Opioids

This article is a stub.

Classification

Classification by receptor affinity

• Opioid Agonists - Morphine, Codeine, Meperidine, Fentanyl, Sufentanil, Remifentanil, Methadone, Tramadol
• Opioid Agonist/Antagonists & Partial Agonists - Pentazocine, Nalbuphine, Butorphanol, Buprenorphine
• Opioid Antagonists - Nalorphine, Naloxone, Naltrexone, Naltrindole, Nalmefene

Classification by Exogenous Opioids Strength

According to the strength or potency based on the plasma concentrations at which they exert their effects. C₅₀ or the plasma concentration causing a 50% effect.

• Strong Opioids include fentanyl, sufentanil, and remifentanil
• Weak opioids include codeine and tramadol
• Intermediate group includes morphine, methadone, oxycodone, and buprenorphine

Classification by synthetic process

• Naturally occurring compounds - Morphine, Codeine, Thebaine, Papaverine
• Semi-synthetic compounds - Diamorphine (heroin), Dihydromorphone, Buprenorphine, Oxycodone
• Synthetic compounds - Pethidine, Fentanyl, Methadone, Alfentanil, Remifentanil, Tapentadol

Pharmacology

	Mu	Delta	Kappa
	Mu1 - Analgesia Mu2 - Sedation, vomiting, respiratory depression, pruritis, euphoria, anorexia, urinary retention, physical dependence.	Analgesia, spinal analgesia	Analgesia, sedation, dyspnoea, psychomimetic effects, miosis, respiratory depression, euphoria, dysphoria, dyspnoea
Endogenous Peptides
Enkephalins	Agonist	Agonist
B-Endorphin	Agonist	Agonist
Dynorphin A	Agonist
Agonists
Morphine	Agonist		Weak Agonist
Codeine	Weak Agonist	Weak Agonist
Fentanyl	Agonist
Meperidine	Agonist	Agonist
Methadone	Agonist
Antagonists
Naloxone	Antagonist	Weak Antagonist	Antagonist
Naltrexone	Antagonist	Weak Antagonist	Antagonist