Identification and quantification of predominant metabolites of synthetic cannabinoid MAB-CHMINACA in an authentic human urine specimen.

An autopsy case in which the cause of death was judged as drug poisoning by two synthetic cannabinoids, including MAB-CHMINACA, was investigated. Although unchanged MAB-CHMINACA could be detected from solid tissues, blood and stomach contents in the case, the compound could not be detected from a urine specimen. We obtained six kinds of reference standards of MAB-CHMINACA metabolites from a commercial source. The MAB-CHMINACA metabolites from the urine specimen of the abuser were extracted using a QuEChERS method including dispersive solid-phase extraction, and analyzed by liquid chromatography-tandem mass spectrometry with or without hydrolysis with β-glucuronidase. Among the six MAB-CHMINACA metabolites tested, two predominant metabolites could be identified and quantified in the urine specimen of the deceased. After hydrolysis with β-glucuronidase, an increase of the two metabolites was not observed. The metabolites detected were a 4-monohydroxycyclohexylmethyl metabolite M1 (N-(1-amino-3,3-dimethyl-1-oxobutan-2-yl)-1-((4-hydroxycyclohexyl)methyl)-1H-indazole-3-carboxamide) and a dihydroxyl (4-hydroxycyclohexylmethyl and tert-butylhydroxyl) metabolite M11 (N-(1-amino-4-hydroxy-3,3-dimethyl-1-oxobutan-2-yl)-1-((4-hydroxycyclohexyl)methyl)-1H-indazole-3-carboxamide). Their concentrations were 2.17 ± 0.15 and 10.2 ± 0.3 ng/mL (n = 3, each) for M1 and M11, respectively. Although there is one previous in vitro study showing the estimation of metabolism of MAB-CHMINACA using human hepatocytes, this is the first report dealing with in vivo identification and quantification of MAB-CHMINACA metabolites in an authentic human urine specimen.