11. Unlike most benzodiazepines, tifluadom has no activity at the ?-opioid receptor . 12. 6'- GNTI is an extremely biased agonist of the ?-opioid receptor . 13. Cyprodime is a selective opioid antagonist which blocks the ?-opioid receptors . 14. Cyprenorphine has mixed agonist antagonist effects at opioid receptors , like those of buprenorphine. 15. Additionally, opioid drugs suppress nociceptions by binding to endogenous opioid receptors . 16. Inflammatory pain is also blunted by endogenous opioid peptides activating peripheral opioid receptors . 17. The prototypical ?-opioid receptor agonist is morphine, the primary psychoactive alkaloid in opium. 18. Three known kinds of opioid receptors have been identified : delta ( ? ). 19. The four main opioid receptor types ( primitive jawless fishes. 20. Kyotorphin has an analgesic effect, but it does not interact with the opioid receptors .
