Pyrotinib in vitro metabolite profiling via rat, dog and human hepatocytes using liquid chromatography–quadrupole/orbitrap mass spectrometry.

Rationale: Pyrotinib is an irreversible EGFR/HER2 inhibitor that has shown antitumor activity and tolerance in the treatment of breast cancer. Studies focused on its metabolic pathways and major metabolites are insufficient. In the evaluation of drug safety and therapeutic use, metabolite characterization is critical. The metabolism of pyrotinib in vitro was studied utilizing rat, dog and human hepatocytes in this study. Methods: Pyrotinib (10 μM) was incubated with hepatocytes in Williams' E medium. The metabolites were examined and profiled using ultrahigh‐performance liquid chromatography coupled with quadrupole/orbitrap high‐resolution mass spectrometry. The metabolite structures were deduced by comparing their precise molecular weights, fragment ions and retention times with those of the parent drug. Results: A total of 16 metabolites, including 6 novel ones, were discovered and structurally described under the present conditions. Oxidation, demethylation, dehydrogenation, O‐dealkylation and glutathione (GSH) conjugation were all involved in the metabolism of pyrotinib in hepatocytes. The most predominant metabolic route was identified as GSH conjugation (M5). Conclusions: This study generated valuable metabolite profiles of pyrotinib in several species, which will aid in the understanding of the drug's disposition in various species and in evaluating the contribution of metabolites to overall effectiveness and toxicity of pyrotinib. [ABSTRACT FROM AUTHOR]