The Encyclopedia of Psychoactive Plants: Ethnopharmacology and Its Applications

Catha edulis (Vahl) Forsskål ex Endlicher

 

Khat

 

Family

 

Celastraceae91 (Bittersweet Family); Subfamily Celastroideae, Celastreae Tribe

Forms and Subspecies

 

Khat farmers of Ethiopia make a distinction between two varieties: ahde, “white,” and dimma, “red,” in reference to the color of the leaves. The red leaves are said to be more potent (Getahun and Krikorian 1973, 359ff.). Apart from this, no varieties or forms have been described botanically (Brenneisen and Mathys 1992, 730).

Synonyms

 

Catha edulis Forsk.92

Catha forskalii A. Rich

Catha inermis G.F. Gmel.

Celastrus edulis Vahl

Dillonia abyssinica Sacleux

Trigonotheca serrata Hochst.

Folk Names

 

Abessinischer tee, Abyssinian tea, al-qât, Arabian tea, arabischer tee, Arab tea, bushman’s tea, cat, cath, chat, chat tree, flower of paradise, gat, jaad (Somali), jât, kafta (Arabic, “leaf”), kat, kât, kath, kathbaum, katstrauch, khat, khatstrauch, miraa, mirra, mirungi, muhulo (Tanzania), muirungi (Kenya), musitate (Uganda), qaad (Somali), qat, qât, qatbaum, qatstrauch, Somali tea, somalitee, thé des abyssins, tschat

History

 

The use of psychoactive khat leaves is very old, with roots that definitely predate coffee (Coffea arabica) drinking. It is very likely that khat was first chewed as an agent of pleasure and a stimulant93 in Ethiopia. The plant was first included in a list of medicines in 1222; it is also mentioned in the book The Wars of ‘Âmda Syon I (‘Âmda Syon I was a Christian king who ruled in the early fourteenth century) (Getahun and Krikorian 1973, 356). A history book by Al-Maqrîzî (1364–1442) notes the following about Abyssinian plants: “Among them is a tree that is called gât. It does not bear fruit, people eat its leaves, and these resemble the small leaves of the orange tree. They expand the memory and in doing so call the forgotten back into mind. They give pleasure and diminish the desire for food, sexuality, and sleep. For the inhabitants of that land, not to mention the educated, the consumption of this tree is associated with great longing” (Schopen 1978, 46f.).

The Sufis and the wandering dervishes played a great role in the early spread of khat use (Schopen 1981). They regarded the ingestion of the leaves as a sacred activity and used khat to achieve mystical experiences, believing that “[i]n doing so, you see things of rare knowledge that belong to God’s magnificence” (Schopen 1978, 52).

The name khat is apparently derived from the Arabic kut, “sustenance or driving principle,” or from the place name Kafa (in Ethiopia), which is also thought to be the source of the word coffee. Most folklore suggests that both the khat bush and the practice of chewing khat are from Yemen. It is said that the goatherd Awzulkernayien observed how his goats ate the leaves of a shrub, after which they behaved in a frisky manner. The goatherd then tried the fresh leaves, whereupon he immediately felt more awake and stronger than he ever had before. Before turning in to sleep that night, he chewed a few more of the leaves he had brought with him. He was unable to sleep the entire night and spent it instead in prayer and meditation. Following this, khat was proclaimed to be a sacred tree and regarded as a wondrous medicine (Getahun and Krikorian 1973, 353f.).

According to a different legend, two saints who often prayed throughout the night were constantly falling asleep or fighting to avoid sleep. They prayed to God that he would give them a means to prevent them from falling asleep. An angel appeared to them and showed them a plant to eat that would help them remain awake and pray through the night (Getahun and Krikorian 1973, 356).

Charles Musès has proposed the theory that khat was already regarded as a “food of the gods,” “divine food,” or “food of existence” in ancient Egypt and was used for magical purposes. The plant is thought to have been known as kht in Egyptian (Musès 1989). Others have suggested that the Homeric nepenthes was in fact khat. It has also been suggested that khat was the magical medicine Alexander the Great used to miraculously heal his troops. Even the smoke of Delphi (cf. Hyoscyamus albus) was said to have come from khat leaves and to have been inhaled as a psychoactive incense (Elmi 1983, 164).

