LAUSR

HighlightsThe in vitro metabolites of FAK inhibitors were analyzed by LC/MS/MS.The structures and fragmentation patterns were characterized.Typical metabolic pathways include hydroxylation, dehydrogenation and N‐dealkylation. ABSTRACT Focal adhesion kinase (FAK), a non‐receptor tyrosine kinase, is critically involved in cell migration, spreading and proliferation at the early step of various cancers. Small molecule inhibitors of FAK are effective to inhibit its activation in the process of tumor formation in cell. To better understand biotransformation of FAK inhibitors, this work has investigated in vitro phase I metabolism of inhibitors (namely PF‐573228, PF‐562271 and PF‐03814735) by rat liver microsomes model. Using liquid chromatography ‐ quadrupole time of flight mass spectrometry and tandem mass spectrometry (LC/Q‐TOF/MS and MS/MS), three metabolites of PF‐573228 and PF‐562271 were observed and characterized, respectively. These in vitro metabolites were reported for the first time. The structures and fragmentation patterns of these metabolites were elucidated, and phase I metabolic pathways for FAK inhibitors were proposed. The main metabolic pathways of PF‐573228 were hydroxylation, dehydrogenation and N‐dealkylation. For PF‐562271, they were hydroxylation and dehydrogenation. Hydroxylation was observed as the primary metabolism for PF‐0381473.