Although there were reports on the metabolism of 4F-MDMB-BINACA using in-vivo and various in-vitro models, studies were either conducted using small in-vivo sample size such as 1 to 4 samples [5, 29] or in closed environments such as forensic psychiatric wards and prisons . The hepatic cell line HepG2 is often used as an initial screen as it is known to produce high reproducibility results with relatively stable enzyme concentration, although they are limited by the low-level expression of several metabolizing enzymes, including the cytochrome P450 (CYP) class of proteins [17, 18]. In-vitro metabolism studies are generally used to complement these data using perfused organs, tissue or cell cultures and microsomal preparations amongst which pooled human liver microsomes (HLM) have been frequently used to elucidate metabolism of SCBs [12,13,14,15,16]. Since most SCBs are found extensively in metabolized forms in urine, the identification of metabolites is of vital importance for forensic and clinical toxicologists. Identifying SCB intake and its correlating specific adverse effects require rapid elucidation of these SCBs. The proliferation of SCBs has become a global challenge as new compounds are rapidly introduced into the illegal drug market to evade existing drug law


Tremors were observed in mice 30 minutes following 1 mg/kg AMB-FUBINACA in the present study. Pretreatment times and dose ranges for the drug discrimination assay were selected based on the time of peak depression in the locomotor activity assay in mice. Average potency of the discriminative stimulus effects of early compounds was 0.81±0.17 mg/kg (Gatch et al., 2014), whereas the potency of a recent set was 0.09±0.03 mg/kg (Gatch et al., 2018), and the potency of the current set is 0.05±0.01 mg/kg. Short-onset, short-acting compounds have a greater abuse liability, and long-acting compounds pose problems of long-acting adverse effects and interactions with other drugs. The duration of action of the synthetic cannabinoids tested using the 8-h protocol have varied widely, with some producing a duration of action no longer than 1 h, others producing a duration of action between 1–2 h, and others lasting more than 2 h. There seems to be a trend of newer synthetic cannabinoids being more potent than earlier compound

One recent study has looked at other mechanisms of action in some of the older synthetic cannabinoids and reported that some produced varying amounts of activity at sites which are related to cardiotoxicity and heart disease (Wiley et al., 2016


Due to the unknown toxicity of newly emerging SCRAs, forensic assessments of cases involving these substances are challenging. According to the reported cases and reviews of the scientific literature, concurrent ethanol consumption should amplify the toxicity of SCRAs. The concentration of 4F-MDMB-BINACA in the postmortem blood was 2.50 and 2.34 ng/mL, and blood alcohol concentration was 2.11 and 2.49 g/L, respectively. Two fatal cases are reported caused by simultaneous consumption of 4F-MDMB-BINACA and ethanol.
Fig. 2.
4F-MDMB-BINACA was hydrolysed via ester hydrolysis forming the 4F-MDMB-BINACA ester hydrolysis metabolite (B22). Data obtained from the twenty urine samples were retrospectively analysed and processed using TraceFinder software based on the identification criteria of mass errors less than ± 5 ppm for full MS peaks and MS/MS peaks from the theoretical mass and matching of MS/MS spectra. The mixture was vortex-mixed and 500 µL of this mixture and 500 µL of methanol were loaded onto the Clean Screen FASt® tube. After incubation, the mixture was cooled at room temperature, and 150 µL of purified water was added. High-resolution QTOF-MS data were acquired on an Agilent 6510 Accurate Mass QTOF mass spectrometer (Agilent Technologies) equipped with dual electrospray ionization (ESI) source operated in both positive and negative ion modes, to determine accurate masses of the metabolites. Chromatographic separation was performed on an Agilent 1290 LC system with a Poroshell 120 EC-C18 analytical column (2.7 μm, 75 × 2.1 mm; Agilent Technologies, Santa Clara, CA, USA).
Fig. 1.
Monitoring metabolism of synthetic cannabinoid 4F-MDMB-BINACA via high-resolution mass spectrometry assessed in cultured hepatoma cell line, fungus, 5CL ADBA powder liver microsomes and confirmed using urine samples The threshold for fatal overdose of combined use of SCRAs and ethanol can be estimated as a little ng/mL (0.37–4.1 ng/mL according to the reported cases) of SCRA and 1.5–2.5 g/L of ethanol. The reported cases and reviews of the scientific literature suggest a possible synergistic effect between SCRAs and ethanol, because their combined use clearly increases their toxicity. The victim died due to severe necrotizing pancreatitis and acute kidney injury evolving into multi-organ failure 11 days after hospital admission . Studies have found no unequivocal synergistic effect between THC and ethanol at low or moderate ethanol doses [29, 30], but no data on high doses of ethanol are available. Given that THC and ethanol act on the same receptors, data on their simultaneous use may yield important insights in this regard.
Fungus C. elegans
Concentrations of 4F-MDMB-BINACA in the postmortem blood samples were 2.50 and 2.34 ng/mL, which are in line with published data. Although the lethal dose of 4F-MDMB-BINACA is unknown, its concentration in postmortem blood samples was found to range between 0.10 and 2.90 ng/mL . In SCRA-related cases in which the deceased suffered from heart disease, the SCRA concentration in the postmortem blood was less than 1 ng/mL . Concentrations of SCRAs in postmortem cases cover a wide range ; however, some reports of survival have also been published—even at relatively high blood SCRA concentrations [19, 20