HERB-DRUG INTERACTIONS: AN OVERVIEW OF MECHANISMS AND CLINICAL ASPECTS

Millions of people today use herbs either as food or in the form of medicine along with prescription and non prescription medications. Although considered natural and safe, many of these herbs can interact with other medications, causing either potentially dangerous side effects and/or reduced benefits from the medication. Both pharmacokinetic and pharmacodynamic mechanisms are involved in these interactions and majority of the herb-drug interactions were found to be mediated by metabolic inductions or inhibitions. It should be understood that herbal preparations contain multiple active phytochemicals in varying proportions which can, like any other active pharmacological substance, alter the enzymatic systems, transporters and/or the physiologic processes. The purpose of this review is to discuss evidence based mechanisms and clinical implications of such herb-drug interactions and to increase awareness on herb-drug interactions by reviewing published clinical and preclinical studies. As the incidence and severity of herb-drug interactions is increasing due to a worldwide rise in the use of herbal preparations, more clinical data regarding herb-drug interactions are needed to make decisions regarding patient safety. The increasing understanding of pharmacokinetic herb-drug interactions will make health care professionals and patients pay more attention to the potential interactions.