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

Distinct single cell signal transduction signatures in leukocyte subsets stimulated with khat extract, amphetamine-like cathinone, cathine or norephedrine

Background

Amphetamine and amphetamine derivatives are suggested to induce an immunosuppressive effect. However, knowledge of how amphetamines modulate intracellular signaling pathways in cells of the immune system is limited. We have studied phosphorylation of signal transduction proteins (Akt, CREB, ERK1/2, NF-κB, c-Cbl, STAT1/3/5/6) and stress sensors (p38 MAPK, p53) in human leukocyte subsets following in vitro treatment with the natural amphetamine cathinone, the cathinone derivatives cathine and norephedrine, in comparison with a defined extract of the psychostimulating herb khat (Catha edulis Forsk.). Intracellular protein modifications in single cells were studied using immunostaining and flow cytometry, cell viability was determined by Annexin V-FITC/Propidium Iodide staining, and T-lymphocyte proliferation was measured by ³H-thymidine incorporation.

Results

Cathinone, cathine and norephedrine generally reduced post-translational modifications of intracellular signal transducers in T-lymphocytes, B-lymphocytes, natural killer cells and monocytes, most prominently affecting c-Cbl (pTyr700), ERK1/2 (p-Thr202/p-Tyr204), p38 MAPK (p-Thr180/p-Tyr182) and p53 (both total p53 protein and p-Ser15). In contrast, the botanical khat-extract induced protein phosphorylation of STAT1 (p-Tyr701), STAT6 (p-Tyr641), c-Cbl (pTyr700), ERK1/2 (p-Thr202/p-Tyr204), NF-κB (p-Ser529), Akt (p-Ser473), p38 MAPK (p-Thr180/p-Tyr182), p53 (Ser15) as well as total p53 protein. Cathinone, cathine and norephedrine resulted in unique signaling profiles, with B-lymphocytes and natural killer cells more responsive compared to T-lymphocytes and monocytes. Treatment with norephedrine resulted in significantly increased T-lymphocyte proliferation, whereas khat-extract reduced proliferation and induced cell death.

Conclusions

Single-cell signal transduction analyses of leukocytes distinctively discriminated between stimulation with cathinone and the structurally similar derivatives cathine and norephedrine. Cathinone, cathine and norephedrine reduced phosphorylation of c-Cbl, ERK1/2, p38 MAPK and p53(Ser15), and norephedrine induced T-lymphocyte proliferation. Khat-extract induced protein phosphorylation of signal transducers, p38 MAPK and p53, followed by reduced cell proliferation and cell death. This study suggests that protein modification-specific single-cell analysis of immune cells could unravel pharmacologic effects of amphetamines and amphetamine-like agents, and further could represent a valuable tool in elucidation of mechanism(s) of action of complex botanical extracts.

Khat: social habit or cultural burden? A survey and review

The aim of this article was to investigate the psychological and socioeconomic ramifications of Khat on its users and their communities. A thorough literature review was undertaken and a questionnaire was distributed among a Somali community in South London. From the 62 individuals surveyed, 79% were born in Somalia and 15% in the United Kingdom. Participants were asked to answer specific questions about their Khat use, their attitudes toward Khat use, and its perceived effect on their communities. The harms of Khat use are numerous, although they are not well recognized by its users. Khat's legal status means that it is widely available. Measures to reconsider its legality should be considered given the harm on its users.

Gender differences in patterns and correlates of khat and tobacco use

INTRODUCTION

Although research suggests gender differences in patterns of tobacco use, whether gender moderates concurrent use of tobacco and other substances remains unclear. In some parts of Africa and the Middle East, tobacco is often accompanied with khat (Catha edulis), a widely used substance in these regions. The concurrent use of tobacco and khat may represent a public health burden spreading to other countries in Europe and North America.

METHOD

A total of 189 participants (69 women) khat users and smokers in Yemen were asked to complete questionnaires that focused on patterns of khat and tobacco use. Chi-square tests, analyses of variance, and correlational analyses were conducted.

RESULTS

Reported frequency and intensity of khat and tobacco use were greater among men than in women. Also, reported number of cigarettes smoked during a khat session was higher among men than among women, whereas frequency of waterpipe use during the session was greater among women than among men. Smoking status (daily or occasional) was positively associated with khat use in women only. Age of onset of khat use was inversely related to the number of cigarettes smoked during a khat session and with intensity of khat chewing. The majority of participants reported that they had thought about and have attempted to quit khat and tobacco use.

CONCLUSIONS

The results provide evidence for gender differences in patterns of concurrent use of tobacco and khat. Identifying determinants of tobacco and khat use may be useful in reducing the risk of their negative health outcomes.

Functional evaluation of the receptors mediating vasoconstriction of rat aorta by trace amines and amphetamines

