Pharmacodynamics + Opioid activity of<unk>  and morphine Opioid Opioid receptor affinity (Ki, nM)<unk>  3.67 ± 0.7 31.9 ± 1.9 527 ± 70 Morphine 2.8 ± 0.2 55.96 ± 6.99 648.8 ± 59.7<unk>  acts as an opioid receptor receptor modulator. It is specifically a mixed agonist–antagonist or partial agonist of the μ- and κ-opioid receptors.<unk>  could also act as a biased agonist of the μ-opioid receptor, although more research is needed to confirm this. The binding affinity of<unk>  varies depending on the opioid receptor, with it having the highest affinity for the μ-opioid receptor, intermediate affinity for the κ-opioid receptor, and the lowest affinity for the δ-opioid receptor. In addition to its opioid activity,<unk>  has been found to act as a serotonin–norepinephrine reuptake inhibitor (SNRI), with pIC50 values of 5.86 for the serotonin transporter (SERT) and 5.68 for the norepinephrine transporter (NET). These actions theoretically might contribute to its analgesic efficacy.<unk>  is five times as potent as pethidine and one-fifth as potent as butorphanol as an analgesic. Due to its partial agonist nature at the μ-opioid receptor,<unk>  has significantly reduced side effects relative to opioid analgesics acting as full agonists of the receptor such as morphine. Moreover,<unk>  is not a controlled substance and there are no reports of addiction related to its use, indicating that, unlike virtually all other clinically-employed μ-opioid receptor agonists (including weak partial agonists like buprenorphine), and for reasons that are not fully clear, it is apparently non-addictive. This unique benefit makes long-term low-dose treatment of chronic pain and/or opioid dependence with<unk>  more feasible than with most other opioids. Despite having a stronger respiratory depressant effect than morphine,<unk>  shows a ceiling effect on its respiratory depressive action so above a certain dose this effect does not get any more severe. Pharmacokinetics<unk>  has an bioavailability by intramuscular injection of 97%. It has a mean t1/2α of fewer than two minutes, and its biological half-life is 2.2 hours.
Dezocine
Bremazocine
Eptazocine
Flumazenil
Midazolam
Ketazolam
Zotepine
Esketamine