Despite the increasing relevance of synthetic cannabinoids as one of the most important classes within "New Psychoactive Substances", there is still a lack of knowledge concerning their metabolism in humans. Due to the extensive metabolism of synthetic cannabinoids, metabolites are necessarily the best target analytes in urine, posing additional challenges to forensic analysis. The aims of this study were to identify appropriate urinary targets indicating intake of THJ-018 or THJ-2201 as well as to elucidate the most important cytochrome P450 isoenzymes within the metabolism of THJ-018 and THJ-2201 in vitro. For this purpose, the in vitro metabolism of THJ-018 and THJ-2201 was initially established using pooled human liver microsomes. The results obtained were compared to previously published in vitro results as well as to the results of the metabolic profiles from selected recombinant cytochrome P450 isoenzymes and from 23 urine samples from forensic cases. LC-HRMS was used to conduct product ion scans and to examine the metabolite spectra. For THJ-018, 17 different metabolite groups containing 33 different metabolites and isomers were detected after microsomal incubation, with the major metabolic pathways being monohydroxylation at the pentyl chain and of the naphthyl moiety as well as dihydroxylation of both residues. For THJ-2201, 19 different metabolite groups and 46 different metabolites and isomers were observed. The major metabolic pathways were monohydroxylation at the naphthyl moiety and oxidative defluorination. Significant contribution to the in vitro metabolism of THJ-018 and THJ-2201 originated from CYP2B6, CYP2C19, CYP3A4, and CYP3A5. As several cytochrome P450 isoenzymes are involved in the metabolism of these synthetic cannabinoids, a co-consumption with other drugs is unlikely to have an impact on their metabolism.
Keywords: CYP isoforms; Phase I metabolism; Synthetic cannabinoids; THJ-018; THJ-2201; Urine.