Trace amines including β-phenylethylamine (β-PEA) and amphetamines classically exert pharmacological actions via indirect sympathomimetic mechanisms. However, there is evidence for other mechanisms and this study explores the receptors mediating vasoconstriction in rat aorta. β-PEA, d-amphetamine, MDMA, cathinone and methylphenidate caused concentration-dependent contractions of rat isolated aortic rings which were unaffected by prazosin (1 μM), ICI-118,551 (1 μM), cocaine (10 μM) and pargyline (10 μM), to inhibit α1- and β2-adrenoceptors, neuronal transport and monoamine oxidase (MAO), respectively. Octopamine concentration-response curves, however, were shifted to the right. In the presence of the inhibitors, the rate of onset of octopamine contractions was slowed. Lineweaver-Burk analysis of the kinetics of the response generated different KM values for octopamine in the absence (2.35 × 10(-6)M) and presence (6.09 × 10(-5)M) of inhibitors, indicating mediation by different receptors. Tryptamine-induced vasoconstriction also resisted blockade by adrenergic inhibitors and the 5-HT1A, 1B, 1D and 5-HT2A receptor antagonists, methiothepin (50 nM) and ketanserin (30 nM), respectively. Trace amines and amphetamines therefore exert vasoconstriction independently of adrenoceptors, neuronal transport and 5-HT receptor activation. There was no evidence of tachyphylaxis or cross-tachyphylaxis of the vasoconstriction to these amines. Tyramine was a partial agonist and in its presence, β-PEA, d-amphetamine and octopamine were antagonised indicating that they all act through a common receptor for which tyramine serves as an antagonist. We conclude that the vasoconstriction is via TAAR-1, because of structural similarities between amines, ability to stimulate recombinant trace amine-associated receptor 1 (TAAR-1) and the presence of TAAR-1 in rat aorta.

Direct analysis in real time mass spectrometry (DART-MS) of "bath salt" cathinone drug mixtures

Rapid and versatile direct analysis in real time mass spectrometry (DART-MS) methods were developed for detection and characterization of synthetic cathinone designer drugs, also known as "bath salts". The speed and efficiency associated with DART-MS testing of such highly unpredictable samples demonstrate the technique as an attractive alternative to conventional GC-MS and LC-MS methods. A series of isobaric and closely related synthetic cathinones, alone and in mixtures, were differentiated using high mass accuracy and in-source collision induced dissociation (CID). Crime laboratories have observed a dramatic rise in the use of these substances, which has caused sample testing backlogs, particularly since the myriad of structurally related compounds are challenging to efficiently differentiate. This challenge is compounded by the perpetual emergence of new structural variants as soon as older generation derivatives become scheduled. Because of the numerous chemical substances that fall into these categories, along with the varying composition and complexity of mixtures of these drugs, DART-MS CID has the potential to dramatically streamline sample analysis, minimize the number of sample preparation steps, and enable rapid characterization of emerging structural analogs.

Khat dependence syndrome: a cross sectional preliminary evaluation amongst UK-resident Yemeni khat chewers

ETHNOPHARMACOLOGICAL RELEVANCE

Khat is a natural psychostimulant that has pharmacological effects similar to that of amphetamine. The behaviour of khat chewing is embedded within a cultural context. Meanwhile khat chewing is associated with psychological and physiologically burden, as a 'dependence producing' substance.

AIMS OF THE STUDY

To assess the applicability of the construct of substance dependence syndrome (DSM-IV, 1994) to khat chewing and to examine psychosocial and behavioural correlates of this syndrome including tobacco use.

MATERIALS AND METHODS

A sample of 204 khat chewers was recruited during random visits to khat sale outlets. A face to face interview that assessed socio-demographic, psychosocial dependence, substance dependence syndrome and behavioural characteristics was conducted. Descriptive, exploratory psychometric and multivariate analyses were employed.

RESULTS

Approximately a third (31%) of khat chewers reported symptoms consistent with dependence syndrome including increased khat chewing (13%) and cessation attempts (19%) while 17% reported withdrawal symptoms including depression (61%), increase in appetite (74%) and interrupted sleep (58%). Thirty-eight percent reported continued khat chewing despite impacts on their health. Psychometric assessment of the DSM-IV criteria for khat chewing dependence identified two factors; factor 1 consisted of bio-behavioural items and factor 2 withdrawal items, accounting for 67% of the variance and Cronbach's alpha coefficient at 0.78. In multivariate logistic regression modelling, there was an association between intensity of psychological khat dependence (SDS-Khat) and nicotine dependence with the likelihood of exhibiting khat chewing dependence syndrome (p=0.0005, OR=1.51, 95%CI=1.33-1.71; p=0.043, OR=2.87, 95%CI=1.03-7.98, respectively).

CONCLUSIONS

The substance dependence syndrome criteria are applicable to khat chewing and associated with increased intensity of nicotine and psychological khat dependence. The applicability of khat dependence syndrome and exploration of its dimensions and associated factors should be extended in future research. Concurrent validation of these findings using specific objective measures for self-report khat chewing is also recommended.

A case of treating cathinone dependence and comorbid depression using bupropion

Cathinone is a potent CNS stimulant found in khat leaves. Cathinone and synthetic cathinone-derivatives have become popular recreational drugs in recent years, commonly marketed as "legal highs." In addition to acute physical and psychiatric adverse effects, dependence on these substances is a concern. The following case reports describes a young man with cathinone dependence and depression that was treated using bupropion. Bupropion is a cathinone-derivative with a dual dopamine-norepinephrine reuptake inhibiting mechanism, which is approved for the treatment of depression and smoking cessation. Clinical awareness to the addictive potential of cathinone and cathinone-derivatives is important. Research regarding the potential effectiveness of bupropion in these cases is needed.

