Pentylindole/Pentylindazole Synthetic Cannabinoids and Their 5-Fluoro Analogs Produce Different Primary Metabolites: Metabolite Profiling for AB-PINACA and 5F-AB-PINACA

Abstract

Abstract. Whereas non-fluoropentylindole/indazole synthetic cannabinoids appear to be metabolized preferably at the pentyl chain though without clear preference for one specific position, their 5-fluoro analogs' major metabolites usually are 5-hydroxypentyl and pentanoic acid metabolites. We determined metabolic stability and metabolites of N-(1-amino-3-methyl-1-oxobutan-2-yl)-1-pentyl-1H-indazole-3-carboxamide (AB-PINACA) and 5-fluoro-AB-PINACA (5F-AB-PINACA), two new synthetic cannabinoids, and investigated if results were similar. In silico prediction was performed with MetaSite (Molecular Discovery). For metabolic stability, 1 μmol/L of each compound was incubated with human liver microsomes for up to 1 h, and for metabolite profiling, 10 μmol/L was incubated with pooled human hepatocytes for up to 3 h. Also, authentic urine specimens from AB-PINACA cases were hydrolyzed and extracted. All samples were analyzed by liquid chromatography high-resolution mass spectrometry on a TripleTOF 5600+ (AB SCIEX) with gradient elution (0.1% formic acid in water and acetonitrile). High-resolution full-scan mass spectrometry (MS) and information-dependent acquisition MS/MS data were analyzed with MetabolitePilot (AB SCIEX) using different data processing algorithms. Both drugs had intermediate clearance. We identified 23 AB-PINACA metabolites, generated by carboxamide hydrolysis, hydroxylation, ketone formation, carboxylation, epoxide formation with subsequent hydrolysis, or reaction combinations. We identified 18 5F-AB-PINACA metabolites, generated by the same biotransformations and oxidative defluorination producing 5-hydroxypentyl and pentanoic acid metabolites shared with AB-PINACA. Authentic urine specimens documented presence of these metabolites. AB-PINACA and 5F-AB-PINACA produced suggested metabolite patterns. AB-PINACA was predominantly hydrolyzed to AB-PINACA carboxylic acid, carbonyl-AB-PINACA, and hydroxypentyl AB-PINACA, likely in 4-position. The most intense 5F-AB-PINACA metabolites were AB-PINACA pentanoic acid and 5-hydroxypentyl-AB-PINACA.

High-Resolution Mass Spectrometry for Characterizing the Metabolism of Synthetic Cannabinoid THJ-018 and Its 5-Fluoro Analog THJ-2201 after Incubation in Human Hepatocytes

“…This might be attributed to electron cloud distribution differences between indole and indazole rings. Likewise, no indazole-hydroxylated metabolites were observed for AKB-48 and AB-PINACA (19,34 ). Both AM-2201 and THJ-2201 underwent oxidative defluorination with subsequent carboxylation and glucuronidation (11,16 ).…”

“…Fragments m/z 229.0979 and 85.0644 indicated pentyl chain carbonylation. Intense m/z 273.1017 betrays 1Ј-carbonylation, in which case the amido bond cleaves easily (5,19,26 ). M13 was the most lipophilic metabolite, eluting at 16.55 min.…”

“…However, for THJ-2201, we detected F26 (5Ј-OH-THJ-018) and F18 (5Ј-OH-THJ-018 glucuronide) only after oxidative defluorination. Oxidative defluorination also was the primary metabolic pathway for fluorinated SC, such as AM-2201 (16 ), 5F-AB-PINACA (19 ), , and 5F-PB-22 (36 ), and it dominated THJ-2201 metabolism. F26 and F18 have retention times and spectra identical to those of M8 and M4, respectively.…”

“…Metabolites identified with human hepatocytes can serve as useful markers for identifying novel SCs (19 ). Recent increases in drug-related emergency visits have been linked to new novel psychoactive substances (NPSs) (20 ).…”

In Vitro and In Vivo Human Metabolism of Synthetic Cannabinoids FDU-PB-22 and FUB-PB-22

“…The hepatocyte incubation model was successful in our previous studies for identifying appropriate markers for AB-FUBINACA (19), AB-PINACA (22), and AH-7921 (23), among others. Two urine samples collected from individuals suspected of driving under the influence of drugs also were analyzed to assess utility of our in vitro conclusions.…”