Towards better understanding SCRAs and metabolites in recreational drug intoxications associated with 5F-MDMB-PICA use

Abstract

Synthetic cannabinoid receptor agonists (SCRAs) pose a danger to public health. Historically, SCRA use has been associated with a multitude of adverse events, including neurotoxicity and cardiotoxicity. Numerous case reports are published on observed SCRA toxicity, however clear studies on the toxicity of SCRAs in humans are lacking because of obvious ethical reasons. This study focused on a unique cohort of patients experiencing recreational drug toxicity, who had used 5F-MDMB-PICA, to better understand the effects of SCRAs and their metabolites in humans. All patients were evaluated regarding vital signs, Glasgow Coma Scale (GCS) and clinical features. Liquid chromatography coupled to high resolution mass spectrometry (LC-HRMS) confirmed and quantified the presence of 5F-MDMB-PICA (and/or metabolites) as the only SCRA present in the serum of 71 patients (Janssens et al., Clinical Chemistry , 2022, in press, https://doi.org/10.1093/clinchem/hvac027 ). Cannabinoid activity was assessed in extracts from all serum samples by a cannabinoid receptor (CB1) bioassay, allowing to assess the relationship between serum concentrations and ex vivo human CB1 activation potential. Furthermore, a link with the clinical presentation was appraised. 5F-MDMB-PICA and metabolites were pharmacologically profiled in vitro to evaluate the theoretically possible contribution of active metabolites to overall cannabinoid activity. This revealed the presence of active in vivo metabolites M2 (oxidative defluorination) and M7 (ester hydrolysis) in serum. Serum levels of 5F-MDMB-PICA were correlated to the ex vivo cannabinoid activity, revealing a sigmoidal relationship. The latter could also be predicted based on the pharmacological characterization and an in-depth investigation of the bioassay outcome. Regarding the clinical presentation, the GCS showed a significant trend (decrease) upon increasing ex vivo cannabinoid activity. Trends for the occurrence of symptoms or an altered heart rate, blood pressure or body temperature were non-significant. Although high concentrations of 5F-MDMB-PICA metabolites (M2 and M7) were present in serum, a negligible contribution of these active metabolites to the overall cannabinoid activity in serum was anticipated, based on their in vitro CB1 receptor activation potential. Prediction of ex vivo cannabinoid activity was made possible by generating a mathematical formula based on the pharmacological characterization of reference standards of all compounds that were detected in serum. Including correction factors within this formula to account for incomplete recovery and matrix effects within the bioassay was necessary as – in contrast to the analytical method – no internal standard could be used due to retained CB1 activation potential of SCRA internal standards. The clinical presentation of 5F-MDMB-PICA-intoxicated patients was not unequivocally correlated to the ex vivo cannabinoid activity in their serum. On the one hand, the level of consciousness significantly correlated to the ex vivo cannabinoid activity that could be measured within extracts of their serum. This is in line with previous reports of SCRA misuse resulting in drowsiness or ‘zombie-like’ effects. The insignificance of other clinical trends, on the other hand, suggest that the clinical presentation regarding SCRA abuse cannot be deemed as clear-cut. This is the first study to evaluate in a large patient cohort the correlation between possible toxic effects of 5F-MDMB-PICA misuse and ex vivo cannabinoid activity. Pharmacological profiling and in-depth bioassay analysis allowed a better understanding of the contribution of 5F-MDMB-PICA and active metabolites to the total CB1 activity present in serum, suggesting a negligible contribution by metabolites of this specific SCRA despite the high concentrations in serum.