Shape matters: The application of activity‐based in vitro bioassays and chiral profiling to the pharmacological evaluation of synthetic cannabinoid receptor agonists in drug‐infused papers seized in prisons

Abstract

Synthetic cannabinoid receptor agonists (SCRAs) elicit many of their psychoactive effects via type‐1 human cannabinoid (CB1) receptors. Enantiomer pairs of eight tert‐leucinate or valinate indole‐ and indazole‐3‐carboxamide SCRAs were synthesized and their CB1 potency and efficacy assessed using an in vitro β‐arrestin recruitment assay in a HEK239T stable cell system. A chiral high‐performance liquid chromatography method with photodiode array and/or quadrupole time‐of‐flight‐mass spectrometry detection (HPLC‐PDA and HPLC‐PDA‐QToF‐MS) was applied to 177 SCRA‐infused paper samples seized in Scottish prisons between 2018 and 2020. In most samples, SCRAs were almost enantiopure (S)‐enantiomer (>98% of total chromatographic peak area), although in some (n = 18), 2% to 16% of the (R)‐enantiomer was detected. (S)‐enantiomers are consistently more potent than (R)‐enantiomers and often more efficacious. The importance of SCRA‐CB1 receptor interactions in the “head” or “linked group” moiety is demonstrated, with the conformation of the “bulky” tert‐leucinate group greatly affecting potency (by up to a factor of 374), significantly greater than the difference observed between valinate SCRA enantiomers. (S)‐MDMB‐4en‐PINACA, (S)‐4F‐MDMB‐BINACA, and (S)‐5F‐MDMB‐PICA are currently the most prevalent SCRAs in Scottish prisons, and all have similar high potency (EC50, 1–5 nM) and efficacy. Infused paper samples were compared using estimated intrinsic efficacy at the CB1 receptor (EIECB1) to evaluate samples with variable SCRA content. Given their similar potency and efficacy, any variation in CB1 receptor‐mediated psychoactive effects are likely to derive from variation in dose, mode of use, pharmacokinetic differences, and individual factors affecting the user, rather than differences in the specific SCRA present.

A transnational perspective on the evolution of the synthetic cannabinoid receptor agonists market: Comparing prison and general populations

“…The qualitative and quantitative screening methods used have been described previously 21,22 and involve qualitative analysis by gas‐chromatography‐mass spectrometry (GC‐MS) and orthogonal confirmation by ultra‐performance liquid chromatography with photodiode array and quadrupole time of flight mass spectrometry (UPLC‐PDA‐QTOF‐MS). Selected results for samples seized between June 2018 and February 2020 have been reported previously 21–23 . Additional data from samples seized between October 2019 and September 2020 are presented herein for the first time.…”

“…While the emergence of prevalent SCRAs is very similar across all jurisdictions, being influenced by legislation in producer countries and international controls, national legislation can also drive increased diversity in local markets as well as international markets. There is relatively little diversity in the SCRA market in prisons in the United Kingdom with a limited number of compounds being detected at any given time, all with similarly high potency and efficacy, where pharmacological information is available 23,57 . Since the current UK legislation covers the most prevalent SCRAs on the market under analog controls (MDA 1971) and all other SCRAs that may not be covered under the PSA 2016, the United Kingdom may no longer be a driver of market diversification at a local or international level.…”

“…There is relatively little diversity in the SCRA market in prisons in the United Kingdom with a limited number of compounds being detected at any given time, all with similarly high potency and efficacy, where pharmacological information is available. 23,57 Since the current UK legislation covers the most prevalent SCRAs on the market under analog controls (MDA 1971) and all other SCRAs that may not be covered under the PSA 2016, the United Kingdom may no longer be a driver of market diversification at a local or international level. In contrast, the analog controls in Germany (NpSG) and the United States (CSA) appear to have led to increased diversity in the local market that does not appear to be reflected in other jurisdictions (i.e., γ-carbolinone SCRAs are rarely seen in the United Kingdom and United States).…”

Large‐scale evaluation of ion mobility spectrometry for the rapid detection of synthetic cannabinoid receptor agonists in infused papers in prisons

“…Cumyl‐4CN‐BINACA ( 5 ), 5F‐Cumyl‐PEGACLONE ( 7 ), ( S )‐ADB‐FUBINACA ( 8 ), PB‐22 (QUPIC) ( 9 ), FUB‐PB‐22 ( 10 ), ( S )‐5F‐ADB‐PINACA ( 11 ), ( S )‐5F‐AMB‐PINACA (5F‐AMB) ( 12 ), and ( S )‐ADB‐CHMINACA (MAB‐CHMINACA) ( 13 ) reference standards were obtained from Chiron, Trondheim, Norway, as 1mg ml −1 solutions in methanol. Reference standards for ( S )‐5F‐MDMB‐PICA ( 1 ) (>98.7% purity); ( S )‐4F‐MDMB‐BINACA ( 2 ) (99.7% purity); ( S )‐MDMB‐4en‐PINACA (5‐cl‐adb‐a) ( 3 ) (98.6% purity); ( S )‐5F‐MDMB‐PINACA ( 4 ) (99.6% purity); ( S )‐AMB‐CHMICA (MMB‐CHMICA) ( 6 ) (99.6% purity); ( S )‐AB‐CHMINACA ( 14 ) (>99% purity); ( S )‐AMB‐FUBINACA (MMB‐FUBINACA, FUB‐AMB) ( 15 ) (>98% purity); ( S )‐AMB‐4en‐PICA (MMB‐022, MMB‐4en‐PICA) ( 16 ) (99.7% purity); ( S )‐MDMB‐4en‐PICA ( 17 ) (>99.7% purity); ( S )‐MDMB‐FUBINACA ( 18 ) (>99.9% purity); and ( S )‐AB‐FUBINACA ( 19 ) (99% purity) were obtained via in‐house synthesis as detailed previously 5,39 . 5F‐PB‐22 (5F‐QUPIC) ( 20 ) (99% purity) and ( S )‐MDMB‐CHMICA ( 21 ) (99% purity) were synthesized and supplied by the Sutcliffe Group at Manchester Metropolitan University, Manchester, UK.…”

Overview of Synthetic Cannabinoids ADB-FUBINACA and AMB-FUBINACA: Clinical, Analytical, and Forensic Implications

“…AMB-FUBINACA has also the (S)-and (R)-configurations and the chiral centre at the C-2 carbon of the valinate side chain [29]. Chirality is common among SCs, implying different pharmacological and toxicological potencies among enantiomers [30][31][32][33][34]. As such, the assessment of the proportions of (S)-and (R)-enantiomers in the seized materials may allow for a better estimate of the risks users are exposed to.…”