The plant was described in 1775 by the Swedish botanist Pehr Forsskål (1732–1763), who lived in Yemen for many years and eventually died there. Pharmacognostic and chemical studies of the khat bush began in the German-language areas at the end of the nineteenth century (cf. Beitter 1900 and 1901). In the 1920s and 1930s, a variety of pharmaceuticals and agents of pleasure made from khat (e.g., Catha-Cocoa Milk; cf. Theobroma cacao) were sold in London (Brenneisen and Mathys 1992, 735). The beginnings of ethnographic khat research (in Yemen) began in the 1970s with the groundbreaking work of Armin Schopen (1978). It was only during the early 1980s that Swiss scientists discovered the actual psychoactive constituent, the amphetamine-like cathinone (Kalix 1981).

Distribution

 

The bush is very likely from the area around Lake Tana (Harar) in Ethiopia. From there, it spread to East Africa (via Kenya), Tanzania, Aden, Arabia, and Yemen (Getahun and Krikorian 1973). The khat bush can thrive in quite different ecological zones and can be found in both tropical and cooler mountain regions. The wild khat bush grows in the tropical rain forest of the Gurage country in Shewa, Ethiopia. It is cultivated in Arabia, Zambia, and Somalia, and even as far away as Afghanistan (Getahun and Krikorian 1973, 357).

Cultivation

 

Because the plant only rarely produces seeds in cultivation, khat is best propagated by cuttings (approximately 35 cm long) from the young branches. Propagation is best performed in a dry, hot climate (Grubber 1991, 43*). The cuttings—usually two—are placed in a hole filled with water. Khat can be planted at any time of the year, so long as the young plants can be provided with sufficient water. The bushes are planted in rows about 1 meter apart. Sorghum is often planted between the rows.

Propagation can also occur using seeds, but this is never done in the areas under cultivation (Getahun and Krikorian 1973:364).

Khat requires a climate that is the same as or similar to the climate required for growing coffee (Coffea arabica), i.e., approximately 1,200 mm of precipitation. As a mountain plant, the bush can tolerate a mild frost. The first harvest may be taken from the bush when it is three years old, although typically it is not taken until after five to eight years. Khat planting is done primarily by males (Getahun and Krikorian 1973, 365; R. Schröder 1991, 126*). Khat bushes are often inhabited by an insect of the genus Empoasca, although this does not cause damage. In fact, a greater number of young shoots (the best merchandise) are formed as a result of the insect eating the plant (Getahun and Krikorian 1973, 367).

Important areas of cultivation are found especially in Ethiopia and Yemen and now also in northern Madagascar, Afghanistan, Turkistan, and even Israel. Some 60% of the fertile areas of Yemen are used for planting khat (Brenneisen and Mathys 1992, 732).

Appearance

 

This evergreen, fast-growing bush can grow into a tree as large as an oak (15 to 20 meters tall); under cultivation, it usually is kept to a height of 3 to 5 meters or, in rare cases, 7 meters (Getahun and Krikorian 1973, 356). The more the bush is trimmed, the more rapidly young shoots appear.

On blooming branches, the leaves are always opposite, but they can be alternate on young branches and plants (Brennesien and Mathys 1992, 730; Krikorian 1985). The leaves have a serrated margin and a shiny, slightly leathery upper surface. Young leaves at the ends of branches are light green; older leaves are dark green. The leaves sometimes take on a red hue. The small, star-shaped flowers are white and are borne in clusters in axillary cymes. The fruit capsules are 7 to 8 mm long and have four chambers. When they mature, they open up like small flowers (Krikorian 1985).

The genus Catha consists of only a few species (Wang 1936), probably a maximum of three. The two others are Catha transvaalensis Codd. [syn. Catha cassinoides N.K.B. Robson] and Catha abbottii Van Wyk et Prins;94Catha spinosa Forssk. nows bears the botanically valid name Maytenus parviflora (Vahl) Sebsebe (Brenneisen and Mathys 1992, 730). These African bushes can all be mistaken for khat, although they themselves have no ethnopharmacological significance.