Qat chewing as an independent risk factor for periodontitis: a cross-sectional study

This study assessed the effect of qat chewing on periodontal health, independent of other risk factors. Four hundred qat chewers and 100 nonchewers (20–50 years) were included. Demographic data and detailed information about chewing and smoking were obtained. Periodontal status was assessed using Community Periodontal Index (CPI) and clinical attachment loss (CAL). The qat chewers were older, included more males and smokers, and had worse oral hygiene but higher education levels; the majority were heavy chewers (mean duration of 14.45 years and frequency of 6.10 days/week). Regression analysis identified age, oral hygiene, education level, and cigarette smoking as independent predictors of periodontal destruction. Adjusted for these, qat chewing showed marginally significant association only with CAL (OR = 4.7; P = 0.049). The chewing sides showed significantly higher scores than the nonchewing sides; however, equal scores on both sides or lower scores on the chewing sides (possibly no or beneficial effect) were still observed in 50% of the chewers. Heavy qat chewing is shown here as an independent risk factor for attachment loss. However, the possibility that the habit may have beneficial effects in a subset of the chewers cannot be excluded. A holistic model that resolves the existing contradiction is presented.

Association of Khat and alcohol use with HIV infection and age at first sexual initiation among youths visiting HIV testing and counseling centers in Gamo-Gofa Zone, South West Ethiopia

Background

HIV/AIDS is the major problem and an obstacle to both the health and development of people in Ethiopia today. It is also indicated that the use of substances have dramatically increased despite the serious concern about HIV infection.

Methods

Unmatched case control study was conducted in South West Ethiopia using a sample of 105 cases and 305 controls. Multivariate logistic regression was used to assess the degree of association between dependent and independent variables.

Result

HIV infection was positively associated with being in the age of 20 – 24 years [OR & (95% CI) = 2.892 (1.266, 6.607)], being female [OR & (95% CI) = 2.013 (1.061, 3.822)], alcohol use [OR & (95% CI) = 5.883 (3.034, 11.408)], having no education [OR & (95% CI) = 3.193 (1.523, 6.695)] and primary education level [OR & (95% CI) = 3.160 (1.351, 7.388)]. Early sexual initiation was also positively associated with being not employed Adj. HR & (95% CI) = 7.372 (1.455, 37.357)], not having comprehensive knowledge on HIV/AIDS [Adj. HR & (95% CI) = 8.247 (2.121, 32.067)], alcohol use [Adj. HR & (95% CI) = 3.815 (1.315, 11.070)] and khat use [Adj. HR & (95% CI) = 7.241 (1.871, 28.016)].

Conclusion

Strategies should be designed to control the use of alcohol and khat which were found to be predictors of HIV infection and early sexual initiation in this study.

A nested case-control study on relapse predictors among tuberculosis patients treated in Yemen's NTCP

SETTING

The National Tuberculosis (TB) Control Programme in Yemen.

OBJECTIVE

To identify risk factors associated with TB relapse.

METHODS

In a prospective nested case-control study, relapse cases were recruited from a cohort of pulmonary TB patients registered between July 2007 and June 2008. Four controls per case were randomly selected from the list of non-relapse patients. Three forms were used for data collection, which included interviews with the participants and review of their medical cards and TB registers. Multivariate logistic regression analysis was performed to identify independent risk factors for relapse.

RESULTS

A relapse rate of 5.7% was found. Multivariate logistic regression analysis showed that unemployment, smoking, presence of cavitations, weight gain, weight loss, non-adherence during the continuation phase and diabetes were significantly associated with relapse (P < 0.05).

CONCLUSION

Relapse rates can be reduced by ensuring that patients take their treatment regularly and are counselled effectively to stop smoking. Reinforcing the implementation of the DOTS strategy and strengthening the anti-smoking campaigns are important actions. Action to help unemployed patients, including free services and the creation of new job opportunities, should be adopted. Using rifampicin-based regimens in the treatment of cavitary TB and bi-directional screening in TB and diabetes patients are recommended.

Khat use among HIV voluntary counselling and testing centre clients in Ethiopia

Khat (Catha edulis, a natural stimulant), has been used in Ethiopia for centuries. Over the past few decades, however, its use has dramatically increased, with recent research linking khat use to HIV status. Using qualitative methods, we explored the individual and micro-environmental characteristics of khat use and the social and physical contexts influencing type, acceptability and consequences of khat use. Among khat chewers attending an HIV voluntary counselling and testing centre in Addis Ababa, Ethiopia, we found that chewing typically starts at an early age (15-18 years). The majority of users are young (aged 18-35) and chew for pleasure, primarily in social settings. Over 25 types of khat, with varying effects were reported. Approximately half of the participants perceived khat to enhance sexual desire, while the rest claimed the effect on sexual desire to be the opposite. Alcohol use among chewers was high. Our findings suggest the need for culturally appropriate interventions that highlight the factors associated with khat use and the potential interplay between khat, alcohol and risky sexual behaviour.

Prevalence and determinants of khat (Catha edulis) chewing among high school students in eastern Ethiopia: a cross-sectional study

BACKGROUND

Use of psychoactive drugs such as khat leaves (Catha edulis) alter moods and emotional state and lead to adverse effects on the health and social life of users. Ethiopia is a major producer and exporter of khat in east Africa and the majority of the khat comes from the eastern part of the country, however, no studies have been conducted to investigate the habit in this area. This study was conducted to assess the prevalence and predictors of khat chewing among high school students in Harar, eastern Ethiopia.

METHODOLOGY

The study was conducted among 1,890 secondary school students in Harar town in April 2010. A structured self-administered questionnaire was used for data collection. Descriptive statistics and logistic regression were performed to examine the prevalence and predictors of khat chewing.

RESULT

The overall prevalence of khat chewing among the sample was 24.2% (95% CI 22.2%-26.2%). About 28.5% of females and 71.5% of males had chewed khat. Older age (OR 1.31; 95% CI 1.16-1.49), male gender (OR 2.10; 95% CI 1.50-2.93), Muslim religion (OR 1.88; 95% CI 1.17-3.04), having friends who chewed khat (OR 7.93; 95% CI 5.40-11.64), and availability of someone with a similar habit in the family (OR 1.50; 95% CI 1.07-2.11) were found to be independent predictors of chewing.

