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


To evaluate whether the changes of coordinative functions by CNS damages were due to test substances, rota-rod test was performed using Rota-rod apparatus (Daejong, Seoul, Korea). The test apparatus for the locomotor activity test was designed to measure locomotor activity automatically using UV system (AM 1051, Benwick Electronics, Benwick, UK) when experimental animals moved in the chamber. In both tests, a group of mice were treated with negative control (vehicle, 1 mg/kg, i.p.), positive control (methamphetamine, 1 mg/kg, i.p.), or one of the three doses of test substances (0.1, 1, 5 mg/kg, i.p.) once every other day for 10 day

4. Drugs
The purpose of the present study was to assess the abuse liability of 5F-MDMB-PINACA, MDMB-CHIMICA, MDMB-FUBINACA, ADB-FUBINACA, and AMB-FUBINACA. The findings produce an apparent paradox, since CPP and self-administration predict with high reliability the likelihood that a compound will be abused by humans, and cannabinoids are well-known to produce active drug-seeking in humans. Drug discrimination is a well-known animal model of the subjective effects of drugs and correlates well with abuse liability (Young 2009; Horton et al. 2013). Assessment of abuse liability is based on several factors, including chemical structure, pharmacological mechanism of action, and finally, subjective and reinforcing behavioral effects (FDA, 2010; Swedberg, 2013).
Michael B Gat


Product ions detected at m/z 302, 217, and 145 (B2) confirmed that tert-leucine and indazole moieties remained unchanged, leading to the structure elucidation of a hydroxy-functional group at the 4-position of the butyl side chain by oxidative defluorination. The product ion m/z 336 (loss of methyl ester moiety) further confirmed the presence of dihydroxylated metabolites. The precursor ion, m/z 364 (B14, B5/B6) had a loss of 2 Da from m/z 366 indicated further dehydrogenation of the ester hydrolysis plus monohydroxylated metabolites. The presence of the product ion m/z 320, likely formed from a loss of carbon dioxide, indicated monohydroxylation at the tert-leucine in B8 (m/z 219), butyl side chain in B9 (m/z 145) and indazole moiety in B13 (m/z 161). The precursor ion, m/z 350 showed a loss of 14 Da explaining the hydrolysis of methyl ester from 4F-MDMB-BINACA.
Fig. 2.
The precursor ion m/z 396 (B10, B12/B15) was 32 Da higher than the parent drug, 4F-MDMB-BINACA, suggesting the addition of two hydroxy groups. All the below explanations for transformations into metabolites are based on the data shown in Fig. Metabolites were identified according to their precursor ions, product ions, and fragmentation patterns (Fig. 1). Traditional in-vivo metabolism studies to generate human metabolites of drugs relied heavily on the use of whole animal model systems, which are expensive, limited by drug administration amount, influenced by species variation and faced by many ethical issues. Eight in-vivo metabolites tentatively identified were mainly products of ester hydrolysis with or without additional dehydrogenation, N-dealkylation, monohydroxylation and oxidative defluorination with further oxidation to butanoic acid.
Fig. 1.
Monitoring metabolism of synthetic cannabinoid 4F-MDMB-BINACA via high-resolution mass spectrometry assessed in cultured hepatoma cell line, fungus, 4F ADB 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