Psychoactive Material

 

—Leaves (Catha-edulis leaves, khat leaves)

—Fresh leaves and twigs, and also the leaf buds

—Dried leaves (khat tea)

 

Every day, large segments of the population of Yemen chew the light green leaves of the khat bush (Catha edulis) as a stimulant and inebriant.

 

 

The small fruits of Catha edulis.

 

Preparation and Dosage

 

The fresh leaves should be chewed as soon after harvesting as possible. They should be no more than two days old. They require no further treatment and do not need to be mixed with any other substances. A person simply takes as many of the leaves into the mouth as possible, then chews the leaves for some ten minutes before either spitting them out or swallowing them (Getahun and Krikorian 1973, 371). The juice of the chewed leaves is swallowed periodically (Schopen 1978, 85). The longer the constituent-rich juice is retained in the mouth, the more pronounced the effects. In Yemen, fresh leaves are also pounded in mortars.

The fresh leaves and branch tips are (more rarely) brewed or boiled into a tea. In South Africa, infusions of khat are known as bushman’s tea. In Yemen, roasted khat leaves were once used to prepare “coffee” (Schopen 1978, 86). They also can be ground, mixed with honey or sugar, and made into candies (Getahun and Krikorian 1973, 357). In Somalia, the leaves are sometimes dried in the sun and then crushed. Cardamom, cloves, and water are then mixed with the powder to produce a paste that is taken as a quid. Fresh or dried khat branches are added to tea (Camellia sinensis) for flavor. In Ethiopia, khat is even used to make mead: “The qât infusion is fermented with honey. This produces a brown, bitter, meadlike drink with mild inebriating effects” (Schopen 1978, 85).

In Arabia (Yemen), dried leaves are smoked both alone and with other substances, especially hashish (Cannabis indica; cf. also smoking blends) (Getahun and Krikorian 1973, 357). Dried leaves that are still green are used as a (medicinal) incense. The dried leaves may also be ground and formed into balls using a binding agent; when ingested, such preparations give strength to pilgrims bound for Mecca. Dried leaves can also be mixed with water to prepare a paste for ingestion by old people without teeth (Getahun and Krikorian 1973, 366).

Leaves that have been damaged by frost take on a dull ashen color and should not be used, as they are said to cause headaches (Getahun and Krikorian 1973, 367).

It is generally said that tobacco (Nicotiana tabacum) should be smoked along with khat, as it will potentiate the effects of the khat (Schopen 1978, 86).

Only the leaf buds, the young leaves, and the ends of the branches contain sufficient constituents. The main psychoactive component breaks down rapidly when the material is dried. In contrast, it can remain unchanged for months if the fresh leaves are frozen (Brenneisen and Mathys 1992, 732).

Between 100 and 200 g of leaves are typically consumed during a khat session (R. Schröder 1991, 127*). Ethiopian khat farmers eat between ¼ and ¾ kg of khat leaves in the morning—of the finest quality, to be sure (Getahun and Krikorian 1973, 374).

Cathinone, the primary active constituent, is some three times less toxic than amphetamine. An alcoholic extract of khat, in a dosage of 2 g per kilogram of body weight, has been demonstrated to have lethal effects on mice (Brenneisen and Mathys 1992, 738). One gram of khat leaves contain 3.27 mg of cathinone/cathine (Ahmed and El-Qirib 1993, 214).

Ritual Use

 

Most Muslims who live in areas where khat is grown regard both the bush and its leaves as sacred and utter a prayer of thanks before they use it (Getahun and Krikorian 1973, 356). In Ethiopia, traditionally only the older men chewed khat, and then only in conjunction with religious rites. They chewed the leaves and drank coffee so that they could remain awake for the long prayers. Often, they also smoked hashish on these occasions. Over the course of time, people began to chew khat leaves while watching over the sick, at marriages and funerals, and during business negotiations. Today, khat leaves are chewed by men and women of all ages, including students and children (Getahun and Krikorian 1973, 371f.).

Ethiopian dervishes use khat as part of their religious healing ceremonies. They chew consecrated leaves and then spit upon the ill before pronouncing prayers and magical formulae over them (Schopen 1978, 87).

