Editing Opium (section)

== Chemical and physiological properties ==
{{See also|Opioid|Opiate|Morphinan}}
<div class="skin-invert-image">{{multiple image
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 | image1            = Morphin - Morphine.svg
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 | caption1          = [[Morphine]] is the primary biologically active chemical constituent of opium
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 | caption2          = [[Codeine]] is another biologically active chemical constituent of opium
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Opium contains two main groups of [[alkaloid]]s. [[Phenanthrene]]s such as [[morphine]], [[codeine]], and [[thebaine]] are the main psychoactive constituents.<ref>{{cite web |url=http://www.homehealth-uk.com/medical/professional_drugtests_opiates.htm |title=Opiates |publisher=Homehealth-uk.com |access-date=October 7, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20111031001645/http://www.homehealth-uk.com/medical/professional_drugtests_opiates.htm |archive-date=October 31, 2011 |df=mdy-all }}</ref> [[Isoquinolines]] such as [[papaverine]] and [[noscapine]] have no significant [[central nervous system]] effects. Morphine is the most prevalent and important alkaloid in opium, consisting of 10–16 percent of the total, and is responsible for most of its harmful effects such as [[lung edema]], respiratory difficulties, coma, or cardiac or respiratory collapse. Morphine binds to and activates [[mu opioid receptor]]s in the brain, spinal cord, stomach and intestine. Regular use can lead to [[drug tolerance]] or [[physical dependence]]. Chronic opium addicts in 1906 China<ref name="McCoy opium" /> consumed an average of eight grams of opium daily; opium addicts in modern Iran<ref>{{cite web|url=http://www.caucaz.com/home_eng/breve_contenu.php?id=163|title=3 grams of opium for 1 dollar|author1=Max Chamka |author2=Translated by Geraldine Ring |publisher=Caucaz europenews|access-date=May 6, 2007}}</ref> are thought to consume about the same.

Both [[analgesia]] and [[drug addiction]] are functions of the mu opioid receptor, the class of [[opioid receptor]] first identified as responsive to morphine. Tolerance is associated with the superactivation of the receptor, which may be affected by the degree of [[endocytosis]] caused by the [[opioid]] administered, and leads to a superactivation of [[cyclic AMP]] signaling.<ref>{{cite journal |vauthors=Finn AK, Whistler JL |title=Endocytosis of the mu opioid receptor reduces tolerance and a cellular hallmark of opiate withdrawal |journal=Neuron |volume=32 |issue=5 |pages=829–39 |date=December 2001 |pmid=11738029 |doi= 10.1016/S0896-6273(01)00517-7|s2cid=16396686 |doi-access=free }}</ref> Long-term use of morphine in [[palliative care]] and the management of [[chronic pain]] always entails a risk that the patient develops tolerance or physical dependence. There are many kinds of [[Drug rehabilitation|rehabilitation treatment]], including pharmacologically based treatments with [[naltrexone]], [[methadone]], or [[ibogaine]].<ref>{{cite journal |vauthors=Alper KR, Lotsof HS, Kaplan CD |title=The ibogaine medical subculture |journal=Journal of Ethnopharmacology |volume=115 |issue=1 |pages=9–24 |date=January 2008 |pmid=18029124 |doi=10.1016/j.jep.2007.08.034 | s2cid =  2355108}}</ref>

In 2021, the [[International Agency for Research on Cancer]] concluded that opium is a Group 1 (sufficient evidence) human carcinogen, causing cancers of the larynx, lung, and urinary bladder.<ref>[https://monographs.iarc.who.int/news-events/volume-126-opium-consumption-2/ Volume 126: Opium Consumption] ''Volume 126: Opium Consumption''.</ref>