CONCLUSION

A significant proportion of students chew khat. The use of khat is significantly associated with age, gender, Muslim religion, peer influence and habit of family and other relatives among students. Measures such as educational campaigns need to be instituted to create awareness among school adolescents and their parents in order to reduce the prevalence of the habit and its adverse social and health consequences.

Acute exposure to Catha edulis depresses contractility and induces myocardial infarction in spontaneously contracting, isolated rabbit's heart

Khat chewing is a recreational habit known to pose major socio-economic and medical problems in countries of Southern Arabia and the Horn of Africa. Among other adverse health effects, khat chewing has been associated with an increased risk of myocardial infarction (MI) in heavy consumers. This study was carried out to examine the direct effects of Catha edulis extract on contractility of spontaneously contracting, isolated rabbit heart and to investigate its mechanism of action. Isolated six rabbit's hearts attached to a Langendorff apparatus were perfused with extract at a constant flow rate and continuously bubbled with a 95% O2/5% CO2 gas mixture. Each heart served as its own control, as responses were recorded before and after administration of C. edulis extract. Varying concentrations of extract (50, 100 and 250 mg/ml) were loaded in the perfusate, their effects recorded and effluent fluid collected for assay of cardiac enzymes. Histological examination of the cardiac tissue was performed at the end of perfusion with 250 mg/ml extract. This study revealed that acute exposure to C. edulis extract exerted negative inotropic and chronotropic effects on isolated hearts. The extract also had a vasoconstrictor effect on coronary vessels, independent of α1 adrenergic receptor stimulation. Histological examination of hearts perfused with 250 mg/ml C. edulis extract revealed the presence of histological changes unique to myocardial infarction, a finding consistent with observed increased levels of cardiac enzymes in perfusates. Thus, we have demonstrated experimentally a direct cardiac depressant- and MI inducing effects of C. edulis extract. These results are consistent with the earlier reported deleterious effects of khat on cardiovascular function among khat chewers.

Qat consumption in Yemen – knowledge and practice of mental health policy makers and other stakeholders

Purpose

This paper seeks to report the findings of a half‐day workshop on the impact and control of Qat, held in Yemen in February 2010. Senior mental health policy makers, professionals and leaders of mental health non‐governmental organizations (NGOs), were present as part of a wider five‐day national stakeholder conference to develop national mental health strategy for Yemen, at the request of the Social Development Fund for Yemen and in collaboration with the Ministry of Health. The purpose of the half‐day workshop was to examine the knowledge and practice of senior Yemeni mental health policy makers and other stakeholders in relation to Qat.

Design/methodology/approach

The stakeholders were purposively selected by the Yemen Social Development Fund to provide representation from the Ministry of Health, the Ministry of Social Affairs, Ministry of Human Rights, Ministry of Religious Affairs and Department of Prison Administration, which is linked to the Ministry of the Interior, United Nations Childrens Fund, various mental health NGOs and psychiatrists and psychologists from the main universities in the country. The stakeholders were divided into four workgroups, and each group was given a specified theme to discuss for an hour, namely the impact of Qat on the Yemen economy, health and society and measures to control the use of Qat. All participants were also asked if they habitually chewed Qat.

Findings

The stakeholders (professionals, policy makers and leaders of NGOs) were very knowledgeable about the physical, psychological and social effects of habitual Qat consumption, and yet all except one were habitual chewers.

Originality/value

Efforts to discourage the chronic use of Qat will need to be strenuous, consistent and coordinated across sectors. Knowledge of health and social risks alone is unlikely be sufficient to bring about change.

Psychoses, PTSD, and depression in Somali refugees in Minnesota

INTRODUCTION

Initial clinical observation of Somali patients seen at a busy inner-city community clinic (CUHCC) suggested that, in addition to the expected pictures of Posttraumatic Stress Disorder (PTSD) and depression previously seen in the clinic's Southeast Asian refugee population from 1980 to 2000, there was an unusually high number of young Somali men presenting with acute psychotic disturbances.

OBJECTIVES

The aim of this study of health care utilization of Somali refugees (N = 600) seen in the mental health unit of the clinic from 2001 to 2009 was to investigate the major patterns of psychiatric disorders in this outpatient population and compare these findings with a cohort of non-Somali patients (N = 3,009) seen at the same outpatient clinic during the years 2007-2009. If the results supported the initial clinical observations that the rate of psychoses was higher among young Somali men than non-Somali men attending CUHCC clinic, then several areas of further research would recommend itself. First, since this study was not a study of prevalence of mental illness in the Somali community, the next step would be to undertake a study of community prevalence of mental illness among different age and gender cohorts. Second, further research should look into likely causative and contributory risk factors to explain the development of psychoses among Somali young men.

METHODS

Somali and non-Somali patients were diagnosed according to DSM-IV-R criteria. Main outcome measures (diagnoses, age cohort, sex) were analyzed by Chi-square tests. Patterns of illness and adjustment varied significantly by age and gender cohorts, reflecting the relevance of age and gender at time of trauma on different trauma and loss experiences and cultural and religious shaping of subsequent adjustment and symptoms.

RESULTS

The study confirmed that almost half of the Somali male patients are under age 30, 80% of whom presented with psychoses, compared with the rate of psychosis (13.7%) in the non-Somali control group of same-aged males at the clinic. The older male, and the majority of Somali female patients, show predominantly depressive and PTSD symptomatology.

