Like morphine,<unk>  exerts its analgesic effects by acting as an agonist at the μ-opioid receptor.<unk>  is often employed in the treatment of postanesthetic shivering. The pharmacologic mechanism of this antishivering effect is not fully understood, but it may involve the stimulation of κ-opioid receptors.<unk>  has structural similarities to atropine and other tropane alkaloids and may have some of their effects and side effects. In addition to these opioidergic and anticholinergic effects, it has local anesthetic activity related to its interactions with sodium ion channels.<unk> 's apparent in vitro efficacy as an antispasmodic agent is due to its local anesthetic effects. It does not have antispasmodic effects in vivo.<unk>  also has stimulant effects mediated by its inhibition of the dopamine transporter (DAT) and norepinephrine transporter (NET). Because of its DAT inhibitory action,<unk>  will substitute for cocaine in animals trained to discriminate cocaine from saline. Several analogs of<unk>  such as 4-fluoropethidine have been synthesized that are potent inhibitors of the reuptake of the monoamine neurotransmitters dopamine and norepinephrine via DAT and NET. It has also been associated with cases of serotonin syndrome, suggesting some interaction with serotonergic neurons, but the relationship has not been definitively demonstrated. It is more lipid-soluble than morphine, resulting in a faster onset of action. Its duration of clinical effect is 120–150 minutes, although it is typically administered at 4– to 6-hour intervals.<unk>  has been shown to be less effective than morphine, diamorphine, or hydromorphone at easing severe pain, or pain associated with movement or coughing. Like other opioid drugs,<unk>  has the potential to cause physical dependence or addiction. It may be more likely to be abused than other prescription opioids, perhaps because of its rapid onset of action. A study which compared 75mg<unk>  administered via intravenous injection (IV) and 100mg administered orally (PO) to 15mg oxycodone (IV) and 10mg (PO), 10mg morphine (IV) and 20mg (PO), 2mg hydromorphone (IV) and 4mg (PO), and placebo (C) in the subject's self-reported subjective effects such as 'drug-liking' (how many of the subjects enjoyed or not, the experience; if yes, what was the most enjoyable part and why?, etc.) and how eagerly did subject 'want to re-experience it', and after IV doses were administered,<unk>  produced the 75mg second highest rates of 'drug-liking', after morphine 10mg. Morphine was described as more "sedating", "relaxing" and in comparison to the others, many subjects claimed that the experience was "more intense", "more profound",<unk>  followed, then hydromorphone, oxycodone and last was placebo. Upon oral administration, preference went from (greatest>least): oxycodone 10mg>morphine 20mg>hydromorphone 4mg>pethidine 100mg>placebo. With the exception of morphine,<unk>  was associated with more euphoria, difficulty concentrating, confusion, and impaired psychomotor and cognitive performance compared to hydromorphone, oxycodone, and placebo when administered (IV) to healthy volunteers. The especially severe side effects unique to<unk>  among opioids—serotonin syndrome, seizures, delirium, dysphoria, tremor—are primarily or entirely due to the action of its metabolite, norpethidine.
Pethidine
Esketamine
Ketamine
Fentanyl
Aceclidine
Nalorphine
Remifentanil
Procaine