Natural products drug interactions with

The nature of plants having secondary metabolites as defensive agents greatly increases the expectation that there will be interactions with other botanical products and drugs. If well-established traditional botanical products are used according to directions, they are likely a low risk. Risk increases when botanical products are combined with conventional drug therapies and lies in the possibility of unknown natural product-drug interactions. Other risks include product deviation due to misidentification of species, the lack of standardization, or adulteration. Most of the interactions have been reported with cytochrome P-450 (CYP) 3A4, but there are interactions with other metabolism enzymes and transport proteins. 

However, the information derived from a detailed pharmacokinetic study will help to anticipate potential botanical product-drug interactions, to optimize the bioavailability, the quality, and hence the efficacy of herbal medicines, to support evidence for the synergistic nature of herbal medicines, and to better appreciate the safety and toxicity of the plant. Because pharmacokinetic studies with herbal medicines are often complicated by their chemical complexity and by the fact that the active compounds are often unknown, it could be one future issue to assess bioavailability by measuring surrogate parameters in plasma or tissue instead of directly assaying putative active compounds in the blood. In summary, to use HMPs in an evidence-based approach and to achieve the status rational phytomedicine, more experimental studies are needed to characterize the bioavailability and pharmacokinetics of botanical products. 

In addition to food- or nutrient-based interactions in the metabolism of drugs, it has become quite clear in recent years that so-called dietary supplements including botanicals have the potential to participate in such interactions. The latter observation has special relevance because of the extensive use of such products worldwide ( 12 billion per year in the United States alone), their easy commercial availability (no prescription required), and their common use with prescribed drugs. Furthermore, many people consider such natural products to be safe and free of any bad effects (it should be pretty easy to recall many poisons... 

The exact mechanism by which chemical exposures cause MCS is unknown. It is believed that a two-step process occurs. First, an initial exposure or chronic exposures interacts with a susceptible individual, leading to loss of that person s prior, natural tolerance for everyday, low-level chemicals, as well as certain foods, drugs, alcohol, and caffeine. In the second stage, symptoms are thereafter triggered by extremely low doses of previously tolerated products and exposures.2 This theory is called toxicant-induced loss of tolerance or TILT. 3... 

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