A VALIDATED LIQUID CHROMATOGRAPHY-ELECTROSPRAY IONIZATION-MASS SPECTROMETRY/MASS SPECTROMETRY METHOD FOR THE QUANTIFICATION OF UPADACITINIB IN BIOLOGICAL MATRICES: APPLICATION TO PHARMACOKINETICS IN HEALTHY RABBITS

Objectives: Quantification of upadacitinib in biological matrices using pharmacokinetic investigations in healthy rabbits requires a validated LC-ESI-MS/MS technique. Methods: The processed samples were separated using a 3.5µm symmetric C18 column (100mm×4.6 mm) with a mobile phase consisting of acetonitrile, methanol, and 0.1% formic acid at a volume ratio of 50:30:20% V/V. The flow rate into the column was adjusted to 0.70 mL/min. Results: In multiple reaction monitoring mode, the drug and erlotinib internal standards were assessed by watching the transitions of m/z 381.3→72.08 and m/z 394.29→278.19, respectively. Results showed that the linearity equation (y= 0.00418 × x + 0.00161) and the correlation coefficient (R2) were 0.9987 and 0.9987, respectively. For the quality control samples (1.2, 3.36, 97.7, and 146.5 ng/mL), the %RSD of intra- and inter-day accuracy of the proposed approach ranged from 2.62 to 4.29%. In healthy rabbits, the medication had an average AUC last of 98.379 ± 9.845 h*ng/mL and a Cmax of 54.55 ±4.6ng/mL, according to bioavailability studies. Conclusion: The proposed method was successfully applied to pharmacokinetic studies following oral administration of the drug in healthy rabbits.