Khat: A Substance of Growing Abuse with Adverse Drug Interaction Risks

The growing global availability of the stimulant shrub, khat, has aroused widespread concern. This paper is a review of possible adverse interactions between khat and conventional drugs. Khat chewing has been shown to reduce the bioavailabilities of orally co-administered antibiotics, ampicillin, amoxicillin, cephradine and tetracyclineHCl, and the antimalarial drug, chloroquine. The cardiovascular and central nervous system (CNS) stimulant effects of monoamine oxidase inhibitors (MAOI) and amphetamine-like drugs have been described to be enhanced by khat chewing. Khat is recognized to have the ability to counteract the effects of antihypertensive, antiarrhythmic and local anesthetic drugs, and to offset the cardioprotective action of aspirin. Depending on the amount or duration of consumption, khat has been reported to variably affect the actions of general anesthetics. Khat is likely to augment the effects and/or toxicity of different drugs due to its inhibitory action on the drug metabolizing enzyme CYP2D6. While specific mechanisms have been suggested for some of the khat-drug interactions reported, the mechanisms for other interactions are less clear. Despite the above observations, the literature reviewed is associated with a number of shortcomings, suggesting the need for further research and documentation on this area of knowledge. It is recommended that, in the interim, health care providers should be more familiar with the known and suspected adverse khat-drug interactions in order to optimally serve their patients who chew khat.