Khat drug profile
Khat (also known as qat or chat) comprises the leaves and fresh shoots of Catha edulis Forsk, a flowering evergreen shrub cultivated in East Africa and the South-West Arabian Peninsula. Khat leaves are typically wrapped as a bundle in banana leaves. The principal active components in khat are cathinone and cathine (norpseudoephedrine) (see also Drug profile on synthetic cathinones). Chewing khat releases these substances into the saliva; they are rapidly absorbed and eliminated. Both cathinone and cathine are closely related to amphetamine, and the pharmacological effects of cathinone are qualitatively similar to those of amphetamine, although it is less potent. Only fresh leaves are chewed, because cathinone soon degrades into old or dry plant material. Analysis relies on the characteristic appearance of khat and the presence of cathinone and/or cathine. Khat is not under International control, but is scheduled by some Member States. Cathinone and cathine are listed in the 1971 United Nations Convention on Psychotropic Substances under Schedules I and III respectively.
Molecular structure: Cathinone
Molecular formula: C9H11NO
Molecular weight: 149.19 g/mol
Molecular structure: Cathine
Molecular formula: C9H13NO
Molecular weight: 151.21 g/mol
The principal active component in khat is S-cathinone, otherwise known as (-)-2-aminopropiophenone or, more formally, S-(-)-2-amino-1-phenyl-1-propanone. Cathinone is labile and is transformed within a few days of harvesting to a dimer (3,6-dimethyl-2,5-diphenylpyrazine). It is for this reason that khat needs to be consumed while still fresh. Cathine (1S, 2S-norpseudoephedrine), a further psychoactive substance, arises from the metabolism of cathinone in the mature plant. Apart from common plant products such as tannins, terpenes, flavonoids and sterols, a number of other substances occur in khat including smaller amounts of 1R, 2S-norephedrine and a large number of cathedulins (polyhydroxylated sesquiterpenes). Both cathinone and cathine are close chemical relatives of the phenethylamines. Thus cathinone is the β-keto analogue of amphetamine. A large number of synthetic cathinone derivatives have been produced, some of which have found use as active pharmaceutical agents.
Khat is usually supplied as a bundle of leaves and fresh shoots wrapped in banana leaves. It is reported to have a sharp taste and an aromatic odour. Alcoholic extracts (tinctures) of khat have occasionally been reported, especially in ‘herbal high’ sales outlets and at music festivals.
Both cathinone and cathine are central nervous system (CNS) stimulants, but have a lower potency than amphetamine. Khat consumption leads to effects that are qualitatively similar to those of amphetamine, i.e. increased blood pressure, a state of euphoria and elation with feelings of increased alertness and arousal. This may be followed by depression, irritability, anorexia and difficulty in sleeping. Frequent use of high doses may evoke psychotic reactions. Gastrointestinal effects include constipation and urine retention. The role of other constituents of the khat plant is less well understood. The euphoric effects of khat start after about one hour of chewing. Peak plasma levels of cathinone are obtained 1.5 to 3.5 hours after the onset of chewing. The mean plasma level may reach 100 ng/ml after chewing 60 g fresh khat for one hour. Cathinone is barely detectable in blood after eight hours. First-pass metabolism of cathinone in the liver leads to the formation of norephedrine. Only 2 % of cathinone is excreted unchanged in the urine. The elimination half-life of cathinone is 1.5 +/– 0.8 hours and that of cathine 5.2 +/– 3.4 hours. Specific associations have been proposed between khat consumption and myocardial infarction, liver failure and oral cancer, but in many cases confounding effects could not be eliminated.
Khat comprises the leaves and fresh shoots of Catha edulis Forsk, a flowering evergreen shrub cultivated in East Africa and the Arabian Peninsula. It is usually imported into Europe via air freight.
Although khat can be ingested as an infusion or smoked, by far the most common route of administration is to chew the plant. Fresh vegetable material (stems, leaves and flower buds) is chewed and the juice of the masticated material is swallowed, while the residues are spat out. Typically, an individual consumes 100–200 g of khat leaves (one bundle) in a session, and its effects last for several hours. Infusions from dried leaves are also consumed. With the exception of tobacco, the concomitant use of other drugs, including alcohol, by khat users is uncommon.
Khat is also known as qat, chat, miraa, murungu and Arabian or Abyssinian tea.
Although a bundle of khat appears reasonably characteristic, botanical and microscopic features are of limited use in confirming identity. It is usual for laboratory analysis to confirm the presence of cathinone and/or cathine.
Khat has been reviewed by the WHO Expert Committee on Drug Dependence (ECDD) on a number of occasions, the most recent assessment being made at the 34th meeting of ECDD in 2006. However, Catha edulis remains outside international control, although cathinone and cathine have been listed in the 1971 UN Convention under Schedules I and III respectively since the early 1980s. Khat is controlled in a number of European countries including Belgium, Denmark, Germany, Greece, France, Ireland, Italy, Latvia, Lithuania, Poland, Slovenia, Finland, Sweden, Norway, and Switzerland.
Khat is used as a traditional medicine by some indigenous people of East Africa, but neither khat nor its isolated active ingredients have been widely recognised for their therapeutic use.
In Germany, preparations of cathine containing up to 5 % as solution (maximum dose 1 600 mg per packaging unit) without any other narcotic substances or per unit dose up to 40 mg cathine, calculated as base, are exempted from special prescription and may be prescribed by ‘normal’ medical prescription. In the UK, khat is licensed as a medicinal product under the Medicines Act 1968, but to date it has not been imported as a medicinal product.
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