Plasma cathinone levels following chewing khat leaves (Catha edulis Forsk.)

Abuse Potential of Cathinones in Humans: A Systematic Review

Introduction and objective: Assessing the abuse potential of new substances with central nervous system activity is essential for preventing possible risks of misuse and addiction. The same methodology is recommended for the evaluation of the abuse potential of recreational drugs. This systematic review aims to assess the pharmacological effects related to the abuse potential and pharmacokinetics of cathinones, which are evaluated in both experimental and prospective observational studies in humans. Materials and Methods: A systematic search of the published literature was conducted to retrieve studies that had administered cathinone, mephedrone, methylone, and diethylpropion to evaluate their acute pharmacological effects related to abuse potential. Results: The search yielded 583 results, 18 of which were included to assess the abuse potential of cathinone (n = 5), mephedrone (n = 7), methylone (n = 1), and diethylpropion (n = 5). All four substances induce stimulant and euphorigenic effects that resemble those of amphetamines and MDMA, and their different intensities may be associated with varying levels of abuse potential. Conclusions: Cathinone, mephedrone, methylone, and diethylpropion induce a range of desirable and reinforcing effects that may, to some extent, result in abuse potential. Further investigation is needed to minimize and prevent their impact on society and public health.

Khat, a Cultural Chewing Drug: A Toxicokinetic and Toxicodynamic Summary

Khat (Catha edulis) is a recreational, chewed herbal drug that has been used as a psychostimulant for centuries in East Africa and the Arabian Peninsula, namely in Somalia, Ethiopia, and Yemen. However, the growing worldwide availability of khat has produced widespread concern. The plant comprises a large number of active substances, among which cathinone, cathine, and norephedrine are the main constituents, which can be included in the group of sympathomimetics of natural origin. In fact, these compounds are amphetamine analogues, and, as such, they have amphetamine-like nervous system stimulant effects. Chewing the leaves gives people a sensation of well-being and increases energy, alertness, and self-confidence. The chronic use of khat is, however, associated with severe cardiac, neurological, psychological, and gastrointestinal complications. The psychological dependence and withdrawal symptoms of khat are the reasons for its prolonged use. The aim of this paper is to review current knowledge on the khat plant with toxicokinetic and toxicodynamic perspectives. Namely, this review paper addresses in vitro, in vivo, and human studies. The models used, as well as the concentrations and doses with the respective biological effects, are discussed. Additionally, the main drug interactions involved with khat are described.

In vitro effects of 95% khat ethanol extract (KEE) on human recombinant cytochrome P450 (CYP)1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5

OBJECTIVES

Khat, a natural amphetamine-like psychostimulant plant, are widely consumed globally. Concurrent intake of khat and xenobiotics may lead to herb-drug interactions and adverse drug reactions (ADRs). This study is a continuation of our previous study, targeted to evaluate the in vitro inhibitory effects of khat ethanol extract (KEE) on human cytochrome (CYP) 1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5, major human drug metabolizing enzymes.

METHODS

In vitro fluorescence enzyme assays were employed to assess CYPs inhibition with the presence and absence of various KEE concentrations.

RESULTS

KEE reversibly inhibited CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 but not CYP1A2 with IC₅₀ values of 25.5, 99, 4.5, 21, 27, 17, and 10 μg/mL respectively. No irreversible inhibition of KEE on all the eight CYPs were identified. The K_i values of CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2 and CYP3A5 were 20.9, 85, 4.8, 18.3, 59.3, 3, and 21.7 μg/mL, respectively. KEE inhibited CYP2B6 via competitive or mixed inhibition; CYP2E1 via un-competitive or mixed inhibition; while CYP2A6, CYP2C8, CYP2C19, CYP2J2 and CYP3A5 via non-competitive or mixed inhibition.

CONCLUSIONS

Caution should be taken by khat users who are on medications metabolized by CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, and CYP3A5.

Effect of Regular Khat Chewing on Serum Fasting Sugar Level in Diabetic patients versus Healthy Individuals; A comparative study

Background

Khat chewing is a long standing social-cultural habit in several countries. Even though many people chew khat simply for its pleasurable and stimulatory effect, evidence showed widely-held belief among khat chewers in Ethiopia and other part of the world that khat helps to lower blood glucose while some studies are contradicted on the effect of khat. There is limited data about khat's effect on blood glucose especially in our setting, Harar estern Ethiopia.

Objective

Primarily the present study aims to compare fasting blood sugar level among khat chewer diabetic and healthy individuals, and to asses risk factors associated with poor glycemic control in diabetic subjects.

Method

A cross-sectional study included 200 confirmed diabetic and healthy subjects. Fasting blood sugar was determined by enzymatic method glucose oxidase and glucose hexokinase. Glycemic control was also determined for diabetic subjects based on the last 2-month diabetic clinic visits and current measurement.

Result

(Median ± IQR [interquartile range]) fasting blood sugar difference among Khat chewer and non khat chewer were 159 ± 83 mg/dl and 202 ± 79 mg/dl respectively in diabetic subjects when tested by glucose oxidase. Similarly, in healthy non khat chewer and khat chewer, khat chewers has lower (Median ± IQR) fasting blood glucose level 82 ± 18 mg/dl than non khat chewers 94 ± 13 mg/dl when tested by glucose oxidase. Regarding risk factors associated with poor glycemic control in diabetic subjects, positive parental diabetes history, insulin medication, being overweight, obese were significantly associated with poor glycemic control.

Conclusion

There was significant effect of khat on median FBS among khat chewers in diabetic and healthy individuals. And the proportion of glycemic control was high among diabetic subjects.

