Separation and characterization of degradation impurities of upadacitinib by liquid chromatography and high resolution mass spectrometry

Upadacitinib is an oral Janus Kinase inhibitor used for the treatment of rheumatoid arthritis. This research focuses on the forced degradation study of upadacitinib and the characterization of its degradation impurities. Upadacitinib was subjected to various degradation conditions such as hydrolysis (acid, base, neutral), oxidation, thermal, and photolysis according to International Council for Harmonisation guidelines. Twelve degradation impurities of upadacitinib were observed under oxidation (H₂O₂, AIBN, Fenton’s reagent) and photolysis (UV light). Zeneth software was used to predict the in silico degradation profile. High-performance liquid chromatography was used to separate the observed degradation impurities with ammonium formate (pH 3.63) and acetonitrile as mobile phases on an Agilent Zorbax Eclipse plus C18 column (4.6 × 250 mm, 5 µm). The separated degradation impurities were characterized by using high resolution mass spectrometry. The accurate masses obtained from LC-HRMS/MS were used to determine the structures of all the degradation impurities. A suitable mechanism for the formation of degradation impurities was proposed. DEREK Nexus and SARAH Nexus were used for the in silico toxicity and mutagenicity assessments.