Editing Khat (section)

==Chemistry and pharmacology==
[[File:S-Cathinone.svg|thumb|right|Cathinone structure]]
The stimulant effect of the plant was originally attributed to "katin", [[cathine]], a [[phenethylamine]]-type substance isolated from the plant. However, the attribution was disputed by reports showing the plant extracts from fresh leaves contained another substance more behaviourally active than cathine. In 1975, the related alkaloid [[cathinone]] was isolated, and its [[absolute configuration]], (S)-2-Amino-1-phenylpropan-1-one,<ref>[[cathinone]], IUPAC name</ref> was established in 1978. Cathinone is not very stable and breaks down to produce cathine and [[norephedrine]]. These chemicals belong to the [[phenylpropanolamine|PPA (phenylpropanolamine)]] family, a subset of the [[Substituted phenethylamine|phenethylamines]] related to [[amfetamine|amphetamines]] and the [[catecholamine]]s [[epinephrine]] and [[norepinephrine]].<ref name="drugs">{{cite web|url=https://www.drugs.com/npp/khat.html |title=Complete Khat Info |author=Drugs.com |date=1 January 2007}}</ref> In fact, cathinone and cathine have a very similar molecular structure to amphetamine.<ref name="cox2003">{{Cite journal|doi=10.1192/apt.9.6.456 |title=Adverse effects of khat: a review |year=2003 |last1=Cox |first1=G. |journal=Advances in Psychiatric Treatment |volume=9 |issue=6 |pages=456–63|doi-access=free }}</ref> Khat is sometimes confused with [[methcathinone]] (also known as ''cat''), a [[Convention on Psychotropic Substances#Schedules of Controlled Substances|Schedule I]] substance that possesses a similar chemical structure to the khat plant's cathinone active component. However, both the side effects and the addictive properties of methcathinone are much stronger than those associated with khat use.<ref name="Dfk">{{cite web|url=http://www.drugfree.org/drug-guide/khat |title=DF – Khat |website=Drugfree.org |access-date=26 January 2014}}</ref>

When khat leaves dry, the more potent chemical, cathinone, decomposes within 48 hours, leaving behind the milder chemical, cathine. Thus, harvesters transport khat by packaging the fresh leaves and stems in plastic bags or wrapping them in banana leaves to preserve their moisture and keep the cathinone potent. It is also common for them to sprinkle the plant with water frequently or use refrigeration during transportation.

When the khat leaves are chewed, cathine and cathinone are released and absorbed through the mucous membranes of the mouth as well as the lining of the stomach. The action of cathine and cathinone on the [[reuptake]] of [[epinephrine]] and norepinephrine has been demonstrated in lab animals, showing that one or both of these chemicals cause(s) the body to recycle these neurotransmitters more slowly, resulting in the wakefulness and insomnia associated with khat use.<ref>{{Cite journal|last1=Ahmed |first1=M.B. |last2=El-Qirbi |first2=A.B. |title=Biochemical effects of Catha edulis, cathine and cathinone on adrenocortical functions |journal=J Ethnopharmacol |volume=39 |issue=3 |pages=213–16 |date=August 1993 |pmid=7903110 |doi=10.1016/0378-8741(93)90039-8}}</ref>

Receptors for [[serotonin]] show a high affinity for cathinone, suggesting this chemical is responsible for feelings of euphoria associated with chewing khat. In mice, cathinone produces the same types of nervous pacing or repetitive scratching behaviours associated with amphetamines.<ref>{{cite web|url=https://www.ncbi.nlm.nih.gov/entrez |archive-url=https://web.archive.org/web/19970615054349/http://www.ncbi.nlm.nih.gov/Entrez/ |url-status=dead |archive-date=15 June 1997 |title=Behavioral Effects of Cathinone }}</ref> The effects of cathinone peak after 15 to 30 minutes, with nearly 98% of the substance metabolised into norephedrine by the liver.<ref name="cox2003" />

Cathine is somewhat less understood, being believed to act upon the [[adrenergic receptors]] causing the release of epinephrine and norepinephrine.<ref>{{Cite journal|last1=Adeoya-Osiguwa |first1=S.A. |last2=Fraser |first2=L.R. |title=Cathine, an amphetamine-related compound, acts on mammalian spermatozoa via beta1- and alpha2A-adrenergic receptors in a capacitation state-dependent manner |journal=Hum. Reprod. |volume=22 |issue=3 |pages=756–65 |date=March 2007 |pmid=17158213 |doi=10.1093/humrep/del454|doi-access=free }}</ref> It has a [[half-life]] of about three hours in humans. The medication [[bromocriptine]] can reduce cravings and withdrawal symptoms within 24 hours.<ref>{{Cite journal|last1=Giannini |first1=A. J. |last2=Miller |first2=N. S. |last3=Turner |first3=C. E. |title=Treatment of khat addiction |journal=J Subst Abuse Treat |volume=9 |issue=4 |pages=379–82 |year=1992 |pmid=1362228 |doi=10.1016/0740-5472(92)90034-L}}</ref>