Recommendation

Health care professional and patients should manage the risk factors to delay disease progression and restrain the damage. More studies should be conducted in randomized control trial manner to further elucidate khat effect on blood sugar level so that the actual effect of khat can be identified unlike in cross sectional where there may not be strong causal relationship.

An updated review on synthetic cathinones

Cathinone, the main psychoactive compound found in the plant Catha edulis Forsk. (khat), is a β-keto analogue of amphetamine, sharing not only the phenethylamine structure, but also the amphetamine-like stimulant effects. Synthetic cathinones are derivatives of the naturally occurring cathinone that largely entered the recreational drug market at the end of 2000s. The former "legal status", impressive marketing strategies and their commercial availability, either in the so-called "smartshops" or via the Internet, prompted their large spread, contributing to their increasing popularity in the following years. As their popularity increased, the risks posed for public health became clear, with several reports of intoxications and deaths involving these substances appearing both in the social media and scientific literature. The regulatory measures introduced thereafter to halt these trending drugs of abuse have proved to be of low impact, as a continuous emergence of new non-controlled derivatives keep appearing to replace those prohibited. Users resort to synthetic cathinones due to their psychostimulant properties but are often unaware of the dangers they may incur when using these substances. Therefore, studies aimed at unveiling the pharmacological and toxicological properties of these substances are imperative, as they will provide increased expertise to the clinicians that face this problem on a daily basis. The present work provides a comprehensive review on history and legal status, chemistry, pharmacokinetics, pharmacodynamics, adverse effects and lethality in humans, as well as on the current knowledge of the neurotoxic mechanisms of synthetic cathinones.

Exploring the effect of khat (Catha edulis) chewing on the pharmacokinetics of the antiplatelet drug clopidogrel in rats using the newly developed LC-MS/MS technique

Clopidogrel (CLOP) is widely used worldwide for cardiovascular complications. CLOP is highly metabolized in the liver to its active metabolite by cytochrome P450 enzymes. Studies have shown that khat, an addictive substance, is a powerful inhibitor of cytochrome P450 enzymes and can influence the metabolism of drugs that are concomitantly used. Therefore, this study was designed to evaluate the effects of khat on the pharmacokinetics of CLOP in rats. In this study, rats were administered either CLOP alone or CLOP combined with khat and their plasma were obtained at different time intervals and analyzed using the newly developed and validated liquid chromatography with tandem mass spectrometry (LC-MS/MS) method using foretinib (FTB) as the internal standard. The corresponding peak area of the analyte versus FTB was used for calculating the peak ratio. The validated LC-MS/MS method resulted in the separation of the well-defined quantifiable peaks of CLOP, FTB, and CLOP metabolite within 7 min. Results showed a significant influence of khat on the peak ratio of CLOP metabolite, which was found to be significantly decreased (P < 0.05) in comparison to CLOP alone, suggesting significant decrease in the conversion of CLOP to its active metabolite due to the inhibition of CYP450 enzymes by khat. Therefore, there might be a need for dose adjustment for regular khat chewers using CLOP.

Khat use and psychotic symptoms in a rural Khat growing population in Kenya: a household survey

BACKGROUND

Khat is an amphetamine like psychostimulant chewed by over 10 million people globally. Khat use is thought to increase the risk of psychosis among its chewers. The evidence around this however remains inconclusive stemming from the scanty number of studies in this area and small study sample sizes. We undertook a large household survey to determine the association between psychotic symptoms and khat chewing in a rural khat growing and chewing population in Kenya.

METHODS

For this cross-sectional household survey, we randomly selected 831 participants aged 10 years and above residing in the Eastern region of Kenya. We used the psychosis screening questionnaire (PSQ) to collect information on psychotic symptoms and a researcher designed sociodemographic and clinical questionnaire to collect information on its risk factors. We used descriptive analysis to describe the burden of khat chewing and other substance use as well as rates and types of psychotic symptoms. Using a univariate and multivariate analyses with 95% confidence interval, we estimated the association between khat chewing and specific psychotic symptoms.

RESULTS

The prevalence of current khat chewing in the region was at 36.8% (n = 306) with a male gender predominance (54.8%). At least one psychotic symptom was reported by 16.8% (n = 168) of the study population. Interestingly, psychotic symptoms in general were significantly prevalent in women (19.5%) compared to men (13.6%) (p = 0.023). Khat chewing was significantly associated with reported strange experiences (p = 0.024) and hallucinations (p = 0.0017), the two predominantly reported psychotic symptoms. In multivariate analysis controlling for age, gender, alcohol use and cigarette smoking, there was a positive association of strange experiences (OR, 2.45; 95%CI, 1.13-5.34) and hallucination (OR, 2.08; 95% C.I, 1.06-4.08) with khat chewing. Of note was the high concurrent polysubstance use among khat chewers specifically alcohol use (78.4%) and cigarette smoking (64.5%).

CONCLUSIONS

Psychotic symptoms were significantly elevated in khat users in this population. Future prospective studies examining dose effect and age of first use may establish causality.

Challenges in Laboratory Detection of Unusual Substance Abuse: Issues with Magic Mushroom, Peyote Cactus, Khat, and Solvent Abuse

Drug abuse is a worldwide problem. Although commonly abused drugs can be identified during routine urine drug testing, less commonly abused drugs may escape detection. These less commonly abused drugs not only include some designer drugs such as synthetic cannabinoid but also include abuse of psychedelic magic mushroom (active ingredients: psilocybin and psilocin), peyote cactus (active ingredient: mescaline), and khat plants (active ingredient: cathinone). Moreover, solvent and glue abuse is gaining popularity among teenagers and young adults which may even cause fatality. Amphetamine/methamphetamine immunoassay has a low cross-reactivity with psilocin. Cathinone, if present in the urine, can be detected by amphetamine/methamphetamine immunoassay due to cross-reactivity of cathinone with assay antibody. Currently there is one commercially available immunoassay which is capable of detecting synthetic cathinone known as bath salts as well as mescaline. However, gas chromatography combined with mass spectrometry as well as liquid chromatography combined with tandem mass spectrometry (LC/MS/MS)-based method is available for confirmation of the active ingredients present in magic mushroom, peyote cactus, and khat plant. Such chromatography-based methods also offer more sensitivity and specificity compared to an immunoassay.