CONCLUSIONS

War trauma experienced in childhood, early malnutrition from famines, head trauma, and excess Khat use in male adolescents provide partial explanations for the large number of young psychotic Somali men seen in the clinic from 2001 to 2009.

Khat Use and Trait Anger: Effects on Affect Regulation during an Acute Stressful Challenge

Khat (Catha edulis) is a widely used stimulating drug often consumed in daily routine in Yemen and East African countries. Chewing khat acutely elicits states of euphoria and feelings of well-being which later shift into emotional instability and low mood. Little is known about emotional regulation in habitual khat chewers. In this study, we compared self-reports on trait anger as well as positive and negative affect responses to a mental arithmetic challenge. Participants included 135 men and women from Yemen who chew khat regularly, occasionally or not at all. Participants attended a laboratory session that involved resting periods and performing a math challenge. Analyses of variance and regression show that regular khat chewing is associated with higher trait anger, more pronounced negative responses during stress and less pronounced positive emotional states. These results suggest that regular khat chewing is associated with disturbances in emotion regulation processes.

A good chew or good riddance--how to move forward in the regulation of khat consumption

AIMS

To review the status of khat, the most recent plant based psychoactive substance to reach a global market, and consider policy making processes in general and the framework of drug control in particular.

MATERIALS AND METHODS

Desk review of literature on khat and wider drug policy processes.

RESULTS

The risk assessment and classification of psychoactive drugs is a contested arena where political, economic and moral agendas collide, leaving countries that have banned khat, with significant social costs. To best manage the risks arising from the increasing availability of khat it is therefore suggested to draft a regulatory framework with clear objectives and guiding principles.

CONCLUSIONS

Given that medical risks of khat use are modest, the objective of the regulatory framework should be the protection of consumers and community. This is best achieved by establishing processes for the quality control of khat imports, and by regulating access and availability. It should therefore not be considered as a drug to be controlled but as a licit substance that needs to be regulated.

The stimulant khat--another door in the wall? A call for overcoming the barriers

AIM

In this article, we comment on the current international discourse on khat, we highlight pitfalls and and suggest balanced national international regulatory actions.

METHOD

A brief an focussed review of the available literature on khat and health and examples from our own research are provided.

RESULTS

The use patterns of catha edulis (khat) have changed throughout the last decades. During this period khat has had a remarkable economic boom and developed from a niche crop to the backbone of the regional economy. Now it contributes to the livelihoods of millions of people. Today, khat use is often the proverbial "Door in the wall" for large parts of the populations in African and Arab countries beyond the traditional user groups. Its use is often excessive and not restricted by social regulation mechanisms. Under such conditions, problematic khat use patterns develop rapidly, exemplified by the growing group of binge users, and it gets even prevalent among especially vulnerable groups such as children, people with mental disorders or pregnant women. The currently existing scientific evidence suggests that problematic use patterns not the use per se can be linked to numerous health consequences.

CONCLUSION

This paper argues that changed patterns of khat use are a burden for some of the most underdeveloped countries in the world. But the debate around khat is stuck between extreme poles arguing for prohibition or for de-regulation. Here, we call for a balanced action of governments and international organizations leaving behind the decades of debilitating debate pro vs. contra scheduling and banning khat leaves. Instead, regulation and harm-reduction measures are urgently needed. We suggest a number of steps that should be taken immediately to better understand current khat use patterns, to address noxious excesses and to relieve suffering.

Validity and reliability of a Severity of Dependence Scale for khat (SDS-khat)

AIMS OF THE STUDY

(1) To assess psychological khat dependence and (2) to assess the validity and reliability of the Severity Dependence Scale (Gossop et al., 1995) amended for khat use (SDS-khat), in a sample of UK-resident male adult Yemeni khat chewers.

MATERIALS AND METHODS

A cross-sectional study using a face to face structured interview schedule was conducted amongst purposively sampled UK-resident adult Yemeni male khat chewers, aged 18 years and above, selected during random visits to places of khat sale. A factor analysis with principal components extraction was conducted to explore the construct validity of the proposed SDS-khat. Reliability of the proposed scale was assessed using test-retest and internal reliability tests. The concurrent validity of the proposed SDS-khat was assessed in relation to individual measures and a composite index of khat chewing behaviours using univariate analyses.

RESULTS

Two hundred and four Yemeni male adult khat chewers were interviewed. The mean score of the proposed SDS-khat was 5.52 (SD ±4.03). Forty nine percent of respondents (95% CI=43-55%) with ≤5 scores were more likely not psychologically dependent. A single factor, uni-dimensional solution identifying the five items making up the scale accounted for 52.33% of variance. The internal reliability was good (Cronbach's alpha coefficient=0.76) and the test retest intraclass correlation coefficient (ICC) was 0.93 (95% CI=0.80-0.97). Many individual aspects of the khat chewing were significantly related to the scale. Assessment of the proposed SDS-khat's concurrent validity with individual items of khat chewing identified several significant relationships (p≤0.05) whilst the composite index of khat behaviour also identified a significant relationship (OR=14.40, 95% CI=6.71-30.89). The proposed SDS-khat also correlated with self-reported reasons for khat chewing (p≤0.001, OR=3.54; 95% CI=1.80-6.96).

CONCLUSIONS

In this sample of Yemeni khat chewers the SDS-khat is recommended as a valid and reliable research tool for measuring psychological dependence upon khat. Further validation in other samples is indicated.