In Yemen, the ritual use of khat is widespread for certain festivals and religious events: engagements, marriages, burials. Most Yemenites chew khat every day in a social round whose structure adheres to precisely defined ritual forms. Because of their socially integrative nature, these rounds play a central role in Yemenite society (Schopen 1978). The participants come together in the afternoon, during the “blue hour.” Most are men, but women occasionally take part as well. These daily khat rounds take place in the main rooms of private houses as well as in special khat rooms in the offices of the government, large companies, et cetera. The participants pluck fresh leaves from the twigs and stuff these into their mouths. The leaves are then moistened with saliva and chewed thoroughly. A pitcher of water is passed around continuously, “for the alkaloids work only when the cell juice of the leaves that have been mixed with saliva gets to the stomach by drinking” (R. Schröder 1991, 127*). Because tobacco (or, less often, hashish) smoking is regarded as an absolutely essential part of chewing khat, cigarettes, pipes, or the hoses of large water pipes are also passed around. The participants often sing and make music together. The activities change as the effects of the khat run their course. At first, the members of the round converse excitedly with one another about contemporary political topics, current events, gossip, and Islam. As the effects begin to diminish some two hours later, the participants weary and the conversations dwindle. At this time, the circle breaks up (Schopen 1978, 1981).

“We don’t have anything else to do so we sit and chew chat.”

 

AN ETHIOPIAN IN “CHAT: COFFEE’S RIVAL FROM HARAR, ETHIOPIA” (GETAHUN AND KRIKORIAN 1973, 374)

 

“Let the jewels of qât go around, emerald leaves of the small leaves.

Its ingestion sweetens my heart,

its sight my eye, my condition and my times are pleasant because of it.

Its hearts [i.e., the leaves]

bear the secrets that they place in our hearts.

They then flow into the most secret of thoughts.

[Qât is] the Burâq of the ascension of my heart,

as soon as it needs it.

Gabriel is my heart,

who travels to the highest heaven.

. . . . . . . . . . . . . . . . . . . . . . . . . .

Its use, say the Mursidûn [Sufis],

is like the enlightenment of the mysteries,

the seclusion of the forty days.

I have never wanted to ascend into the heaven of

my view in the universe, unless

I can make qât my ladder”

ABDALLÂH IBN AL-IMÂM SARAF AD-DÎN QASÎDE (SIXTEENTH CENTURY) (IN SCHOPEN 1978, 85)

 

Artifacts

 

In Yemen, numerous Arabic-language poems both glorify and criticize khat use (Schopen 1978). It is possible that many aspects of Arabic art have been influenced by the use of khat. The samar music of Yemen is composed specifically for the afternoon khat rounds and is played and sung during these social gatherings. At least one album of samar music that was recorded on-site has been released internationally: Music from Yemen Arabia: Samar(Lyrichord Discs, LLST 7284).

In Tanzania, the wood of the khat bush is used to manufacture spoons and combs (Schopen 1978, 86).

Medicinal Use

 

Khat is generally used only infrequently as a medicine. The leaves are mentioned in only two Arabic pharmacopoeias. Khat is said to calm the stomach and cool the intestines and is recommended for the treatment of depression and melancholy (Schopen 1978, 87). In Yemen, it is used also as an appetite suppressant (Fleurentin and Pelt 1982, 96f.*). More rarely, the fumes of burning khat are inhaled for the treatment of headaches (Schopen 1978, 88).

In Africa, khat root is used to treat influenza, stomach problems, and diseases of the chest (Getahun and Krikorian 1973, 357).

In Ethiopia, it is believed that khat can cure 501 diseases and afflictions, as the numerical value of its Arabic name, ga-a-t, is 400 + 100 + 1 (Getahun and Krikorian 1973, 370). Khat is also used there as an aphrodisiac (Krikorian 1984), as well as to treat depression and melancholy. A khat leaf is applied to the forehead as a remedy for headaches. Among the Masai and Kipsigi tribes, the leaves are used to treat gonorrhea. It is also said that regular consumption of khat provides protection against malaria. In Saudi Arabia, khat is used to treat asthma and fever (Brenneisen and Mathys 1992, 735).

