Shaping a Research Agenda on Natural Product-Drug Interactions
At NCCAM, one of the interesting things we are doing with respect to natural products is moving ahead on a plan for systematic evaluation of the ways in which they interact with prescription medications.
Numerous surveys have found that many people, particularly the elderly, take drugs and natural products (whether in the form of dietary supplements or foods) together. There is the potential for a wide range of effects—including mild to serious adverse events—from such combinations. As one example, St. John's wort has clinically significant interactions with many widely prescribed drugs, including birth control pills, anticoagulants, antiretrovirals, antidepressants, antiseizure drugs, and immunosuppressants. Interactions can affect drugs' concentrations in the body and hence their clinical effects. In light of the widespread availability and use of natural products, research on their safety (including interactions) is a major priority for NCCAM. At present, the data on interactions is very limited, highly variable, and mostly in the form of preclinical models, case studies, and hypothetical arguments.
Conducting research in this area is very challenging. There are an overwhelming number of supplements in the marketplace and a nearly infinite number of possible ways they can be combined with pharmaceuticals. Additional challenges include decisions about assays to use, appropriate patient populations for clinical studies, etc. NCCAM has been addressing these issues by:
- Implementing a three-phase initiative for systematic in vitro and in vivo characterization of potential supplement-drug interactions
- Forming an expert panel from the academic, research, and government communities and hosting two roundtable meetings, and
- Developing, with the panel, criteria for decision making on substances to include in a testing matrix.
A report on the Dietary Supplement-Drug Interaction Expert Panel Meeting, held in April 2013, is now available online. Our goals are to not only bring the best science to the study of interactions, but to plan for disseminating those findings to the public and health-care providers so they can inform decisions on patient care. Now is also an opportune time to reiterate NCCAM's message on the importance of open patient-provider communication regarding complementary health approaches, including natural products, so that care can be as coordinated and safe as possible.