Development, Validation, and Clinical Application of an Ultra-High-Performance Liquid Chromatography Coupled With Tandem Mass Spectrometry Method for the Determination of 10 Antituberculosis Drugs in Human Serum

Introduction: Linezolid, moxifloxacin, rifapentine, rifabutin, cycloserine, clofazimine, bedaquiline, levofloxacin, prothionamide, and ethionamide are commonly used second-line antituberculosis (anti-TB) drugs. To support therapeutic drug monitoring in regular clinical practice, the authors sought to develop a method based on ultra-high-performance liquid chromatography coupled with tandem mass spectrometry (UHPLC-MS/MS) that would allow for the simultaneous quantification of multiple second-line anti-TB drugs in human serum. Methods: Analytes were extracted from human serum by protein precipitation. UHPLC-MS/MS was performed using a gradient at a flow rate of 0.3 mL/min, and each sample was taken for 7.5 minutes. The mass spectrometry scanning mode used was electrospray ionization with multiple reaction monitoring in the positive mode. Results: Validation showed that endogenous substances in the sample did not interfere with the assay, and the relationship between X and Y was highly linear, with a coefficient of determination (R-2) >0.9954 for each curve. The accuracy (85.0%-114.7%) and precision (intraday: 0.27%-9.32%; interday: 0.20%-7.66%) were less than 15.0%, and the internal standard-normalized matrix effects were consistent (coefficient of variation <= 4.40%). The analytes were stable in the final extract and human serum under various storage conditions (recovery: 87.0%-115.0%). The clinical applicability of the method was demonstrated by quantitative determination of analytes in serum samples obtained from patients with TB. Reproducibility of the drug concentrations measured in clinical samples was confirmed by incurred sample reanalysis. Conclusions: A simple and reliable analytical method was developed and validated for the simultaneous determination of 10 anti-TB drugs in human serum using UHPLC-MS/MS. Quantitation of anti-TB drugs in clinical samples confirmed that the assay is suitable for therapeutic drug monitoring in regular clinical practice.