Constituents

 

During the early phase of khat research, it was thought that the leaves contained caffeine, an assumption that none of the studies was able to verify. Later, katin (= cathine) or “celastrina” was regarded as the active principle (Krikorian and Getahun 1973, 379). Soon thereafter, it was suggested that ephedrine was responsible for the plant’s effects. Some investigators claimed that d-norpseudoephedrine was also present (Krikorian and Getahun 1973, 387). The constituents primarily responsible for the stimulating effects upon the central nervous system (CNS) are the khat phenylalkylamines or khatamines (phenylpropylamines) cathinone and cathine (= S,S-[+]-norpseudoephedrine) (Brenneisen and Geisshüsler 1985). Other CNS stimulants, the phenylpentylamines merucathine, pseudomerucathine, and merucathinone, are present in small amounts, and there is also some R,S-(–)-norephedrine (Brenneisen and Geisshüsler 1985, 293; Brenneisen et al. 1984). The actual primary psychoactive and stimulating constituent is cathinone (= S-(–)-cathinone or S-(–)-[alpha]-amino-propiophenone) (Brenneisen and Mathys 1992, 731; Kalix 1992).

The amount of constituents present in the fresh leaves can vary considerably, depending upon provenance, place of cultivation, age, and quality (Geisshüsler and Brenneisen 1987). The alkaloid content varies between 0.034% (leaves from Harar, Ethiopia) and 0.076% in leaves from Aden. Surprisingly, leaves from khat bushes grown in the United States and Europe have been found to contain little or almost no alkaloids (Krikorian and Getahun 1973, 379, 388). In leaves from Ethiopia, the cathinone content was measured as approximately 0.9 mg per leaf (fresh weight) (Halket et al. 1995, 111).

The flavonoid glycosides myricetin-3-O-β-D-galactoside, dihydromyricetin-3-O-rhamnoside, myricetin-3-O-rhamnoside, and quercetin-3-O-β-D-galactoside have been found in air-dried leaves and branch tips (Al-Meshal et al. 1986). These substances are similar to those contained in Psidium guajava.

Fresh leaves contain several polyphenolics (El Sissi and Abd Alla 1966). They are also rich in vitamins (especially vitamin C, but also thiamine, niacin, riboflavin, and beta-carotene) and minerals (Mg, Fe, Ca) as well as tannins, catechol tannins, sugars (mannitol, glucose, fructose, rhamnose, galactose, xylose), flavonoids, glycosides, amino acids (phenylalanine, choline, etc.), and proteins (Krikorian and Getahun 1973). There are also reports of an essential oil (Qédan 1972).

Effects

 

The primary effect of khat is an increase in energy and wakefulness (Widler et al. 1994). Khat chewing initially induces a cheerful mood, gaiety, and euphoria, together with a certain talkativeness. This state of arousal diminishes after about two hours. The stimulating effects usually begin with a tingling sensation on the head. It is said that khat “produces a social delirium” (Remann 1995, 79). The effect of the leaves is often compared to that of a “combination of caffeine and morphine” (R. Schröder 1991, 125*).

Sufis and dervishes use khat to produce an ecstatic state, but khat “will not induce this if the greatest intention is not present. If it does not appear, then you are negligent” (Schopen 1978, 200). In other words, ecstatic effects occur only when set and setting are taken into consideration.

“For centuries, khat has been used traditionally in Islamic cultures and tolerated by the Koran as a part of religious and social life. Consuming khat in groups is especially popular, as this is said to increase the ability to communicate and stimulate the fantasy and power of imagination. When working, khat is consumed individually, primarily for its performance-enhancing and hunger-suppressing effects.”

 

RUDOLF BRENNESIEN AND KAROLINE MATHYS CATHA

 

(1992, 735)

 

 

Cathinone

 

 

Cathine

 

Cathinone, the main active constituent, has been described as a “natural amphetamine” and has correspondingly similar effects (Kalix 1992). Cathinone interacts with the neurochemistry of dopamine (Pehek et al. 1990) and frees catecholamine at the synapses (Kalix 1992). It has the identical or at least very similar pharmacological properties and the same sympathomimetic effects as amphetamine (Kalix 1992; Widler et al. 1994). However, the effects of the leaves appear to be conditioned by the synergistic effects of cathinone and the other constituents (Krikorian and Getahun 1973, 278). Khat, or the mixture of substances contained in the leaves, also has interesting cholesterol-lowering effects (Ahmed and El-Qirib 1993, 215).

