Doctors prescribe Plavix, generically known as clopidogrel, to prevent atherothrombic events like strokes and heart attacks in high-risk patients. Patients at risk for these events include those with coronary artery disease, high blood cholesterol, high blood pressure, diabetes and those who smoke, according to the "Journal of the National Medical Association." Although doctors don't specifically forbid any vitamins for patients taking Plavix, you should inform your doctor before taking any vitamins, especially vitamin E or K, because they may inhibit or enhance the effects of Plavix.
Mechanism of Action
Plavix contains clopidogrel hydrogen sulfate, a substance that inhibits adenosine diphosphate, ADP, from binding to platelets, the specialized cells in the blood that aggregate together to prevent excessive bleeding. ADP makes the platelets clump together, allowing blood clots to form. In blood vessels this action is undesirable because blood clots can travel to the brain to cause a stroke or the heart to cause a heart attack. People with atherosclerosis -- the formation of plaque that consists of cholesterol, fat, and other substances in the blood vessels -- have a higher risk of developing blood clots than those who don't. When plaque becomes weak, it can rupture. The rupture attracts platelets, resulting in the formation of a blood clot.
Vitamin E
Vitamin E exists in eight different forms, but your body only recognizes and can use alpha-tocopherol. Vitamin E acts as an antioxidant, which means it protects cells from the harmful effects of free radicals -- the negatively charged particles produced during normal biochemical reactions in the body. Vitamin E can inhibit the activity of protein kinase C, an enzyme important for smooth muscle cells and platelets. Vitamin E may help slow the progression of heart disease by promoting the dilation of blood vessels and inhibiting the aggregation of platelets.
Vitamin K
Vitamin K plays a vital role in blood coagulation. Your body needs vitamin K to activate a specialized group of proteins known as clotting factors. A vitamin K deficiency increases the risk for uncontrolled bleeding. Another class of medications known as anticoagulants also prevents the formation of blood clots, but the mechanism of action differs from Plavix. These medications, like warfarin, inhibit the action of vitamin K.
Interactions
High doses of vitamin E can inhibit blood coagulation and increase your risk for bleeding, according to the National Institutes of Health Office of Dietary Supplements. Since Plavix prevents the aggregation of platelets, it also affects the ability of blood to coagulate. Taking vitamin E may enhance the effects of Plavix and increase the risk of side effects like easy bruising, unusual bleeding and bleeding under the skin. Although vitamin K does not directly interfere with Plavix, taking vitamin K supplements increases the risk for blood clot formation, which can decrease the effectiveness of Plavix.
References
- National Institutes of Health Office of Dietary Supplements: Vitamin E
- Linus Pauling Institute: Vitamin K; Jane Higdon, Ph.D., et al.; May 2004
- PubMed Health: Clopidogrel
- "Journal of the National Medical Association"; Antiplatelet Therapy in Populations at High Risk for Atherothrombosis; D. Faxon, et al.; May 2006
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