Table 1. Synthetic compounds found in commercial products.
Affinity constants (Ki) and estimates relative to Δ9-THC (top) and efficacy (EC50) at CB1 receptors and estimates relative to the standard CB1 full agonist CP55,940 (bottom) at CB1 for SCBs JWH-018, AM-2201, UR-144 and XLR-11. Lower Ki values indicate higher affinity for the CB1 receptor. An efficacy equivalent (100%) to that of CP indicates full agonist effects at the CB1 receptor. Brents et al. (2011) and Chimalakonda et al. (2012) data were obtained in mouse whole-brain homogenates, while data from Wiley et al. (2013) were obtained from human cloned CB1 membranes. Assay conditions among laboratories will lead to variability in measures when the same compounds are tested, but the pattern of results is always the same: the SCBs in commercial preparations have higher affinity for CB1 receptors than Δ9-THC, and exhibit full agonist efficacy.
| Compound | CB1 affinity Ki (nM) | CB1 affinity (x THC) | Reference |
|---|---|---|---|
| THC | 15.29 | - | Brents et al., 2011; Chimalakonda et al., 2012 |
| JWH-018 | 1.22 | 12.53 | |
| AM-2201 | 0.40 | 38.71 | |
| THC | 67.00 | - | Wiley et al., 2013 |
| UR-144 | 24.00 | 2.79 | |
| XLR-11 | 29.00 | 2.31 | |
| Compound | CB1 efficacy EC50 (nM) | CB1 efficacy (% CP) | Reference |
| CP55,940 | 3.36 | - | Brents et al., 2011; Chimalakonda et al., 2012 |
| JWH-018 | 6.82 | 100 | |
| AM-2201 | ND | 100 | |
| CP55,940 | 25.00 | - | Wiley et al., 2013 |
| UR-144 | 159.00 | 100 | |
| XLR-11 | 98.00 | 100 |