Identification and Characterization of Dacomitinib Metabolites in Rats by Liquid Chromatography Combined With Q-Exactive-Orbitrap High Resolution Mass Spectrometry

Dacomitinib is an irreversible inhibitor targeting epidermal growth factor receptor, which has been developed for the treatment of metastatic non-small cell lung cancer (NSCLC). The aim of this study was to establish a reliable liquid chromatography combined with high resolution mass spectrometric method to identify and characterize the metabolites of dacomitinib in rats. In vitro metabolism was investigated through 60-min incubation with rat liver microsomes, while in vivo analysis involved bile and urine sample collection following a single oral 10 mg/kg dose. A total of 18 metabolites, were structurally elucidated through accurate MS measurements, MS² spectral interpretation, and fragmentation pattern analysis, including two GSH conjugates and two N-acetyl-cysteine conjugates. Among these metabolites, a total of 12 metabolites were first reported, i.e., M1, M2, M3, M7, M9, M10, M11, M13, M14, M15, M16, and M17. The parent drug remained the predominant species across all metrices. The primary metabolic pathways included: oxidative defluorination, O-demethylation, N-dealkylation, oxidative deamination, piperidin ring opening, N-oxygenation, lactam formation, dehydrogenation, and hydroxylation. Phase II biotransformation pathways included GSH conjugation and N-acetyl-cysteine conjugation. These findings enhance understanding of dacomitinib's metabolic fate, providing critical insights into its elimination mechanisms, and supporting subsequent evaluation of therapeutic efficacy and safety profiles.