Pethidine

pethidine, known as meperidine in the united states (sold under the brand name demerol), is a synthetic opioid analgesic used for the treatment of moderate to severe pain. compared to traditional opioids such as morphine, pethidine was originially thought to be much safer and have less potential for abuse. it was later discovered that pethidine is significantly less safe than morphine and its metabolite norpethidine can be extremely toxic.

chemistry

pethidine is an opioid in the phenylpiperidine class.

pharmacology

opioids exert their effects by binding to and activating the μ-opioid receptor. this occurs because opioids structurally mimic endogenous endorphins which are naturally found within the body and also work upon the μ-opioid receptor set. the way in which opioids structurally mimic these natural endorphins results in their euphoria, pain relief and anxiolytic effects. this is because endorphins are responsible for reducing pain, causing sleepiness, and feelings of pleasure. they can be released in response to pain, strenuous exercise, orgasm, or general excitement. the bioavailability of orally administered pethidine can vary from 50% to around 60%.

compared to traditional opioids, pethidine has a very unique pharmacological profile. in addition to being an opioid, pethidine is also a muscarinic acetylcholine receptor antagonist. pethidine is also a dopamine reuptake inhibitor and norepinephrine reuptake inhibitor. pethidine is a κ-opioid agonist and its metabolite norpethidine is also an extremely powerful serotonin reuptake inhibitor.