Metabolite markers for three synthetic tryptamines N-ethyl-N-propyltryptamine, 4-hydroxy-N-ethyl-N-propyltryptamine, and 5-methoxy-N-ethyl-N-propyltryptamine

Marianne Skov-Skov Bergh; Inger Lise Bogen; Katharina Elisabeth Grafinger; Marilyn A Huestis; Åse Marit Leere Øiestad

doi:10.1002/dta.3668

Metabolite markers for three synthetic tryptamines N-ethyl-N-propyltryptamine, 4-hydroxy-N-ethyl-N-propyltryptamine, and 5-methoxy-N-ethyl-N-propyltryptamine

Drug Test Anal. 2024 Mar 9. doi: 10.1002/dta.3668. Online ahead of print.

Authors

Marianne Skov-Skov Bergh¹, Inger Lise Bogen^{1

2}, Katharina Elisabeth Grafinger³, Marilyn A Huestis⁴, Åse Marit Leere Øiestad⁵

Affiliations

¹ Section for Drug Abuse Research, Department of Forensic Sciences, Division of Laboratory Medicine, Oslo University Hospital, Oslo, Norway.
² Section for Pharmacology and Pharmaceutical Biosciences, Department of Pharmacy, The Faculty of Mathematics and Natural Sciences, University of Oslo, Oslo, Norway.
³ Institute of Chemistry and Bioanalytics, University of Applied Sciences and Arts Northwestern Switzerland, Muttenz, Switzerland.
⁴ Institute of Emerging Health Professions, Thomas Jefferson University, Philadelphia, Pennsylvania, USA.
⁵ Section for Forensic Toxicological Analytics, Department of Forensic Sciences, Division of Laboratory Medicine, Oslo University Hospital, Oslo, Norway.

PMID: 38459837
DOI: 10.1002/dta.3668

Abstract

N-Ethyl-N-propyltryptamine (EPT), 4-hydroxy-N-ethyl-N-propyltryptamine (4-OH-EPT), and 5-methoxy-N-ethyl-N-propyltryptamine (5-MeO-EPT) are new psychoactive substances classified as tryptamines, sold online. Many tryptamines metabolize rapidly, and identifying the appropriate metabolites to reveal intake is essential. While the metabolism of 4-OH-EPT and 5-MeO-EPT are not previously described, EPT is known to form metabolites by indole ring hydroxylation among others. Based on general knowledge of metabolic patterns, 5-MeO-EPT is also expected to form ring hydroxylated EPT (5-OH-EPT). In the present study, the aim was to characterize the major metabolites of EPT, 4-OH-EPT, and 5-MeO-EPT, to provide markers for substance identification in forensic casework. The tryptamines were incubated with pooled human liver microsomes at 37°C for up to 4 h. The generated metabolites were separated and detected by ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry analysis. The major in vitro EPT metabolites were formed by hydroxylation, N-dealkylation, and carbonylation. In comparison, 4-OH-EPT metabolism was dominated by double bond formation, N-dealkylation, hydroxylation, and carbonylation in vitro and hydroxylation or carbonylation combined with double bond loss, carbonylation, N-dealkylation, and hydroxylation in vivo. 5-MeO-EPT was metabolized by O-demethylation, hydroxylation, and N-dealkylation in vitro. The usefulness of the characterized metabolites in forensic casework was demonstrated by identification of unique metabolites for 4-OH-EPT in a human postmortem blood sample with suspected EPT or 4-OH-EPT intoxication.

Keywords: 4-hydroxy-N-ethyl-N-propyltryptamine (4-OH-EPT); 5-methoxy-N-ethyl-N-propyltryptamine (5-MeO-EPT); N-ethyl-N-propyltryptamine (EPT); metabolite; microsomes; new psychoactive substances (NPS); synthetic tryptamines; ultra-high performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UHPLC-QTOF-MS).