Validation of enantioseparation and quantitation of an active metabolite of abrocitinib in human plasma.

Aims: A chiral HPLC-MS/MS method for quantitation of an active metabolite (M2) of abrocitinib was validated in human plasma. Methods: Protein precipitation extraction and normal phase LC with baseline separation of five analytes (abrocitinib; isomeric metabolites M1, M2, M3 and M4) were achieved followed by mass spectrometric quantitation of M2 using positive-mode APCI. Results: With a 5-5000 ng/ml assay range using 100 μl K ₂ EDTA aliquot, the assay provided short (17-min) runtime and robust separation up to approximately 330 injections on one column. Interday and intraday accuracy ranged from -6.80% to 13.4%; between-day and within-day precision was ≤10.4%. Conclusion: The method was used in multiple clinical studies, with excellent run passing rate and incurred sample reproducibility.