Ultrahigh-performance liquid chromatography-ultraviolet absorbance detection-high-resolution-mass spectrometry combined with automated data processing for studying the kinetics of oxidative thermal degradation of thyroxine in the solid state

• Published in: Journal of Chromatography A Vol. 1371; pp. 196 - 203
• Main Authors: Neu, Volker, Bielow, Chris, Reinert, Knut, Huber, Christian G.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 05.12.2014; Elsevier
• Subjects: Automated; Automation, Laboratory - methods; Availability; Bioinformatics; Biological and medical sciences; Chromatography; Chromatography, High Pressure Liquid - methods; Data processing; Degradation; Drug degradation; Electrospray ionization Orbitrap mass spectrometry; Hormones. Endocrine system; Kinetics; Mass Spectrometry - methods; Medical sciences; Oxidation-Reduction; Pharmacology. Drug treatments; Reaction kinetics; Spectroscopy; Stressing; Temperature; Thyroxine; Thyroxine - analysis; Thyroxine - chemistry; Ultrahigh-performance liquid chromatography; Ultraviolet Rays; Kinetics; Electrospray ionization Orbitrap mass spectrometry; Drug degradation; Bioinformatics; Ultrahigh-performance liquid chromatography; Thyroxine; Ultra performance liquid chromatography; Tandem mass spectrometry; Chemical analysis; Impurity; Aminoacid derivative hormone; Orbitrap; Electrospray; Bulk material; Ion trap; Oxidation; Pyrolysis; Automation; Coupled method; Data processing; Solid state; Ultraviolet detector; Thyroid hormone; Degradation product; Mass spectrometry
• ISSN: 0021-9673; 1873-3778
• DOI: 10.1016/j.chroma.2014.10.071

•Fast UHPLC method employing sub 2μm particles for rapid impurity profiling.•High-resolution Orbitrap mass spectrometry for structure elucidation.•Time-resolved analysis of impurity profiles to investigate degradation kinetics.•Automated bioinformatic processing and comparison of impurity profiles.•Mechanistic study of thyroxine degradation. Levothyroxine as active pharmaceutical ingredient of formulations used for the treatment of hypothyroidism is distributed worldwide and taken by millions of people. An important issue in terms of compound stability is its capability to react with ambient oxygen, especially in case of long term compound storage at elevated temperature. In this study we demonstrate that ultrahigh-performance liquid chromatography coupled to UV spectrometry and high-resolution mass spectrometry (UHPLC-UV-HRMS) represent very useful approaches to investigate the influence of ambient oxygen on the degradation kinetics of levothyroxine in the solid state at enhanced degradation conditions. Moreover, the impurity pattern of oxidative degradation of levothyroxine is elucidated and classified with respect to degradation kinetics at different oxygen levels. Kinetic analysis of thyroxine bulk material at 100°C reveals bi-phasic degradation kinetics with a distinct change in degradation phases dependent on the availability of oxygen. The results clearly show that contact of the bulk material to ambient oxygen is a key factor for fast compound degradation. Furthermore, the combination of time-resolved HRMS data and automated data processing is shown to allow insights into the kinetics and mechanism of impurity formation on individual compound basis. By comparing degradation profiles, four main classes of profiles linked to reaction pathways of thyroxine degradation were identifiable. Finally, we show the capability of automated data processing for the matching of different stressing conditions, in order to extract information about mechanistic similarities. As a result, degradation kinetics is influenced by factors like availability of oxygen, stressing time, or stressing temperature, while the degradation mechanisms appear to be conserved.