2019 Volume 42 Issue 4 Pages 623-630
The metabolism of butyrylfentanyl, a new designer drug, was investigated using fresh human hepatocytes isolated from a liver-humanized mouse model. In the culture medium of hepatocytes incubated with butyrylfentanyl, the desphenethylated metabolite (nor-butyrylfentanyl), ω-hydroxy-butyrylfentanyl, (ω-1)-hydroxy-butyrylfentanyl, 4′-hydroxy-butyrylfentanyl, β-hydroxy-butyrylfentanyl, 4′-hydroxy-3′-methoxy-butyrylfentanyl, and ω-carboxy-fentanyl were identified as the metabolites of butyrylfentanyl. Each metabolite was definitively identified by comparing the analytical data with those of authentic standards. The amount of the main metabolite, nor-butyrylfentanyl, reached 37% of the initial amount of butyrylfentanyl at 48 h. ω-Hydroxy-butyrylfentanyl and (ω-1)-hydroxy-butyrylfentanyl, formed by hydroxylation at the N-butyryl group of butyrylfentanyl, were the second and third largest metabolites, respectively. The majority of 4′-hydroxy-butyrylfentanyl and 4′-hydroxy-3′-methoxy-butyrylfentanyl was considered to be conjugated. CYP reaction phenotyping for butyrylfentanyl using human liver microsomes and various anti-CYP antibodies revealed that CYP3A4 was involved in the formation of nor-butyrylfentanyl, (ω-1)-hydroxy-butyrylfentanyl, and β-hydroxy-butyrylfentanyl. In contrast, CYP2D6 was involved in the formation of ω-hydroxy-butyrylfentanyl.
