ABSTRACT
BACKGROUND AND AIM: Dexamethasone is one of the most potent glucocorticoid. It is used in the various medical conditions such as multiple sclerosis, allergies, inflammation, asthma, dermatitis and shock. Recently, dexamethasone has been found to be beneficial in patients with COVID-19 pneumonia requiring supplemental oxygen or mechanical ventilation. It can cause serious adverse effects such as adrenal suppression, hyperglycemia, and cardiac arrhythmia. Therefore, monitoring of dexamethasone levels is important. Our aim in this study is to develop an LC-MS/MS method for dexamethasone. METHODS: Dexamethasone was detected with ABSciex API 3200 tandem mass spectrometery in positive electrospray ionization mode. The selected ion transitions for dexamethasone and internal standard were m/z 289.5/97.3 and m/z 339.1/113.2, respectively. Briefly, 100 μL of internal standard (17-hydroxyprogesterone-d8) and 4 mL of diethylether were added to 250 μL of sample, and vortexed for 1 minute, then centrifuged at 4000 g for 10 minutes. The supernatant was taken into tubes and evaporated at 40 °C under nitrogen gas. The residues were dissolved in 200 μL of methanol:water (1:1, v/v%) and 25 μL was injected. RESULTS: The calibration curve was linear between 1.95 and 2000 ng/mL (r2>0.99). The limit of quantitation for dexamethasone was 1.95 ng/mL. Total run time was 5 minutes. Intra- and inter-assay imprecision values were less than 9%. The mean extraction recovery was 92.8%, and the matrix effect ranged from 3.6% to 9.8%. CONCLUSIONS: A sensitive and reproducible tandem mass spectrometry method was developed for dexamethasone. The method can be used in the analysis of dexamethasone.