Postmortem analysis of three methoxyacetylfentanyl-related deaths in Denmark and in vitro metabolite profiling in pooled human hepatocytes

The measured methoxyacetylfentanyl concentration was 0.022-0.056 mg/kg (N = 3) in femoral blood, 0.12 mg/kg (N = 1) in urine, and 0.074 mg/kg (N = 1) in brain tissue homogenate. A total of 10 metabolites were identified. The observed metabolic pathways were: hydroxylation(s), N-dealkylation, O-demethylation, deamination, glucuronidation, and combinations thereof. Major analytical targets in vitro and across measured biological samples in vivo were methoxyacetylfentanyl, the O-demethyl- metabolite, and the deamide-metabolite. Intoxication with methoxyacetylfentanyl was judged as the cause of death or a major contributing factor in all three presented cases.