Isolation and in vitro permeation of phenylpropylamino alkaloids from Khat (Catha edulis) across oral and intestinal mucosal tissues

ETHNOPHARMACOLOGICAL RELEVANCE

Khat, the leaves of Catha edulis, is used as a "natural amphetamine-like" stimulant in eastern and southern Africa, as well as in the Arabian Peninsula. Leaves are masticated to elicit a state of euphoria. Although the psychostimulatory effects of the leaves are attributed to the presence of phenylpropylamino alkaloids (i.e. cathinone, cathine and norephedrine), the extent of permeation of these alkaloids across the oral and intestinal mucosa has not been established.

MATERIALS AND METHODS

Cathinone was isolated in the form of the oxalate salt from young buds, following acid-base extraction. High performance countercurrent chromatography (HPCCC) was used to isolate cathine and norephedrine, following borohydride reduction of a mixture of the three alkaloids. The in vitro permeability of these three alkaloids in their pure form, as well as in a crude extract, was evaluated across Caco-2 cell monolayers and across excised porcine intestinal, sublingual and buccal tissues.

RESULTS

The purities of the isolated cathine and norephedrine were in excess of 90%, thereby proving that HPCCC can be applied for efficient separation of these alkaloids from extracts of Khat. The apparent permeability (P_app) coefficients for the Khat alkaloids in their pure form were all above 1.0×10^-6cm/s, indicating that the transport of the three alkaloids across the selected biological membranes is comparable to that of the highly permeable reference compound, caffeine. Although readily transported across the various membranes, the alkaloids were transported to a lesser extent when present in a leaf extract, suggesting that other phytochemicals present in the extract influence their permeation.

CONCLUSIONS

These results provide evidence that chewing of Khat contributes to the buccal and sublingual absorption of the psychoactive alkaloids in the bloodstream directly across the oral mucosal membranes. In addition, it confirms that these metabolites will be readily absorbed from the gastrointestinal tract when swallowed.

Investigations of the genotoxic properties of two synthetic cathinones (3-MMC, 4-MEC) which are used as psychoactive drugs

Synthetic cathinones (SCAs) are consumed worldwide as psychostimulants and are increasingly marketed as surrogates of classical illicit drugs via the internet. The genotoxic properties of most of these drugs have not been investigated. Results of earlier studies show that amphetamines which are structurally closely related to these compounds cause damage to the genetic material. Therefore, we tested the genotoxic properties of two widely consumed SCAs, namely, 3-MMC (2-(methylamino)-1-(3-methylphenyl) propan-1-one) and 4-MEC (2-(ethylamino)-1-(4-methylphenyl) propan-1-one) in a panel of genotoxicity tests. We found no evidence for induction of gene mutations in Salmonella/microsome assays, but both drugs caused positive results in the single cell gel electrophoresis (SCGE) assay which detects single and double strand breaks of DNA in a human derived buccal cell line (TR146). 3-MMC induced similar effects as 4-MEC and also caused significant induction of micronuclei which are formed as a consequence of structural and chromosomal aberrations. Negative results obtained in SCGE experiments with lesion specific enzymes (FPG and Endo III) show that these drugs do not cause oxidative damage of DNA. However, moderate induction of TBARS (which leads to the formation of DNA-reactive substances) was observed with 4-MEC, indicating that the drug causes lipid peroxidation while no clear effect was detected with 3-MMC. Results obtained with liver homogenate in SCGE-experiments show that phase I enzymes do not lead to the formation of DNA reactive metabolites. Taken together, our findings indicate that consumption of certain SCAs may cause adverse health effects in users as a consequence of damage to the genetic material.

Khat (Catha edulis F.) and cannabinoids: Parallel and contrasting behavioral effects in preclinical and clinical studies

After a brief outline of Catha edulis F. (khat) and the cannabinoid systems, the interactions between the pharmacological effects of khat and cannabinoids will be reviewed. Khat chewing is a widespread habit that has a deep-rooted sociocultural tradition in Africa and the Middle East. Experimental studies conducted to investigate khat's central and peripheral effects have revealed an amphetamine-like mechanism of action mediated through the dopaminergic system. The endocannabinoid system comprises the receptors, the endogenous agonists and the related biochemical machinery responsible for synthesizing these substances and terminating their actions. Endocannabinoids are synthesized "on demand" from membrane phospholipids and then rapidly cleared by cellular uptake and enzymatic degradation. Khat and cannabinoids produce a body of parallel and contrasting behavioral effects. Concurrent consumption of khat and cannabinoids may increase the risk of getting or precipitating psychosis, has rewarding and motivational effect, increases the threshold of pain perception and impairs learning and memory. On the other hand, the action of cannabis to enhance food intake is likely to reduce khat's appetite suppressant effects.

Effect of Khat (Catha edulis) Use on the Bioavailability, Plasma Levels and Antimalarial Activity of Chloroquine

OBJECTIVES

This study aimed to evaluate the effect of khat (Catha edulis) on chloroquine (CQ) bioavailability in healthy Yemeni adults and its effect on CQ plasma levels and parasite clearance among malaria patients.

