Study of the Metabolic Profiles of “Indazole-3-Carboxamide” and “Isatin Acyl Hydrazone” (OXIZID) Synthetic Cannabinoids in a Human Liver Microsome Model Using UHPLC-QE Orbitrap MS

Abstract

Unregulated core structures, “isatin acyl hydrazones” (OXIZIDs), have quietly appeared on the market since China legislated to ban seven general core scaffolds of synthetic cannabinoids (SCs). The fast evolution of SCs presents clinical and forensic toxicologists with challenges. Due to extensive metabolism, the parent compounds are barely detectable in urine. Therefore, studies on the metabolism of SCs are essential to facilitate their detection in biological matrices. The aim of the present study was to elucidate the metabolism of two cores, “indazole-3-carboxamide” (e.g., ADB-BUTINACA) and “isatin acyl hydrazone” (e.g., BZO-HEXOXIZID). The in vitro phase I and phase II metabolism of these six SCs was investigated by incubating 10 mg/mL pooled human liver microsomes with co-substrates for 3 h at 37 °C, and then analyzing the reaction mixture using ultrahigh-performance liquid chromatography-quadrupole/electrostatic field orbitrap mass spectrometry. In total, 9 to 34 metabolites were detected for each SC, and the major biotransformations were hydroxylation, dihydrodiol formation (MDMB-4en-PINACA and BZO-4en-POXIZID), oxidative defluorination (5-fluoro BZO-POXIZID), hydrogenation, hydrolysis, dehydrogenation, oxidate transformation to ketone and carboxylate, N-dealkylation, and glucuronidation. Comparing our results with previous studies, the parent drugs and SC metabolites formed via hydrogenation, carboxylation, ketone formation, and oxidative defluorination were identified as suitable biomarkers.

Fatal Overdose with the Cannabinoid Receptor Agonists MDMB-4en-PINACA and 4F-ABUTINACA: A Case Report and Review of the Literature

“…According to their findings, the major metabolic pathways involved in MDMB-4en-PINACA metabolism are ester hydrolysis and hydroxylation, and up to nine metabolites can be detected in the serum [ 27 ]. Xiang et al also identified further ketone metabolites and special phase II metabolites [ 28 ]. Various clinical symptoms were reported after using MDMB-4en-PINACA, such as headaches, seizures, paranoia, anxiety, hallucinations, amnesia, mydriasis, nausea, and vomiting [ 29 , 30 ].…”

“…According to their findings, the major metabolic pathways involved in MDMB-4en-PINACA metabolism are ester hydrolysis and hydroxylation, and up to nine metabolites can be detected in the serum [27]. Xiang et al also identified further ketone metabolites and special phase II metabolites [28]. 4F-ABUTINACA-also known as N-(4-fluorobutyl)-APINACA or 4F-ABINACA, with the IUPAC name N-(1-adamantyl)-1-(4-fluorobutyl)indazole-3-carboxamide-is a fourth generation indazole-adamantyl-derived SCRA (Figure 1).…”