The method utilizes a precisely optimized capillary electrophoresis system with the following conditions: an uncoated fused-silica capillary (30 cm, 50 μm I.D.) filled with phosphate buffer (125 mM, pH 2.5) containing 15% (v/v) acetonitrile and 10% (v/v) propanol, followed by a high-conductivity buffer zone (100 mM phosphate, pH 2.5, 8.3 kPa, 99.9 s). After electrokinetic injection (10 kV, 600 s) of cationic analytes, separation was achieved under -20 kV using phosphate buffer (50 mM, pH 2.5) containing 200 mM sodium dodecyl sulfate. Detection was set at 214 nm. This optimized method demonstrated excellent sensitivity, with a detection limit (<i>S</i>/<i>N</i> = 3) of 0.01 μg mL^-1 for all analytes. The sensitivity was increased by 200 times compared to the conventional MEKC method. The calibration curves showed good linearity, with correlation coefficients exceeding 0.9995 over the ranges of 0.1-10.0 μg mL^-1 for VRC, 0.05-5.0 μg mL^-1 for VNO, and 0.05-1.0 μg mL^-1 for V-OH. Precision and accuracy assessments revealed relative standard deviations (RSDs) and relative errors (REs) of less than 7.2% and 5.2%, respectively. This method has been successfully applied to real plasma samples from patients. It can provide more accurate drug exposure information to assist VRC dosage adjustments, thus improving VRC treatment, and can also be applied in VRC pharmacokinetic studies.