Synthetic cannabinoid BB-22 (QUCHIC): Human hepatocytes metabolism with liquid chromatography-high resolution mass spectrometry detection

Clandestine laboratories continue producing new synthetic cannabinoids that mimic and magnify natural cannabinoids effects to circumvent drug scheduling legislation. New synthetic cannabinoids are highly potent and responsible for many acute intoxications and deaths. Characterization of metabolic pathways is critical to identify metabolite markers whose detection can prove intake. BB-22 is a new potent synthetic cannabinoid whose toxicological and metabolic properties are currently unavailable. Analytical methods require constant updating and are challenging due to extensive synthetic cannabinoid metabolism and low marker concentrations. A single non-specific BB-22 metabolite was previously identified in incubations with human liver microsomes (BB-22 3-carboxyindole). Clear characterization of BB-22’s metabolism is required to help toxicologists document BB-22 consumption in clinical and forensic cases. We incubated 10 μmol/L BB-22 with cryopreserved human hepatocytes for 3 h. Samples were analyzed by liquid chromatography on a biphenyl column and high resolution mass spectrometry. Results were processed with data mining software, identifying ten metabolites. Loss of the quinolinyl side-chain via ester hydrolysis was the main biotransformation. All other metabolites were produced by further indole or cyclohexylmethyl hydroxylation or glucuronidation. We recommend BB-22 3-carboxyindole and two BB-22 3-carboxyindole-hydroxycyclohexylmethyl isomers as metabolite targets for documenting BB-22 intake. Hydrolysis of biological samples before analysis is strongly suggested to improve detection of phase I metabolites. BB-22 3-carboxyindole is not specific for BB-22 intake, as it was previously detected as a minor MDMB-CHMICA and ADB-CHMICA metabolite. Consumption of these two synthetic cannabinoids should be ruled out to confirm BB-22 intake.