METHODS

This study took place between January and April 2007 in Bajil and Sana'a, Yemen. Two CQ doses (600 mg each) were given to 15 healthy males on separate occasions; the first dose was followed by a khat-chewing session (phase one) while controls abstained from khat-chewing for the second (phase two). Additionally, 103 patients with Plasmodium falciparum-induced malaria, including both regular khat chewers (n = 57) and non-khat chewers (n = 46), were treated with CQ (25 mg/kg) over three days. Pharmacokinetic parameters were analysed among both controls and malaria patients. Parasite clearance was also investigated for the latter group.

RESULTS

The mean area under the concentration-time curve (AUC) was 2,108.9 versus 2,797.4 ng/hour/mL, mean peak plasma concentration (Cmax) was 415.6 versus 508.7 ng/mL and mean time to reach Cmax was 3.8 versus 3.6 hours for controls in phase one versus phase two, respectively; both AUC and Cmax levels were significantly reduced by khat-chewing (P <0.050). For khat- versus non-khat-chewing malaria patients, mean plasma CQ concentrations were 266.4 ng/mL versus 427.5 ng/mL (P <0.001). Furthermore, CQ was effective in 71.7% and 75.4% of non-khat and khat-chewing malaria patients, respectively (P = 0.823).

CONCLUSION

Khat-chewing was found to significantly reduce plasma CQ levels among healthy volunteers and malaria patients. While receiving CQ treatment, patients should be advised not to chew khat.

"Natural Amphetamine" Khat: A Cultural Tradition or a Drug of Abuse?

Khat, Catha edulis Forsk, is among the most widely used plant-based psychoactive substance in the world. Grown in Eastern Africa, Horn of Africa, and southwestern part of the Arabian Peninsula, its fresh young leaves and twigs are used daily by over 20 million people for the psychostimulatory effects it produces in the user, a practice deeply rooted in the history, tradition, and culture of the indigenous population. Once hardly known outside the regions where it is grown and used, khat use has now spread to other countries. This review will cover the, phytochemistry, pharmacokinetics of the active ingredients-cathinone, cathine, norephedrine, neurochemistry, effects on cognitive and executive functions as well as its ability to produce dependency in the user. Whether it is an innocuous cultural practice or a drug of abuse is debatable as the preclinical and clinical data needed to arrive at an authoritative conclusion is lacking.

Khat and synthetic cathinones: a review

For centuries, 'khat sessions' have played a key role in the social and cultural traditions among several communities around Saudi Arabia and most East African countries. The identification of cathinone as the main psychoactive compound of khat leaves, exhibiting amphetamine-like pharmacological properties, resulted in the synthesis of several derivatives structurally similar to this so-called natural amphetamine. Synthetic cathinones were primarily developed for therapeutic purposes, but promptly started being misused and extensively abused for their euphoric effects. In the mid-2000's, synthetic cathinones emerged in the recreational drug markets as legal alternatives ('legal highs') to amphetamine, 'ecstasy', or cocaine. Currently, they are sold as 'bath salts' or 'plant food', under ambiguous labels lacking information about their true contents. Cathinone derivatives are conveniently available online or at 'smartshops' and are much more affordable than the traditional illicit drugs. Despite the scarcity of scientific data on these 'legal highs', synthetic cathinones use became an increasingly popular practice worldwide. Additionally, criminalization of these derivatives is often useless since for each specific substance that gets legally controlled, one or more structurally modified analogs are introduced into the legal market. Chemically, these substances are structurally related to amphetamine. For this reason, cathinone derivatives share with this drug both central nervous system stimulating and sympathomimetic features. Reports of intoxication and deaths related to the use of 'bath salts' have been frequently described over the last years, and several attempts to apply a legislative control on synthetic cathinones have been made. However, further research on their pharmacological and toxicological properties is fully required in order to access the actual potential harm of synthetic cathinones to general public health. The present work provides a review on khat and synthetic cathinones, concerning their historical background, prevalence, patterns of use, legal status, chemistry, pharmacokinetics, pharmacodynamics, and their physiological and toxicological effects on animals and humans.

Khat as a risk factor for hypertension: A systematic review

BACKGROUND

Studies suggest possible newer risk factors for hypertension including Khat chewing, a plant which grows wild in countries bordering the Red Sea and along the east coast of Africa and the Arabian Peninsula.

OBJECTIVES

The objective was to synthesise the best available evidence on the epidemiological association between Khat chewing as exposure (potential risk factor) and hypertension.

INCLUSION CRITERIA

Subjects aged 16 years old or older regardless of gender and ethnicity, country of residence, Khat dose, frequency, duration of chewing or other characteristics of Khat exposure and co-presence of other known risk factors for hypertension.The focus of interest of this review was the epidemiological association between Khat chewing as exposure (potential risk factor) and hypertension as an outcome.Observational analytical studies (cohort studies, case-control studies and cross-sectional studies) were considered for inclusion.

SEARCH STRATEGY

Three staged search strategy was used to identify all relevant published and grey literature in English language from 1988 to 2011. Databases searched were PubMed, CINAHL, PopLine, LILACS, MedNar and Embase.

METHODOLOGICAL QUALITY

All papers selected for inclusion in the review were subjected to a rigorous, independent appraisal by the two reviewers prior to inclusion in the review using standardised critical appraisal instruments from the Joanna Briggs Institute.

DATA COLLECTION AND SYNTHESIS

Due to poor internet service in our setting we were unable to use the Joanna Briggs Institute -software for data extraction and synthesis as approved in the protocol. Quantitative papers were pooled in statistical meta-analysis using the Review Manager Software. Odds ratios and their 95% confidence intervals were calculated for analysis.

