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Herbal and Dietary Supplements – Drug Interactions in Patients with Chronic Illnesses

Posted April 8th, 2008 by Kathy Shattler

herbal supplements and drug interactionsMore and more you will find on the doctor’s admission papers a place to put your vitamins, botanicals and other supplements that you may be taking over the counter. Dietary supplements are not subjected to the safety trials and pre-marketing approval process that is required of prescription drugs. The resulting caveat is a black hole in the knowledge base between dietary supplements and drug interactions, especially among patients with chronic disease who may be on multiple supplements.

More and more studies are coming out in this area. Just recently, in the January issue of the American Academy of Family Physicians, it was reported that two out of three patients do not report their dietary prescription use. They further stated that herbs, vitamins and other dietary supplements may augment or antagonize the actions of both prescription and nonprescription drugs already being prescribed by physicians. The information for many dietary supplements is deficient and sometimes supported only by case studies rather than randomized, better controlled clinical trials.

The meta-analysis showed that the most deleterious effects found from the review of literature was related to taking anticoagulants, cardiovascular medications, oral hypoglycemic and antiretrovirals. There are case reports of reductions in International Normalized Ratio (INR) in patients taking St. John’s wort and warfarin. Other case studies have shown a reduction in verapamil, statins, digoxins and antiretrovirals in patients taking St. John’s wort. The researchers included a table of herbal and supplement drug interactions noting that St. John’s wort was one of the most frequent offenders (or, perhaps, one of the most frequently studied).

About the Author

Kathy ShattlerKathy Shattler received her Master of Science degree from Michigan State University in E. Lansing Michigan in Human Nutrition. Her twenty-two years of practice includes holding positions as a Lecturer, Chief Clinical Dietitian and Program Manager. Kathy is the Founder of Nutri-Care Consulting and is currently the Nutrition Director of www.CEU4U.COM, an online continuing education management company for Registered Dietitians and Dietetic Technicians.


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