Distinguishing Intake of New Synthetic Cannabinoids ADB-PINACA and 5F-ADB-PINACA with Human Hepatocyte Metabolites and High-Resolution Mass Spectrometry.

ADB-PINACA and its 5-fluoropentyl analog 5F-ADB-PINACA are among the most potent synthetic cannabinoids tested to date, with several severe intoxication cases. ADB-PINACA and 5F-ADB-PINACA have a different legal status, depending on the country. Synthetic cannabinoid metabolites predominate in urine, making detection of specific metabolites the most reliable way for proving intake in clinical and forensic specimens. However, there are currently no data on ADB-PINACA and 5F-PINACA metabolism. The substitution of a single fluorine atom distinguishes the 2 molecules, which may share common major metabolites. For some legal applications, distinguishing between ADB-PINACA and 5F-PINACA intake is critical. For this reason, we determined the human metabolic fate of the 2 analogs.

ADB-PINACA and 5F-PINACA were incubated for 3 h with pooled cryopreserved human hepatocytes, followed by liquid chromatography-high-resolution mass spectrometry analysis. Data were processed with Compound Discoverer.

We identified 19 and 12 major ADB-PINACA and 5F-ADB-PINACA metabolites, respectively. Major metabolic reactions included pentyl hydroxylation, hydroxylation followed by oxidation (ketone formation), and glucuronidation of ADB-PINACA, and oxidative defluorination followed by carboxylation of 5F-ADB-PINACA.

We recommend ADB-PINACA ketopentyl and hydroxypentyl, and ADB-PINACA 5-hydroxypentyl and pentanoic acid, as optimal markers for ADB-PINACA and 5F-ADB-PINACA intake, respectively. Since the 2 compounds present positional isomers as the primary metabolites, monitoring unique product ions and optimized chromatographic conditions are required for a clear distinction between ADB-PINACA and 5F-ADB-PINACA intake.