RESULTS

Two studies from Ethiopia and one from Saudi Arabia were identified. In the study done by Getahun et al. 44 of the chewers (n=324) and 34 of the non chewers (n=319) were found to have hypertension. Analysis of this study showed no statistically significant association between Khat chewing and hypertension (OR=1.29, 95% CI =0.80-2.08). In the second study done by Mossie, 29 of the chewers (n=277) and 73 of the non chewers (n=621) were found to have hypertension and there was no statistically significant association between Khat chewing and hypertension (OR=0.88, 95% CI =0.56-1.38). Seventy seven of the chewers (n=568) and 160 of the non chewers (n=1207) were found to have hypertension) in the third study done by Ibrahim, similarly there was no statistically significant association between Khat chewing and prevalence of hypertension (OR=1.03, 95% CI =0.77-1.37 in this study.On meta analysis, a total of 3321 subjects were involved. Of the Khat chewers (1174), 150 were found to have hypertension. On contrary, 267 of non chewers (2147) were found to have hypertension. Finding of the analysis showed no statistically significant association between Khat chewing and hypertension (Odds ratio=1.04, 95% Confidence Interval= 0.84, 1.29). The studies were homogenous, Heterogeneity test: Chi = 1.35, df = 2, (P = 0.51). The test for overall effect also showed no statistical significance at conventional levels (P>0.05).

CONCLUSIONS

We did not find sufficient evidence to conclude that Khat as epidemiologic risk factor for hypertension.The present systematic review did not identify a statistically significant association of Khat chewing as epidemiologic risk factor for hypertension.

IMPLICATIONS FOR RESEARCH

This review identifies the need for further studies on Khat as an epidemiologic risk factor for hypertension considering further aspects of chewing, like dose-response, duration of chewing and co-existence of other co-morbid factors of hypertension.

Khat chewing, cardiovascular diseases and other internal medical problems: the current situation and directions for future research

The leaves of khat (Catha edulis Forsk.) are chewed as a social habit for the central stimulant action of their cathinone content. This review summarizes the prevalence of the habit worldwide, the actions, uses, constituents and adverse health effects of khat chewing. There is growing concern about the health hazards of chronic khat chewing and this review concentrates on the adverse effects on health in the peripheral systems of the body, including the cardiovascular system and gastrointestinal tract. Comparisons are made with amphetamine and ecstasy in particular on the detrimental effects on the cardiovascular system. The underlying mechanisms of action of khat and its main constituent, cathinone, on the cardiovascular system are discussed. Links have been proposed between khat chewing and the incidence of myocardial infarction, dilated cardiomyopathy, vascular disease such as hypertension, cerebrovascular ischaemia and thromboembolism, diabetes, sexual dysfunction, duodenal ulcer and hepatitis. The evidence, however, is often based on limited numbers of case reports and only few prospective controlled studies have been undertaken. There is therefore an urgent need for more thorough case-control studies to be performed. This review outlines the current knowledge on the adverse health effects of khat chewing on the cardiovascular system and other internal medical problems, it assesses the evidence and the limitations of the studies and identifies the questions that future studies should address.

The Health Effect of Psychostimulants: A Literature Review

Prevalence of psychostimulant use is high, and raising in several countries. Nicotine is the legal stimulant causing the most important public health impact. Cocaine ranks among the most used illicit substances after cannabis. Stimulant medications are frequently misused. Psychostimulants can lead to addiction, have physical, psychological and social health consequences and can induce a great disease burden. The aim of the present article is to provide a literature review on the health effects of stimulants as potential drugs of abuse. It will cover essentially cocaine, amphetamines and its derivatives (including methamphetamines and 3-4-methylenedioxymethamphetamine, ecstasy), nicotine, caffeine and khat, and touch upon the issues of prescribed substances (anti-depressants, weight control medications, attention-deficit hyperactivity disorder medications, hypersomniac disorder). Their pharmacology, addictive potential, health consequences and treatment will be discussed. We used Medline for the literature review from 1990 to the date of this review, and mention the findings of human and animal studies (the latter only if they are of clinical relevance).

Khat - a controversial plant

Khat (Catha edulis) is a shrub or tree whose leaves have been chewed for centuries by people who live in the Eastern part of Africa and the Arabian Peninsula. It has recently turned up in North America and Europe, particularly among emigrants and refugees from countries such as Somalia, Ethiopia and Yemen. Khat contains a number of chemicals, among which are two controlled substances, cathinone (Schedule I) and cathine (Schedule IV). Both chemicals are stimulant drugs with effects similar to amphetamine. Chewing the leaves makes people feel more alert and talkative, and suppresses appetite. Chewing khat leaves releases cathinone, a stimulant that produces the feeling of euphoria. When cathinone is broken down in the body, it produces chemicals including cathine and norephedrine, which have a similar structure to amphetamine and adrenaline (epinephrine). Regular khat use is associated with a rise in arterial blood pressure and pulse rate, corresponding with levels of cathinone in the plasma. Moreover, regular khat chewers have gingivitis and loose teeth, but there appears to be no convincing unusual incidence of oral cancer. Among khat users in Yemen there is, however, a higher incidence of esophageal cancer compared with gastric cancer. Long term use or abuse can cause insomnia, anorexia, gastric disorders, depression, liver damage and cardiac complications, including myocardial infarction. Manic and delusional behavior, violence, suicidal depression, hallucinations, paranoia and khat-induced psychosis have also been reported. On the basis of the scientific data it seems clear that khat use has negative consequences on the economic development of a country and on the health of the society.

