In vitro and in vivo human metabolism of a synthetic cannabinoid EAM-2201 detected by LC–quadrupole-ion trap-MS/MS and high-resolution LC–Orbitrap-MS/MS

Purpose The aim of this study is to characterize the metabolites of EAM-2201 in human hepatocytes obtained in vitro and those in liver and urine specimens obtained in vivo from the autopsy of an EAM-2201 abuser. Methods EAM-2201 was incubated with human hepatocytes for 3 h in a CO 2 incubator and the metabolites of EAM-2201 were produced. The human liver specimen was homogenized and the metabolites were extracted. The urine specimen was hydrolyzed first with β-glucuronidase and the metabolites were extracted. The tentative detection and identification of those metabolites were performed using liquid chromatography (LC)–quadrupole-ion trap tandem mass spectrometry (MS/MS) and high-resolution LC–Orbitrap-MS/MS, respectively. Results Twelve metabolites of EAM-2201 could be characterized in hepatocytes, liver and urine. They were produced by defluorination, hydroxylation, carboxylation, dehydrogenation, N -dealkylation and/or glucuronidation of EAM-2201. The most detectable metabolite obtained from the in vitro hepatocyte incubation was that monohydroxylated at the 4-ethylnaphthalene moiety of EAM-2201 after dehydrogenation. However, only a trace amount of the same metabolite was detected in the liver tissue obtained postmortem from an EAM-2201 abuser. In the liver tissue, the highest metabolite was 5-carboxypentyl derivative of EAM-2201, which was monohydroxylated at the 4-ethylnaphthalene moiety, followed by monohydroxylpentyl and monohydroxy-4-ethylnaphthalenyl derivative of EAM-2201 without dehydrogenation. Conclusions Twelve metabolites of a synthetic cannabinoid, EAM-2201, were tentatively identified in human hepatocytes in vitro, and in human liver and urine specimens in vivo for the first time. There was a distinct difference in metabolism profile between the in vitro and in vivo results.