Insights into the metabolism of CH-PIATA - a novel synthetic cannabinoid featuring an acetamide linker

Research output: Contribution to journalResearch articleContributedpeer-review


  • Annette Zschiesche - , University of Freiburg (First author)
  • Martin Scheu - , University of Freiburg (Author)
  • Detlef Thieme - , Institute of Doping Analysis and Sports Biochemistry Dresden (Author)
  • Annekathrin M Keiler - , Environmental Monitoring and Endocrinology (Research Group), Institute of Doping Analysis and Sports Biochemistry Dresden (Author)
  • Benedikt Pulver - , University of Freiburg (Author)
  • Laura M Huppertz - , University of Freiburg (Author)
  • Volker Auwärter - , University of Freiburg (Author)


The recent change from the popular carboxamide to an acetamide (ATA) linker scaffold in synthetic cannabinoid receptor agonists (SCRAs) can be interpreted as an attempt to circumvent legal regulations, setting new analytical challenges. Metabolites of N-cyclohexyl-2-(1-pentyl-1H-indol-3-yl)acetamide: CH-PIATA, the second ATA type SCRA detected in the EU, were investigated in urine and serum samples by LC-HRMS-MS and LC-MS-MS. Two different in vitro models: a pHLM assay and HepG2-cells as well as an in silico prediction by GLORYx freeware assisted in metabolite formation/identification. CH-PIATA was extensively metabolized, leading to metabolites formed primarily by mono- and dihydroxylation. For urine and serum specimens, monohydroxylation at the indole core or the methylene spacer of the acetamide linker (M1.8), carboxylic acid formation at the N-pentyl side chain (M3.1), and degradation of the latter leading to a tentatively identified N-propionic acid metabolite (M5.1) are suggested as reliable markers for substance intake. The N-propionic acid metabolite could not be confirmed in the in vitro assays as it includes multiple consecutive metabolic reactions. Furthermore, CH-PIATA could be detected as parent substance in blood samples, but not in urine. Both in vitro assays and the in silico tool proved suitable for predicting metabolites of CH-PIATA. Considering effort and costs, pHLM incubations seem to be more effective for metabolite prediction in forensic toxicology. The highlighted phase I metabolites serve as reliable urinary targets for confirming CH-PIATA use. The in silico approach is advantageous when reference material is unavailable.


Original languageEnglish
Article numberbkae013
Pages (from-to)359-371
Number of pages13
JournalJournal of analytical toxicology
Issue number5
Early online date5 Mar 2024
Publication statusPublished - May 2024

External IDs

ORCID /0000-0002-2157-4711/work/155292258
Mendeley c874eb45-057b-3b42-9369-5354e438413a
Scopus 85185490584


Sustainable Development Goals


  • Acetamides/metabolism, Cannabinoid Receptor Agonists/metabolism, Cannabinoids/metabolism, Chromatography, Liquid, Hep G2 Cells, Humans, Indoles/metabolism, Microsomes, Liver/metabolism, Substance Abuse Detection/methods, Tandem Mass Spectrometry