Proconvulsant effect of khat (Catha edulis) in Sprague dawley rats

ETHNOPHARMACOLOGICAL RELEVANCE

Catha edulis (khat) is a plant whose fresh young leaves are used by an estimated five million people in eastern Africa and the Arabian Peninsula as a drug of recreation. The fresh leaves and shoots are rich in cathinone, a psychostimulant with effects similar to those of amphetamines. Psychostimulants produce a dose-related excitation of the central nervous system which can lead to seizures and convulsions. However there are no reports on studies of the effect of this herb on brain excitability and seizures. This knowledge is useful for doctors who may prescribe drugs whose side effects include lowering seizure threshold because there could be additive proconvulsant effect among khat users.

AIM OF THE STUDY

to determined whether khat lowers pentylenetetrazole (PTZ) seizure threshold.

METHODOLOGY

Male Sprague dawley rats were given fresh aqueous khat extract, old aqueous khat extract (3 g/kg bw), methylphenidate or saline and the timed intravenous (PTZ) seizure threshold test was used to study its effect on seizure threshold.

RESULTS

Fresh khat (3 g/kg) and methylphenidate (4 mg/kg) lowered PTZ seizure threshold.

CONCLUSION

Khat lowers seizure threshold.

Illicit cathinone (“Hagigat”) poisoning

INTRODUCTION

Khat leaves (mainly cathinone and cathine) have been chewed for centuries as stimulants. Hagigat (capsules of 200 mg cathinone) have been marketed in Israel as a natural stimulant and aphrodisiac. The consequences of illicit exposure to cathinone are reported.

METHODS

Prospective observational study of calls to the Poison Center regarding exposure to Hagigat during the course of 10 months. Demographic and clinical data were abstracted from patients' records and telephone follow up was performed.

RESULTS

Data of 34 consecutive patients aged 16-54 years were analyzed. The amount consumed was (1/2)-6 capsules (ingestion-32, sniffing-2). Main clinical manifestations were headache, vomiting, hypertension, nausea, tachycardia, dyspnea, chest pain, and myalgia. Main complications were myocardial ischemia (3), pulmonary edema (2), and intracerebral hemorrhage (1), all in young subjects. Treatment was supportive; one patient underwent neurosurgery.

CONCLUSION

Exposure to illicitly synthesized cathinone is associated with serious cardiovascular and neurological toxicity, even in young subjects.

Risk assessment of khat use in the Netherlands: a review based on adverse health effects, prevalence, criminal involvement and public order

In preparing a decision about the legal status of khat in the Netherlands, the Dutch Minister of Health requested CAM (Coordination point Assessment and Monitoring new drugs) to assess the overall risk of khat in the Netherlands. The present paper is a redraft of a report which formed the scientific basis of the risk evaluation procedure (October 2007). This report reviews the scientific data about khat available in the international literature. In addition, the report contains some information specific for the Netherlands (prevalence, availability of khat and public order aspects). The main psychoactive compounds in khat leaves are cathine and cathinone, which are some 2- to 10-fold less active than amphetamine. Acute health problems are rarely seen, and are usually related with malnutrition, social and financial problems. Khat has a low addictive potential. Chronic toxicity of khat is modest when used in low amounts, whereas at high levels, khat use is associated with adverse effects, like hypertension, heart rhythm disorders, insomnia and loss of appetite. In addition, khat users show a higher prevalence of cancers in the digestive tract. At population level, khat does not lead to specific health risks in the Netherlands, as its use is confined to East-African immigrants. A relationship between khat use and psychiatric disorders has been suggested, but the reports are contradictory, and such studies are presumably heavily confounded by posttraumatic and social stress. In the Netherlands (and other countries), khat use occasionally leads to minor disturbance of civil order in the public domain (loud talking, spitting), but is not related to criminal activities. Following the assessment, CAM estimated the overall risk potential of khat use in the Netherlands as very low. A similar conclusion may be drawn for countries with a comparable prevalence of khat use and khat related public order disturbance.

The effect of Khat (Catha edulis) as an appetite suppressant is independent of ghrelin and PYY secretion

BACKGROUND

The leaves of the khat plant (Catha edulis) are chewed for their pleasurable effects. Chewing releases cathinone which may decrease appetite through an unknown mechanism. Levels of the peptide ghrelin increase with hunger and decrease immediately post-prandially, while peptide YY is released following a meal. We hypothesised that the anorexigenic effects of khat may be mediated through changes in these hormones.

MATERIALS AND METHODS

Six habitual khat chewers attended on two separate occasions. For a period of 3h they chewed either khat leaves or lettuce. Blood pressure (BP) and pulse rate (PR) were monitored throughout, as were subjective assessments of hunger and fullness. Plasma samples were analysed for cathinone, ghrelin and PYY levels.

RESULTS

Chewing khat significantly decreased subjective feelings of hunger and increased fullness (p<0.05) but had no effect on ghrelin and PYY levels. Khat led to an increase in cathinone levels as well as an increase in BP and PR. Cathinone levels correlated positively with fullness and pulse rate and negatively with hunger.

CONCLUSIONS

Chewing khat decreases subjective feelings of hunger and increases systemic sympathetic tone, but has no effect on ghrelin and PYY levels. We conclude that the anorexigenic effect of khat may be secondary to central mechanisms mediated via cathinone.

A review of the neuropharmacological properties of khat

BACKGROUND

The psychostimulant khat (Catha edulis Forsk), is a herbal drug cultivated and chewed as a recreational and socializing drug in East Africa and the Arabian Peninsula for centuries. Due to increasing air transportation and the loosening of customs restrictions, it is now readily available in the Western Countries mainly used by immigrants from khat growing areas causing a concern to policy-makers.

OBJECTIVE

We conducted this review to further gain an insight to the neuropharmacological effects of khat.

METHODOLOGY

PubMed search engine with key terms 'khat' or 'qat' or 'mirra' or'qaad/jaad' or 'cathinone' was used to obtain articles relevant to khat chewing. In total 284 English written articles published from 1959 to 2007 were screened.

