Metabolomics reveals the formation of aldehydes and iminium in gefitinib metabolism

Identifying the reactive metabolites of tyrosine kinase inhibitors in a comprehensive approach: Implications for drug‐drug interactions and hepatotoxicity

“…During metabolism studies, aldehydes generated through morpholine ring oxidation have been identified using reference standards in rats and dogs, as well as in HLM, a finding consistent with the methoxylamine adducts reported by Kenny et al The latter also reported cyanide adducts in HLM incubations whose generation was later confirmed by Liu et al Using a metabolomic approach and LC‐MS analyses, they investigated the metabolic pathways of gefitinib 21 in mouse liver microsomes (MLM) and HLM. Among 34 metabolites and adducts (GSH, methoxylamine, and cyanide), two new aldehydes 90 and 91 and one iminium 92 RM were reported . Gefitinib N ‐dealkylation on the side chain, alone or in combination with oxidative defluorination, gave rise to these aldehydes whose generation was attested by the detection of the corresponding alcohols, carboxylic acids, and oximes.…”

“…Oxidative defluorination, though uncommon in drug metabolism, has been identified as a minor metabolism pathway in humans for gefitinib, famitinib, and sunitinib . For these drugs, GSH adducts were detected in liver microsomal incubations . As discussed above for dasatinib analogues, they have been suggested to result from p ‐quinone‐imine derivatives 18 , 22 and 25 generated via an oxidative defluorination pathway .…”

“…For these drugs, GSH adducts were detected in liver microsomal incubations . As discussed above for dasatinib analogues, they have been suggested to result from p ‐quinone‐imine derivatives 18 , 22 and 25 generated via an oxidative defluorination pathway . For gefitinib, these GSH adducts are indeed unlikely to arise from an o ‐quinone RM, since gefitinib catechol derivative has not been evidenced in vitro or in vivo though O ‐dealkylation is one of its main metabolic pathways .…”

A novel humanized mouse lacking murine P450 oxidoreductase for studying human drug metabolism

“…Gefitinib is metabolized primarily by the P450 cytochrome system, including CYP3A4 and 2D6. We recently identified new gefitinib metabolites and demonstrated considerable differences between human and mouse liver microsomes 39 , but regardless of dose, route, or species, gefitinib is excreted primarily in the feces (<7% in the urine) 40, 41 . We therefore analyzed the feces of non-humanized PIRF mice for gefitinib metabolites during the first 16 h after intravenous injection of gefitinib.…”

“…Mass chromatograms and mass spectra were acquired by MassHunter Workstation data Acquisition software (Agilent, Santa Clara, CA) in centroid and profile formats from m/z 50 to 1000. The acquisition rate was set as 1.5 spectra per s. The method used in this study has been validated by our previous study of gefitinib metabolism in human liver microsomes 39 . Meanwhile, the quality control samples were performed every 10 samples in the process of the sample running.…”