title: Metabolites of 5F-AKB-48, a synthetic cannabinoid receptor agonist, identified in human urine and liver microsomal preparations using liquid chromatography high-resolution mass spectrometry.
abstract: New types of synthetic cannabinoid designer drugs are constantly introduced to the illicit drug market to circumvent legislation. Recently, N-​(1-Adamant​yl)-​1-​(5-​fluoropentyl)-​1H-​indazole-​3-​carboxamide (5F-AKB-48), also known as 5F-APINACA, was identified as an adulterant in herbal products. This compound deviates from earlier JHW-type synthetic cannabinoids by having an indazole ring connected to an adamantyl group via a carboxamide linkage. Synthetic cannabinoids are completely metabolized, and identification of the metabolites is thus crucial when using urine as the sample matrix. Using an authentic urine sample and high-resolution accurate-mass Fourier transform Orbitrap mass spectrometry, we identified 16 phase-I metabolites of 5F-AKB-48. The modifications included mono-, di-, and trihydroxylation on the adamantyl ring alone or in combination with hydroxylation on the N-fluoropentylindazole moiety, dealkylation of the N-fluoropentyl side chain, and oxidative loss of fluorine as well as combinations thereof. The results were compared to human liver microsomal (HLM) incubations, which predominantly showed time-dependent formation of mono-, di-, and trihydroxylated metabolites having the hydroxyl groups on the adamantyl ring. The results presented here may be used to select metabolites specific of 5F-AKB-48 for use in clinical and forensic screening.
authors.affiliation: Section of Forensic Chemistry, Department of Forensic Medicine, Faculty of Health and Medical Sciences, University of Copenhagen, Frederik V's Vej 11, 3, DK-2100, Denmark.
authors.forename: Niels Bjerre
authors.initials: NB
authors.lastname: Holm
authors.forename: Anders Just
authors.initials: AJ
authors.lastname: Pedersen
authors.forename: Petur Weihe
authors.initials: PW
authors.lastname: Dalsgaard
authors.forename: Kristian
authors.initials: K
authors.lastname: Linnet
mesh_terms: D000218:Adamantane / Q000031:analogs & derivatives* / Q000378:metabolism / Q000652:urine; D063386:Cannabinoid Receptor Agonists / Q000378:metabolism* / Q000652:urine*; D002853:Chromatography, Liquid / Q000379:methods; D015198:Designer Drugs / Q000032:analysis / Q000378:metabolism; D006801:Humans; D007191:Indazoles / Q000378:metabolism* / Q000652:urine*; D013058:Mass Spectrometry / Q000379:methods; D008862:Microsomes, Liver / Q000378:metabolism*
chemical_list: D063386:Cannabinoid Receptor Agonists; D015198:Designer Drugs; D007191:Indazoles; D000218:Adamantane; C000603150:N-(1-adamantyl)-1-(5-fluoropentyl)-1H-indazole-3-carboxamide
keywords: high-resolution mass spectrometry; human liver microsomes; metabolites; synthetic cannabinoids; urine