RESULTS

Most of the studies focused on cathinone, the postulated active psychostimulant alkaloid in khat. There were few studies which investigated the entire plant extract in either in vitro or animal studies. In the majority of the studies it was reported that both cathinone and cathine, another psychoactive constituent, have actions that are similar to those of amphetamine.

CONCLUSIONS

It seems that the well investigated khat alkaloids have many features similar to amphetamines; however there is a need for a more thorough examination of khat itself in well designed in vitro, animal and human studies with a range of comparator drugs before confirming the claim that khat is a "natural amphetamine".

Khat chewing from the pharmacological point of view: an update

Khat chewing is deeply rooted in the every day life of people living in the Horn of Africa and in South Arabia, where Catha edulis is endemic. Considered little more than an exotic habit producing just mild pharmacological effects, systematic investigations on its active principles have instead lead to the isolation and chemical characterization of cathinone, a compound structurally related to amphetamine. Three decades of intense experimental and clinical research on khat have depicted a consistently clear picture of its pharmacological and toxicological effects.

Vasoconstriction of porcine left anterior descending coronary artery by ecstasy and cathinone is not an indirect sympathomimetic effect

3,4-methylenedioxymethamphetamine ('Ecstasy', MDMA) and cathinone, the active constituent of khat leaves, were examined on pig isolated left anterior descending coronary arteries to determine whether they cause vasoconstriction and whether this was an indirect sympathomimetic action. Coronary artery rings were set up in Krebs solution (37 degrees C) gassed with 5% CO2 in O2. Endothelium remained intact as indicated by relaxation by bradykinin. Isometric tension was recorded and cumulative concentration-response curves (CRCs) for noradrenaline, ecstasy or cathinone plotted as a percent of the constriction to KCl (60 mM). Noradrenaline-induced contractions of the coronary artery were enhanced by propranolol (1 microM) indicating beta-adrenoceptor-mediated opposing vasodilatation. Cocaine (10 microM) further potentiated, while prazosin (1 microM) virtually abolished the contractions to noradrenaline. Cathinone and ecstasy constricted the coronary artery rings, the peak contractions being 56.5+/-4.2% (n=4) and 37.3+/-2.4% (n=4), respectively. Higher concentrations relaxed. The vasoconstriction was not affected by cocaine (10 microM), prazosin (1 microM, in the presence of cocaine) or removal of the endothelium. There was no tachyphylaxis or desensitisation on repeated administration of single doses. Ecstasy- and cathinone-induced coronary vasoconstriction is therefore via mechanisms other than indirect sympathomimetic activity or alpha1 -adrenoceptors. This activity could explain the cardiac adverse effects following their excessive use.

The potential adverse effects of habitual use of Catha edulis (khat)

The habit of Catha edulis Forsk (khat) chewing has prevailed for centuries among populations in the horn of Africa and the Arabian peninsula. Fresh leaves of Catha edulis are customarily chewed to attain a state of stimulation. The fact that cathinone has a closer structural similarity with amphetamine, and both share common pharmacodynamic features, led to the conclusion that cathinone is the most important active ingredient of Catha edulis, which causes the major pharmacological effects. Problems associated with repeated consumption of Catha edulis leaves are becoming evident. Literature surveys and clinical diagnostic studies revealed an association with prevalence of psychiatric morbidity. Repeated intermittent oral administration of Catha edulis to laboratory animals lead to development and expression of locomotor sensitisation. Catha edulis also leads to several peripheral effects that include increases in blood pressure and has been associated with the increased incidence of acute coronary vasospasm and myocardial infarction. Catha edulis also accounts for a number of gastrointestinal tract problems, oesophagitis, gastritis and delay intestinal absorption, as well as the development of oral keratotic white lesions at the site of chewing. Administration of Catha edulis extracts showed a deranged systemic capacity to handle oxidative radicals and induces cytotoxic effects in cells of liver and kidney, as well as induction of cell death in various human leukaemia cell lines and in peripheral human blood leukocytes.

Oral white lesions associated with chewing khat

Introduction

Khat is a cultivated plant whose leaves when chewed elevate mood. Unlike the chewing of betel nut, no association between the white oral mucosal lesions in khat users and oral malignancies has been reported. Chewing of khat has been documented in many countries and has increased with worldwide migration. The impact of chewing khat upon the oral mucosa is essentially unknown.

Purpose

The purpose of this study was to assess the occurrence of oral white changes in chronic khat chewers. Oral mucosal changes in a group of 47 Yemenite Israeli men over 30 years of age, who had chewed khat more than 3 years, were compared to those of 55 Yemenite men who did not chew.

Results

White lesions were significantly more prevalent in the khat chewers (83%) compared to the non chewing individuals (16%) (P < 0.001). White oral lesions were identified primarily on the lower buccal attached gingival mucosa, the alveolar mucosa and the lower mucobuccal fold on the chewing side (p < 0.001). There was no significant association between the occurrence of the white lesions and smoking. Even though the majority of the white lesions (85.4%) were homogenous, 71.4% of the non homogenous lesions were identified in khat chewers. Vital staining with toluidine blue and exfoliative cytology was conducted on a subset of patients with homogenous and non-homogenous oral lesions, and there were no findings suspicious for pre-malignant or malignant changes.

Discussion

This study demonstrated a relationship between khat chewing and oral white lesions, which we attribute to chronic local mechanical and chemical irritation of the mucosa. Our findings also suggest that mucosal changes associated with khat are benign, however, this initial study requires further studies including follow-up of khat users to confirm the current findings, including the likely benign changes associated with chronic use and histologic findings of clinical lesions.

