Determination of Dexamethasone in Human Plasma by UPLC-MS/MS and Its Clinical Application

We aimed to develop an ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method to determine the concentration of dexamethasone (DXM) in human plasma. The column was an ethylene bridged hybrid C18 eluted with a gradient of 0.01% formic acid in acetonitrile-0.01% formic acid in water as the mobile phase at a flow rate of 0.4mL/min in electrospray ionization positive ion mode with multiple reaction monitoring. After tuning, the ion pair for quantification was DXM: m/z 393.03→237.02. DXM showed a good linear relationship within the range of 1.28~312.12ng/mL(r2=0.9988). The detection limit and lower limit of quantification were 0.50ng/mL and 1.00ng/mL, respectively. Relative standard deviations of intra-day and inter-day precision were <10.01%. Accuracy was within the range of 100.65%-107.82%. Extraction recovery was within the range of 80.90%-84.32%. The matrix effects ranged from 102.4% to 120.0%. Plasma samples remained stable before and after treatment under various conditions, with the relative error being within ±10%. Fetal immune mediated atrioventricular block induced by anti-SSA/Ro-positive or anti-SSB/La-positive mothers with Sjogren syndrome were clinically treated with corticosteroids, whereas the effect and security need to be testified. This is the first applied method in cases in which the mother is administered DXM orally. It was found that DXM exists in neonate plasma and that the DXM concentrations of plasma samples of the mother and neonate were 25.7ng/mL and 5.6ng/mL, respectively, with rough ratio being 5:1. The developed method is sensitive, efficient, and convenient to determine the concentration of DXM in plasma of mother and neonate so as to provide precise data for clinical application. © 2021, Editorial Board of Journal of Tianjin University(Science and Technology). All right reserved.