Table 2.
Summary of MOR affinity (Ki), in vitro (EC50) and in vivo (ED50) potency measures obtained by means of radioligand binding experiments (3[H]DAMGO displacement), inhibition of forskolin-stimulated cAMP accumulation, and rat behavioral studies, respectively.
| MOR binding Ki (nM) | MOR potency EC50 (nM) | Antinociception ED50 (mg/kg) | Catalepsy ED50 (mg/kg) | |
|---|---|---|---|---|
| U-47700 | 14.3 (10.6–19.3) | 4.47 (3.86–5.16) | 0.405 (0.342–0.481) | 0.832 (0.644–1.07) |
| Etonitazene | 8.11 (5.17–12.6) | 0.0231 (0.0198–0.0270) | 0.00174 (0.00147–0.00206) | 0.00380 (0.00331–0.00438) |
| Isotonitazene | 11.2 (6.53–19.7) | 0.0536 (0.0448–0.0638) | 0.00704 (0.00562–0.00872) | 0.0134 (0.0115–0.0157) |
| N-desethyl isotonitazene | 1.53 (0.922–2.48) | 0.00413 (0.00327–0.00518) | 0.00298 (0.00234–0.00371) | 0.00696 (0.00581–0.00829) |
| Brorphine | 24.2 (17.9–32.7) | 2.06 (1.77–2.40) | 0.0858 (0.0752–0.0972) | 0.112 (0.0855–0.146) |
| Fentanyl | 6.35 (4.71–8.59) | 0.104 (0.0872–0.125) | 0.0209 (0.0192–0.0227) | 0.0359 (0.0273–0.0467) |
| Morphine | 5.48 (4.05–7.40) | 1.21 (1.06–1.38) | 4.10 (3.22–5.24) | 8.75 (7.53–10.1) |