Metabolic fate, mass spectral fragmentation, detectability, and differentiation in urine of the benzofuran designer drugs 6-APB and 6-MAPB in comparison to their 5-isomers using GC-MS and LC-(HR)-MSn techniques

The number of so-called new psychoactive substances (NPS) is still increasing by modification of the chemical structure of known (scheduled) drugs. As analogues of amphetamines, 2-aminopropyl-benzofurans were sold. They were consumed because of their euphoric and empathogenic effects. After the 5-(2-aminopropyl)benzofurans, the 6-(2-aminopropyl)benzofuran isomers appeared. Thus, the question arose whether the metabolic fate, the mass spectral fragmentation, and the detectability in urine are comparable or different and how an intake can be differentiated. In the present study, 6-(2-aminopropyl)benzofuran (6-APB) and its N-methyl derivative 6-MAPB (N-methyl-6-(2-aminopropyl)benzofuran) were investigated to answer these questions. The metabolites of both drugs were identified in rat urine and human liver preparations using GC-MS and/or liquid chromatography-high resolution-mass spectrometry (LC-HR-MSn). Besides the parent drug, the main metabolite of 6-APB was 4-carboxymethyl-3-hydroxy amphetamine and the main metabolites of 6-MAPB were 6-APB (N-demethyl metabolite) and 4-carboxymethyl-3-hydroxy methamphetamine. The cytochrome P450 (CYP) isoenzymes involved in the 6-MAPB N-demethylation were CYP1A2, CYP2D6, and CYP3A4. An intake of a common users’ dose of 6-APB or 6-MAPB could be confirmed in rat urine using the authors’ GC-MS and the LC-MSn standard urine screening approaches with the corresponding parent drugs as major target allowing their differentiation. Furthermore, a differentiation of 6-APB and 6-MAPB in urine from their positional isomers 5-APB and 5-MAPB was successfully performed after solid phase extraction and heptafluorobutyrylation by GC-MS via their retention times

Metabolic fate of desomorphine elucidated using rat urine, pooled human liver preparations, and human hepatocyte cultures as well as its detectability using standard urine screening approaches.

Desomorphine is an opioid misused as "crocodile", a cheaper alternative to heroin. It is a crude synthesis product homemade from codeine with toxic byproducts. The aim of the present work was to investigate the metabolic fate of desomorphine in vivo using rat urine and in vitro using pooled human liver microsomes and cytosol as well as human liver cell lines (HepG2 and HepaRG) by Orbitrap-based liquid chromatography-high resolution-tandem mass spectrometry or hydrophilic interaction liquid chromatography. According to the identified metabolites, the following metabolic steps could be proposed: N-demethylation, hydroxylation at various positions, N-oxidation, glucuronidation, and sulfation. The cytochrome P450 (CYP) initial activity screening revealed CYP3A4 to be the only CYP involved in all phase I steps. UDP-glucuronyltransferase (UGT) initial activity screening showed that UGT1A1, UGT1A8, UGT1A9, UGT1A10, UGT2B4, UGT2B7, UGT2B15, and UGT2B17 formed desomorphine glucuronide. Among the tested in vitro models, HepaRG cells were identified to be the most suitable tool for prediction of human hepatic phase I and II metabolism of drugs of abuse. Finally, desomorphine (crocodile) consumption should be detectable by all standard urine screening approaches mainly via the parent compound and/or its glucuronide assuming similar kinetics in rats and humans