Khat use and neurobehavioral functions: suggestions for future studies

Although there is a rich body of research available regarding the effect of acute and chronic khat dosing in animal models, research on the behavioral and cognitive effects of khat in human subjects is not extensive and several of the available studies have been done only in the context of observational and single-case studies. In light of the absence of a substantial literature on the neurobehavioral deficits associated with khat use and to provide a context that could be used to identify themes for future research we review previous research that has focused on other stimulant drugs. This review highlights multiple areas of neurocognitive deficit that have been identified in previous studies of individuals who have been chronic users of stimulants, such as amphetamines and methamphetamines. The review highlights a substantial body of evidence demonstrating a wide range of learning and memory impairments including deficits that persist during abstinence from active drug use. This review does not imply a similar khat effect, but due to some similarities pharmacologically between the active components of khat (cathinone and cathine) and amphetamines, future studies examining these same domains of cognitive functioning in chronic khat users and abstinent khat users appears to be warranted, if possible using some of the same or similar laboratory measures.

Concentration levels of essential and non-essential metals in Ethiopian khat (Catha edulis Forsk)

The levels of essential (Ca, Mg, Mn, Fe, Zn, Cr, Cu, and Co) and non-essential (Cd and Pb) metal in six different varieties of Ethiopian khat (Catha edulis Forsk, an evergreen stimulant plant) commonly consumed in the country and exported to the neighboring countries were determined by flame atomic absorption spectrometry. Known weight of oven-dried khat samples were wet-digested using 2 mL of (69-72%) HNO(3) and 2 mL of (70%) HClO(4) for 2 h and 30 min at variable temperature (120-270°C). The mineral contents in the digests were analyzed using flame atomic absorption spectrometer. The following concentrations ranges in fresh-weight basis were recorded in decreasing order: Ca (1,038-2,173 µg/g) > Mg (478.2-812.3 µg/g) > Fe (53.95-82.83 µg/g) >Zn (5.18-9.40 µg/g) >Mn (6.98-8.66 µg/g) >Cu (1.85-5.53 µg/g) > Cr (0.66-3.47 µg/g) >Co (0.41-0.80 µg/g). A wide variation in the mineral contents of khat from different region of Ethiopia was noticed. The toxic metals (Pb and Cd) were not detected in all the samples analyzed.

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.

Motives for khat use and abstinence in Yemen--a gender perspective

Background

Khat consumption is widespread in Yemeni society and causes problems both in economic development and public health. Preventive measures have been largely unsuccessful and the cultivation continues to proliferate. The gender-specific motives for khat use and abstinence were studied to create a toe-hold for more specific interventions.

Methods

In a quota sample with equal numbers of males, females, abstainers and consumers, 320 subjects were interviewed on their specific opinions about khat and its impact on subjective and public health, and on social and community functioning. Strata were compared in their acceptance and denial of opinions. Notions that could predict abstinence status or gender were identified with multivariate logistic regression analysis.

Results

Male khat users had a strong identification with khat use, while females were more ambivalent. The notion that khat consumption is a bad habit (odds ratio (OR) 3.4; p < 0.001) and consumers are malnuorished (OR 2.2; p = 0.046) were associated with female gender among khat users. Among the females worries about health impact (OR 3.2; p = 0.040) and loss of esteem in the family (OR 3.1; p = 0.048) when using khat predicted abstinence. Male abstainers opposed khat users in the belief that khat is the cause of social problems (OR 5.1, p < 0.001). Logistic regression reached an accuracy of 75 and 73% for the prediction of abstinence and 71% for gender among consumers. (All models p < 0.001.)

Conclusions

Distinct beliefs allow a differentiation between males, females, khat users and abstainers when targeting preventive measures. In accordance to their specific values female khat users are most ambivalent towards their habit. Positive opinions scored lower than expected in the consumers. This finding creates a strong toe-hold for gender-specific public health interventions.

Oral manifestations of habitual khat chewing: a case-control study

BACKGROUND AND OBJECTIVES

Khat, or qat (Catha edulis), is a shrub indigenous to Yemen and certain parts of eastern Africa. Chewing the leaves, which have sympathomimetic and euphoric effects, is a popular habit in numerous countries including the Yemenite population in Israel. Khat has potentially significant toxic effects; however, its oral effects have been only sporadically examined and some changes suggested. The aim of this study was to assess the association between habitual Khat use and oral/dental pigmentation, gingival health, and reports of oral dryness.

STUDY DESIGN

Forty-seven Yemenite Israeli individuals >30 years old, who chewed Khat at least twice a week for over 3 years, and 55 control subjects were studied. All individuals underwent standard clinical oral examinations for color changes and gingival health.

RESULTS

White changes were significantly more prevalent in the khat chewers, identified primarily at the chewing site (83% vs. 16%). The difference in the prevalence of oral mucosal pigmentation between nonchewing nonsmoking (66.7%) and the khat-chewing (100%) groups was highly significant. The mean gingival index and the depth of periodontal pockets of the khat-chewing subjects were significantly reduced at the chewing side compared with the nonchewing side. Increased gingival recession was recorded on the khat-chewing side. Discoloration of the teeth adjacent to the site of chewing was recorded. Oral dryness occurring 30 minutes after initiating the khat-chewing session was reported by khat users.

CONCLUSION

Khat chewing may result in a number of changes in the oral mucosa and the dentition. The mechanical and chemical irritation may result in the development of mucosal white lesions and dark pigmentation. Khat chewing may reduce aspects related to risk of gingival and periodontal inflammation, but it appears to be associated with attachment loss at the site of chewing.