Apart from its psychoactive effects, khat also has an antidiabetic effect. Long-term chronic use can cause stomach problems, undernourishment, and nervousness. Ethiopian Christians claim that “insanity” is prevalent among Muslims because of their constant khat use (Krikorian and Getahun 1973, 378). A World Health Organization (WHO) document from 1964 notes, “Physical dependence (in the sense in which this is understood for morphine and substances with morphine-like effects or of the barbiturate type) does not occur [with khat], even when some tolerance to the effects has been acquired” (cited in Getahun and Krikorian 1973, 375).

Commercial Forms and Regulations

 

In Ethiopia, khat is divided into three commercial grades, depending upon the size and age of the leaves as well as their taste and tenderness: kudda (first quality), uretta (second quality), and kerti (third quality). In Kenya, a distinction is made between the qualities giza (best) and kangeta (lower quality). The best quality, giza-bomu, does not even make it to market because the plantation owners themselves consume it (Geisshüsler and Brenneisen 1987, 276). Some two hundred different sorts are recognized in Yemen (Schopen 1978, 66ff.). All the attempts to suppress khat use in Yemen or even to replace it with chewing gum (!) have—quite rightly—failed (Schopen 1978, 11).

Today, khat leaves are used in all those areas of the world in which ethnic groups from the traditional khat countries have settled. To serve them, shipments are sent by air freight daily to France, Italy, England, Switzerland,2 and even the United States. Around the world, some two to eight million portions of khat are chewed every day. The average price for a bundle of 50 g is approximately ten dollars (Brenneisen and ElSohly 1992, 99, 109).

In Arabia, the dried leaves are sold in supermarkets for use as tea (R. Schröder 1991, 127*). In contrast, the fresh leaves are forbidden, as they are in Djibouti (Brenneisen and ElSohly 1992, 111).

Upon the recommendation of WHO, cathi-none in its pure form was made an internationally controlled substance listed in Schedule I of the U.N. Convention on Psychotropic Substances (Brenneisen and ElSohly 1992, 109).

On the black market, one can occasionally find so-called khat pills (Nexus). Although the label often indicates that these pills contain extracts of Catha edulis, they actually consist of pure 2-CB, a synthetic phenethylamine with empathogenic effects (Schulgin and Schulgin 1991, 503ff.*).

“At exactly two o’clock in the afternoon, the proud Yemenite people roll down their store blinds and leave work to go straight to their inebriation, the qat inebriation. I have rarely seen a people who are as full of themselves as the Yemenite people are with qat. I have seldom encountered a people that could puff up its cheeks so mightily. With qat. Show me your cheeks, and I will tell you if you are from Yemen. Fat cheeks appear to be the primary physical effect of this people’s drug.”

 

MICKY REMANN

 

DER GLOBALTROTTEL [THE GLOBE-TROTTING MORON]

 

(1995, 79)

 

“The most common method of consuming khat is to chew it. As a part of the religious social life, khat was traditionally used in the Islamic cultures. Today, khat sessions are still subjected in part to strict, ritualized customs. . . .

 

“Khat use induces a general state of well-being. The consumers become cheerful, excited, and talkative. Problems appear to be more easily dealt with, the sense of space and time partially disappears, without hallucinations being produced. All tiredness vanishes and, as a result of the anorexic effect, all feelings of hunger as well.”

KAROLINE MATHYS “UNTERSUCHUNGEN DER PHARMAKOLOGISCHEN WIRKUNG VON CATHA EDULIS” [RESEARCH INTO THE PHARMACOLOGICAL EFFECT OF CATHA EDULIS] (1993, 6)

 

Literature

 

See also the entry for ephedrine.

 

Ahmed, M. B., and A. B. El-Qirbi. 1993. Biochemical effects of Catha edulis, cathine, and cathinone on adrenocortical functions. Journal of Ethnopharmacology 39:213–16.

 

Beitter, A. 1900. Pharmacognostisch-chemische Untersuchung der Catha edulis. Strassburg: Schlesier und Schweikhardt.

