A significant number of patients on Warfarin also take herbal and/or dietary supplements which can interact in a negative way with the blood thinning medication; unfortunately, the majority of patients who do this are unaware, scientists from the Intermountain Medical Center Heart Institute in Salt Lake City explained at the American Health Association's Annual Scientific Session 2010, Chicago. They found that of the 100 most popular OTC supplements, over two-thirds interfered with how Warfarin worked.

Dietary and herbal supplements are extremely popular, especially among patients with bone problems. Those with atrial fibrillation are commonly prescribed Warfarin to protect them against stroke.

Intermountain Medical Center Heart Institute scientists along with qualified dieticians from Utah State University interviewed 100 individuals, all of them diagnosed with atrial fibrillation. Their aim was to find out how much they knew about the danger of interactions (clashes) between Warfarin and supplements.

Warfarin, a medication to prevent dangerous blood clots from developing, may be prescribed for people with irregular heartbeat, prosthetic heart valves, and also heart attack patients, mainly to lower the risk of venous thrombosis and pulmonary embolism.

They identified 35 patients who were taking supplements while on Warfarin. 54% of them had no idea of the interaction risk.

Atrial fibrillation patients most commonly buy vitamins, fish oils, coenzyme Q10, and glucosamine/chondriotin.

Study author and heart rhythm specialist, T. Jared Bunch, MD, said: "This is an alarming finding," Bunch explained that these supplements and blood thinning medications "compete" in the liver, altering the way the medication works. The Warfarin, for example, either becomes over- or under-active, resulting in the blood becoming too thin (risk of bleeding) or too thick (risk of stroke).

Dr. Bunch said: "This data is important because it demonstrates how important it is for physicians to understand our patients' knowledge about and use of these products. We need to do a better job of teaching our patients about the dangers of mixing warfarin with these products." The researchers found that 23% of the patients in their study who were on Warfarin and also took supplements had episodes of unexplained bleeding, compared to 17% of the other patients. 14% of those taking supplements while on Warfarin needed blood transfusions, compared to 10% among the others.

They also found that the supplement takers tended to understand their blood thinning medication less - 34% of them were likely to skip their Warfarin and make up for it with a higher dosage next time, compared to 17% among the non-supplement takers.

Dr. Bunch added: "We have also learned that - for whatever reason - patients don't want to tell their doctors that they are taking herbal and dietary supplements. Physicians must be active in asking about supplement use and not place responsibility on patients. We need to tell our patients that it's acceptable to use herbal and drug supplements, but important for them to tell us so that we can educate them about the benefits, dangers, and potential interactions with their other medications." Source: Intermountain Medical Center Heart Institute



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