Since the 2000s, more new psychoactive substances have appeared on the illicit drug market. β-Keto-arylcyclohexylamine compounds, which have pharmacological roles in anesthesia, are increasingly used recreationally, but detailed toxicity data are lacking. Analyzing their metabolites can help forensic personnel determine whether someone has taken these illicit substances. This study examined the in vitro and in vivo metabolism of three such compounds: deschloro-N-ethyl-ketamine, fluoro-N-ethyl-ketamine, and bromoketamine. Using zebrafish and human liver microsomes, 49 metabolites were identified via liquid chromatography-high-resolution mass spectrometry. Hydroxy-deschloro-N-ethyl-ketamine, hydroxy-fluoro-N-ethyl-ketamine, and hydroxy-bromoketamine are recommended as biomarkers for documenting intake in clinical and forensic cases.
Proscaline and methallylescaline are two phenylethylamine derivatives of the classic hallucinogen mescaline, classified as new psychoactive substances (NPS) not controlled by international drug conventions. Limited toxicity information has hindered their identification. Using high-resolution mass spectrometry with three complementary models—computational prediction, zebrafish (in vivo), and human liver microsomes (in vitro)—the study identified 7 proscaline metabolites and 11 methallylescaline metabolites for the first time. Hydroxylated and N-acetylated products were the major metabolites, enabling their selection as biomarkers for detecting intake of these two NPS over a relatively wide detection window.