Stress degradation study on entrectinib and characterization of its degradation products using HRMS and NMR

Entrectinib is a potent inhibitor of receptor tyrosine kinases and anaplastic lymphoma kinase. It is designated as an orphan drug. There exists no report of comprehensive degradation profiling of the drug in the literature. Therefore, the present study focused on establishment of its stress degradation chemistry under hydrolytic (acidic, alkaline, neutral), oxidative (H₂O₂), photolytic and thermal conditions. For the purpose, the stressed solutions were subjected to HPLC studies on a C8 column by employing a gradient elution method, in which acetonitrile and 10 mM ammonium acetate were used as the mobile phase components. The results showed that entrectinib was labile to alkaline, H₂O_2, and photoneutral conditions in the solution state. The drug proved to be stable under acidic, solid-state photolytic, and thermal conditions. A total of sixteen degradation products were formed, which were characterized with the help of high resolution mass spectrometry, and in one case additional help was taken of 1D and -2D NMR data. The knowledge of the structures of the degradation products helped in establishment of degradation pathway of the drug and the involved mechanisms. Also, the toxicity profile of the drug and its degradation products was predicted using ADMET Predictor™ software, which indicated mutagenic potential of atleast five degradation products.