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).

Regular Khat (Catha edulis) chewing is associated with elevated diastolic blood pressure among adults in Butajira, Ethiopia: a comparative study

BACKGROUND

Fresh leaves and buds of the Khat plant (Catha edulis) contain Cathinone, an amphetamine like alkaloid responsible for its pharmacological action. Chewing of Khat has been associated with a transient rise in blood pressure and heart rate in experimental studies. Few studies examined the effect of regular or frequent Khat chewing on blood pressure at the population level. This study was conducted to examine the association of regular Khat chewing with blood pressure among adults.

METHODS

We compared systolic and diastolic blood pressure of adults 35-65 years of age who reported regular chewing of Khat during the preceding five years to those who never chewed Khat during the same period. Study participants were recruited from purposively selected urban and rural villages of Butajira District in Ethiopia. The comparative groups, chewers (334) and non-chewers (330), were identified from among the general population through a house-to-house visit using a screening questionnaire. They were frequency-matched for sex and age within a five-year range. Data were collected through structured interviews and physical measurements including blood pressure, weight and height.

RESULTS

The prevalence of hypertension was significantly higher among Khat chewers (13.4%) than non-chewers (10.7%), odds ratio (OR) = 1.66 (95% confidence interval (CI) 1.05, 3.13). A considerably high proportion of chewers (29.9%) than non-chewers (20.6%) had sub-optimal diastolic blood pressure (> 80 mmHg). The mean (sd) diastolic blood pressure was significantly higher among Khat chewers [75.0 (11.6)] than non-chewers [72.9 (11.7)], P < 0.05. Similarly, Khat chewers had significantly higher mean (sd) heart rate [76.3 (11.5)] than non-chewers [73.9 (12.6)], P < 0.05. There was no significant difference in mean systolic blood pressure between the two groups.

CONCLUSION

Regular chewing of Khat is associated with elevated mean diastolic blood pressure, which is consistent with the peripheral vasoconstrictor effect of Cathinone. Regular Khat chewing may have sustained effects on the cardiovascular system that can contribute to elevated blood pressure at the population level.

Khat chewing and smoking effect on oral mucosa: a clinical study

Khat (Catha Edulis Forskal) is widely cultivated in Yemen and East of Africa. The habit of chewing tender leaves and twigs of khat is deep-rooted in Yemen. Our study investigates the chronic khat chewing and smoking effect on oral mucosa. The sample (n=79) consists of two main groups, khat chewers (n=54) and control groups (n=25). Khat chewers group is divided into 4 subgroups according to duration of khat chewing and smoking habit. The control group is divided into 2 subgroups according to smoking habit. Whitening with mild corrugation, frictional keratosis and frictional keratosis with mild or sever corrugation were the clinical findings. One hundred percent of clinical findings were present on buccal mucosa of chewing side of both smokers and non-smokers whatever the duration of khat chewing period. On the vestibular and mucobuccal fold mucosa, (100 % and 73.3 %) and (60 % and 43.7 %) of the khat chewers group had clinical findings on chewing side of smokers and non-smokers according to khat chewing duration respectively. There was clinical relationship between these lesions and khat chewing, but not smoking. Khat chewing causes oral white lesions on the chewing side and it is found that smoking, clinically, does not exacerbate such lesions.

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.

Meth/amphetamine use and associated HIV: Implications for global policy and public health

Amphetamine type stimulants (ATS) have become the focus of increasing attention worldwide. There are understandable concerns over potential harms including the transmission of HIV. However, there have been no previous global reviews of the extent to which these drugs are injected or levels of HIV among users. A comprehensive search of the international peer-reviewed and grey literature was undertaken. Multiple electronic databases were searched and documents and datasets were provided by UN agencies and key experts from around the world in response to requests for information on the epidemiology of use. Amphetamine or methamphetamine (meth/amphetamine, M/A) use was documented in 110 countries, and injection in 60 of those. Use may be more prevalent in East and South East Asia, North America, South Africa, New Zealand, Australia and a number of European countries. In countries where the crystalline form is available, evidence suggests users are more likely to smoke or inject the drug; in such countries, higher levels of dependence may be occurring. Equivocal evidence exists as to whether people who inject M/A are at differing risk of HIV infection than other drug injectors; few countries document HIV prevalence/incidence among M/A injectors. High risk sexual behaviour among M/A users may contribute to increased risk of HIV infection, but available evidence is not sufficient to determine if the association is causal. A range of possible responses to M/A use and harm are discussed, ranging from supply and precursor control, to demand and harm reduction. Evidence suggests that complex issues surround M/A, requiring novel and sophisticated approaches, which have not yet been met with sufficient investment of time or resources to address them. Significant levels of M/A in many countries require a response to reduce harms that in many cases remain poorly understood. More active models of engagement with M/A users and provision of services that meet their specific needs are required.

New therapeutic potential for psychoactive natural products

Much of our knowledge in neuroscience was discovered through the study of mind-altering natural products. However, although much has been learned about human physiology and basic biological processes, the underlying causes of CNS disorders and other disease states are still elusive. Based on its main past successes, the continued study of mind-altering compounds promises to yield novel agents that may be developed into medications and to identify new targets for the treatment of diseases. This Highlight describes the history of investigations into several classes of mind-altering natural products and relates recent and potential therapeutic uses for these agents.

