Information
Top 10 Variables: Dietary Supplements
Monday, October 1, 2007
PTINR.com Staff
Both warfarin package insert and experts at the American College of Chest Physicians caution against dietary supplement use
Dietary supplements are products that fall into their own category. Dietary supplements don’t fall into the typical over the counter medication class. They are not regulated like prescription drugs. As more patients are turning to alternative medicines, dietary supplements are playing an increasing role in dangerous drug interactions in patients taking warfarin (Coumadin ®) (brand: Coumadin®)
Dietary supplements include herbal products, holistic products, and natural products. The internet has exploded with banner ads and offers for alternative choices to prescription drugs. Many dietary supplements have their origin from plant or plant extracts. Warfarin interactions with dietary supplements are common and well documented.
Dietary supplements are regulated by the FDA under a completely different set of pharmaceutical guidelines despite consumers use these products as medications. Under the Dietary Supplement Health and Education Act of 1994 (DSHEA) the manufacturers are responsible for demonstrating product safety. The Federal Trade Commission governs the advertising of dietary supplements. Some have drawn parallelisms of this to putting the fox in charge of the hen-house.
Patients have less concern for dietary supplements than they do for over the counter medications when it comes to drug interactions. The false sense of security comes, in part, due to the fact that dietary supplements have, for the most part, natural origins. A drug interaction is a drug interaction regardless of the origin of the compound. Prolongation of the INR in patients taking warfarin increases bleeding risks. Some natural products can reduce the effectiveness of warfarin, lowering the INR and increasing the risk of dangerous clot formation in patients predisposed to clot formation.
Patients on warfarin should treat natural medicines as they would prescription drugs with regard to dangerous, possibly life-threatening side effects as seen in other drug interactions.
Supplements are required by law to carry the following label:
The product and the claim made about specific products have not been evaluated by the United States Food and Drug Administration and are not intended to diagnose, treat, cure or prevent disease.
Patients who experience fluctuations in INR tests should determine if they have started or stopped a dietary supplement, including vitamin preparations. Natural medicines are a new variable for physicians to manage and every patient should discuss the intended use of these products. Increases and decreases in INRs have been reported with natural medicine use. Only a doctor should adjust the dose of warfarin based on dietary supplement use by patients.
The warfarin package insert publishes a partial list of natural products and their influence on INR test results. PTINR.com provides information on natural medicines in our Drug Interaction section.