Effect of Catha edulis (khat) chewing on plasma lipid peroxidation

The effect of regular khat (Catha edulis) chewing and the combination of khat chewing and smoking on plasma lipid peroxidation as a biomarker of oxidative stress and free radical activity (measured as plasma malondialdehyde, MDA), as well as on the lipid profiles were investigated. The fasting plasma levels of MDA were non-significantly higher in both groups (4% in khat chewers and 9.2% in khat chewers and smokers), whereas these levels were observed to be significantly increased at post meal and 2h through the khat session. Post meal increase of plasma MDA could be attributed partially to the meal-induced oxidative stress and the possible decrease in the overall antioxidant capacity. This increase in plasma levels of MDA in both tested groups were found to be higher in the control group suggesting the presence of other contributing factors beside the meal-induced oxidative stress. Plasma levels of MDA were observed to fall slightly 2h through the khat session over the post meal levels, suggesting a lack of additive effect of khat consumption. Plasma triglycerides, total cholesterol, and LDL-cholesterol were shown to be non-significantly affected in this study by khat chewing or by the combination of khat chewing and smoking.

Pharmacokinetics of cathinone, cathine and norephedrine after the chewing of khat leaves

AIM

The stimulating herbal drug khat is habitually used in East Africa and the Arabian peninsula but is also imported into other countries. The aim was to study the pharmacokinetics of its alkaloids cathinone, cathine and norephedrine.

METHODS

Four volunteers chewed khat leaves in an amount equivalent to one-quarter of that used in a typical khat session. Blood samples were collected up to 80 h and the alkaloids were assayed using gas chromatography-mass spectrometry. The data were evaluated using computerized pharmacokinetic compartmental analysis.

RESULTS

The plasma concentration-time data for the alkaloids could be described using a two-compartment model with two-segment absorption. The mucosa of the oral cavity is considered to be the first absorption segment, where the major proportion of the alkaloids is absorbed (mean +/- SD 59 +/- 21% for cathinone and 84 +/- 6% for cathine). The extraction of the alkaloids from the leaves by chewing was very effective with only 9.1 +/- 4.2% remaining as a residue. Cathinone was eliminated from the central compartment with a mean half-life of 1.5 +/- 0.8 h. The half-life of cathine was 5.2 +/- 3.4 h. The metabolism of cathinone to norephedrine had a substantial influence on its plasma concentration profile. Psychophysical functions were essentially unaffected by the chewing of khat.

CONCLUSIONS

The pharmacokinetics of khat alkaloids in humans explain why chewing is the preferred form of khat ingestion. Subjects absorbed a mean dose of 45 mg of cathinone, and did not suffer any severe adverse reactions.

The effect of khat chewing on gallbladder motility in a group of volunteers

An increase in the prevalence of gallstones has been reported from the Middle East and the Republic of Yemen. Changing dietary habits and obesity are thought to be responsible but other local factors may contribute such as chewing the leaves of the khat plant (Catha edulis Forsk.) which is a widespread social custom in Yemen. We have studied the effects of khat chewing on gallbladder motility in a group of 10 healthy volunteers. All subjects underwent ultrasound measurements of gallbladder volume after chewing khat leaves or lettuce, which was used as the control. Results were compared after chewing for up to 2h in the fasting state and in response to a fatty meal. There was no significant change in gallbladder volume after chewing khat compared with lettuce in the fasting state (P=0.7) or in gallbladder emptying after a fatty meal (P=0.4) and we conclude that khat chewing has no clinically significant effect on gallbladder motility.

Khat: pharmacological and medical aspects and its social use in Yemen

Fresh leaves of the khat tree (Catha edulis Forsk.) are chewed for their euphoric properties in East Africa and parts of the Middle East, such as The Yemen. This review describes the history, cultivation and constituents of khat, and the social aspects of khat chewing in Yemen. The major pharmacologically active constituent of the fresh leaves is (--)-S-cathinone. The pharmacology of (--)-S-cathinone in the central nervous system and the peripheral effects are described. (--)-S-Cathinone is regarded as an amphetamine-like sympathomimetic amine and this mechanism of action is discussed in relation to the central stimulant actions and the cardiovascular effects of increasing blood pressure and heart rate. The risk factors associated with khat chewing are described, with emphasis on the reported increased incidence of acute myocardial infarction.

The effect of Qat chewing on blood pressure and heart rate in healthy volunteers

The leaves of the Qat plant (Catha edulis Forsk., Celastraceae) which contain amphetamine like compounds are widely chewed in Yemen and East Africa for their pleasurable stimulant properties. There are also a number of unwanted side-effects and this paper studies the effect on heart rate and blood pressure in 80 healthy volunteers. During a 3-h period of chewing fresh Qat leaves there was a significant and progressive rise in systolic and diastolic blood pressure and heart rate, and levels had not returned to baseline 1 h after chewing had ceased. Further studies are needed on possible cardiovascular morbidity associated with regular Qat chewing.

Determination of (S)(-)-cathinone by spectrophotometric detection

Previous studies on the Khat plant (Catha edulis, Celastraceae) illustrated the importance of using freshly harvested young shoots and leaves such that cathinone, the principle active component and Schedule I controlled drug contained within the plant, could be suitably isolated and identified. The purpose of this work was to develop a quantitative analytical technique for the determination of cathinone. The proposed method is based on treating the reductant cathinone with copper(II)-neocuproine reagent in sodium acetate-buffered medium followed by measuring the absorbance of the copper(I)-neocuproine complex at 455 nm. The calibration plot is linear in the range 0.08-25 micrograms ml-1 with a detection limit of 0.08 microgram ml-1. The precision of the method, expressed as the relative standard deviation, is 1.35% for 10 micrograms ml-1 cathinone. Good recoveries have been obtained in applying the method to the analysis of cathinone in Khat leaves.