 

———. 1901. Pharmakognostisch-chemische Untersuchung der Catha edulisArchiv der Pharmazie 239:17–33.

 

Brenneisen, Rudolf, and Mahmoud A. ElSohly. 1992. Socio-economic poisons: Khat, the natural amphetamine. In Phytochemical resources for medicine and agriculture, ed. H. N. Nigg and D. Seigler, 97–116. New York: Plenum Press.

 

Brenneisen, Rudolf, and S. Geisshüsler. 1985. Psychotropic drugs. III: Analytical and chemical aspects of Catha edulis Forssk. Pharm. Acta Helvetica 60 (11): 290–301.

 

Brenneisen, Rudolf, S. Geisshüsler, and X. Schorno. 1984. Merucathine, a new phenylalkylamine from Catha edulisPlanta Medica 50:531.

 

Brenneisen, Rudolf, and Karoline Mathys. 1992. Catha. In Hagers Handbuch der pharmazeutischen Praxis, 5th ed., 4:730–40. Berlin: Springer.

 

Brilla, R. 1962. Über den zentralerregenden Wirkstoff der frischen Blätter von Catha edulis Forsskal. Dissertation, Bonn.

 

Brücke, Franz Th. von. 1941. Über die zentrale Wirkung des Alkaloids Cathin. Naunyn-Schmiedeberg’s Archiv für Experimentelle Pathologie und Pharmakologie 198:100–6.

 

Elmi, Abdullahi S. 1983. The chewing of khat in Somalia. Journal of Ethnopharmacology 8:163–76.

 

El Sissi, H. I., and M. F. Abd Alla. 1966. Polyphenolics of the leaves of Catha edulisPlanta Medica 14:76–83.

 

Friebel, H., and R. Brilla. 1963. Über den zentralerregenden Wirkstoff der frischen Blätter und Zweigspitzen von Catha edulis Forssk. Naturwissenschaften 50:354–55.

 

Geisshüsler, S. 1988. Zur Chemie, Analytik und Pharmakologie von Phenylalkylaminen aus Catha edulis Forssk. (Celastraceae). Dissertation, Bern.

 

Geisshüsler, S., and Rudolf Brenneisen. 1987. The content of psychoactive phenylpropyl and phenylpentenyl khatamines in Catha edulis Forssk. of different origin. Journal of Ethnopharmacology 19:269–77.

 

Getahun, Amare, and A. D. Krikorian. 1971. Chat: Coffee’s rival from Harar, Ethiopia. I: Botany, cultivation and use. Economic Botany 25:353–77.

 

Giannini, A., H. Bunge, J. Shasheen, and W. Price. 1986. Khat: Another drug of abuse? Journal of Psychoactive Drugs 18:155–58.

 

Halket, J. M., Z. Karasu, and I. M. Murray-Lyon. 1995. Plasma cathinone levels following chewing khat leaves (Catha edulis Forssk.). Journal of Ethnopharmacology 49:111–13.

 

Kalix, Peter. 1981. Cathinone, an alkaloid from khat leaves with amphetamine-like releasing effect. Psychopharmacology 74:269–79.

 

———. 1988. Khat: A plant with amphetamine effects. Journal of Substance Abuse Treatment 5:163–69.

 

———. 1990. Pharmacological properties of the stimulant khat. Pharmacology and Therapeutics 48:397–416.

 

———. 1992. Cathinone, a natural amphetamine. Pharmacology und Toxicology 70:77–86. (Excellent bibliography.)

 

Kennedy, John G. 1987. The flower of paradise: The institutionalized use of the drug qat in North Yemen. Dordrecht: D. Reidel Publishing.

 

Kennedy, John G., J. Teague, and L. Fairbanks. 1980. Qat use in North Yemen and the problem of addiction: A study in medical anthropology. Culture, Medicine and Psychiatry 4:311–44.

 

Krikorian, Abraham D. 1984. Kat and its use: A historical perspective. Journal of Ethnopharmacology 12:115–78.

 

———. 1985. Growth mode and leaf arrangement in Catha edulis (kat). Economic Botany 39 (4): 514–21.

 

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