Free radicals are present in human serum of Catha edulis Forsk (Khat) abusers

OBJECTIVE

Khat (Catha edulis Forsk) is a naturally occurring drug with an amphetamine-like structure and action. It has been postulated that amphetamine induces free radical formation. On this basis, we have hypothesized that Khat may promote synthesis of reactive oxygen and nitrogen species in the same way that amphetamine promotes free radical production.

MATERIALS AND METHODS

Forty male subjects were enrolled in two groups: those with a chronic Khat chewing habit (n=20), and those without a chewing habit (controls; n=20). Both groups were matched with regard to age. Total antioxidant capacity and cholinesterase (AChE) activity were assayed.

RESULTS

This study showed that Khat consumption inhibited serum free radical scavenging enzymes, resulting in significant elevations in free radical loads (p=0.01; n=20). We also showed that serum acetyl cholinesterase (AChE) was significantly inhibited in the Khat chewing group (p=0.002; n=20).

CONCLUSION

These results show for the first time that Khat may contribute to high levels of free radicals. In addition, the presence of pesticides in Khat leaves is implicated in the inhibition of AChE activity.

Natural products as tools for neuroscience: discovery and development of novel agents to treat drug abuse

Much of what we know about the neurosciences is the direct result of studying psychoactive natural products. Unfortunately, there are many gaps in our understanding of the basic biological processes that contribute to the etiology of many CNS disorders. The investigation of psychoactive natural products offers an excellent approach to identify novel agents to treat CNS disorders and to find new chemical tools to better elucidate their biological mechanisms. This review will detail recent progress in a program directed toward investigating psychoactive natural products with the goal of treating drug abuse by targeting kappa opioid receptors.

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.

Extraction and microencapsulation of khat: effects on sexual motivation and estradiol level in female rats

INTRODUCTION

Khat (Catha edulis) is an evergreen tree/shrub that is thought to affect sexual motivation or libido. Its positive effect on sexual desire is more frequently observed in females than in males and occurs when khat is chewed. Thus, khat's effects on sexual behavior may depend on the release mode of its active constituent.

AIM

This study aimed to investigate the effect of dried khat alkaloids on the sexual motivation and estradiol levels of female rats, with special emphasis on the importance of the sustained release effect.

METHODS

Dried khat leaves were extracted and isolated. The alkaloids in khat extract were identified and calculated using thin layer chromatography and high-performance liquid chromatography. The isolated khat extract was microencapsulated using a phase separation coacervation method. The morphology, particle size, yield, drug loading, and entrapment efficiency were evaluated. The in vitro release and stability of alkaloids in khat extract and in khat extract microcapsules were determined. The effect of khat extract microcapsules and varying doses of khat extract on sexual motivation in female rats were investigated. Additionally, estradiol levels, vaginal secretions and vaginal pH were determined.

MAIN OUTCOME MEASURES

The differences in the effect of khat extract and khat extract microcapsules on sexual motivation, vaginal secretion and estradiol levels in female rats were compared. Results. Cathine and norephedrine were identified in the isolated khat extract at composition of 81.3% and 17.2%, respectively. Among the formulations studied, khat extract microcapsules of formulation 2:3:5 (containing a ratio of khat extract to ovalbumin to gelatin of 2:3:5) were found to exhibit higher yield, loading, and entrapment efficiency. Khat extract microcapsules showed sustained in vitro release and were more stable than khat extract. In addition, khat extract microcapsules enhanced sexual motivation, increased vaginal secretions, and upregulated estradiol level in female rats.

CONCLUSION

The sustained release of alkaloids from dried khat has significantly enhanced the sexual motivation and increased the estradiol level of female rats. Thus the release of dried khat alkaloids from microcapsules might be an effective means of enhancing the libido in females.

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.

Dietary trace amine-dependent vasoconstriction in porcine coronary artery

BACKGROUND AND PURPOSE

The dietary trace amines tyramine and beta-phenylethylamine (beta-PEA) can increase blood pressure. However, the mechanisms involved in the vascular effect of trace amines have not been fully established. The purpose of this study was to evaluate whether trace amine-dependent vasoconstriction was brought about by tyramine and beta-PEA acting as indirect sympathomimetic agents, as previously assumed, or whether trace amine-dependent vasoconstriction could be mediated by recently discovered trace amine-associated (TAA) receptors.

EXPERIMENTAL APPROACH

The responses to p-tyramine and beta-PEA were investigated in vitro in rings of the left anterior descending coronary arteries of pigs.

KEY RESULTS

p-Tyramine induced a concentration-dependent (0.1-3 mM) vasoconstriction. The maximum response and pD(2) value for p-tyramine was unaffected by endothelium removal or pre-treatment with antagonists for adrenoceptors, histamine, dopamine or 5-HT receptors. beta-PEA also produced a concentration-dependent (0.3-10 mM) vasoconstriction which was unaffected by endothelium removal, beta-adrenoceptor or 5-HT receptor antagonists. A substantial, but reduced, response to beta-PEA was obtained in the presence of prazosin (alpha(1)-adrenoceptor antagonist), haloperidol (D(2)/D(3) dopamine receptor antagonist) or mepyramine (H(1) histamine receptor antagonist). The pD(2) value for beta-PEA was unaffected by any of the antagonists tested.

CONCLUSIONS AND IMPLICATIONS

Vasoconstriction induced by p-tyramine does not involve an indirect sympathomimetic effect, although vasoconstriction caused by beta-PEA may occur, in part, by this mechanism. We therefore propose that trace amine-dependent vasoconstriction is mediated by phenylethylamine-specific receptors, which are closely related to or identical to TAA receptors. These receptors could provide a target for new antihypertensive therapies.

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".