Drugs that are affected include: calcium channel blockers (Amlodipine™, Felodipine™, etc.), Cyclosporin™, Triazolam™, estrogens, Carbamazepine™, Lovastatin™, and Buspirone™. If you regularly consume grapefruits or grapefruit juice don't stop your usual routine, but ask your Doctor or Pharmacist what should be done.
.....Many people on heart medication may also be taking a blood thinner called warfarin (Coumadin™). Many things can interfere with the action of warfarin including foods and vitamins. Some products can enhance the effectiveness of warfarin, which could lead to bleeding problems. Others can block the effects of Warfarin�, which could lead to the formation of blood clots. You can see why it is important to keep in touch with your Doctor or Pharmacist when you are taking Warfarin�.
.....There are several products that can enhance the effectiveness of warfarin. You should be particularly careful with these herbal products; garlic, ginger, and ginkgo biloba. All of these products have the ability to thin the blood. If used together with warfarin, the results could be dangerous. It might be best to avoid these products while taking warfarin. Larger doses of Vitamin E, over 800IU, have also been shown to enhance the effects of warfarin. Other natural products you might want to avoid if you are taking prescription blood thinners include: dong quai, fish oils, bromelain, feverfew, horse chestnut, ginseng, white willow, and ipriflavone. If you have been taking these supplements, don't stop your usual routine, but ask your Doctor or Pharmacist what should be done.
.....Other supplements can hinder the action of warfarin, leading to a higher risk of developing blood clots. This can increase the risk of heart attacks or strokes. These products affect warfarin by either impeding its absorption or because of their high vitamin K content. Vitamin K is needed by your body to help the blood clot. Warfarin partially blocks the effects of Vitamin K. If you change your diet in a major way, or take products high in vitamin K, this can hinder the effects of Warfarin™. Food and herbs that are high in vitamin K include: alfalfa, goldenseal, plantain, stinging nettle, kale, green tea, avocado, spinach and other dark green leafy vegetables. The herbal laxatives mentioned above can prevent warfarin from being absorbed into the body. Again if you have been taking these supplements, don't stop your usual routine, but ask your Doctor or Pharmacist what should be done.
.....If you are thinking about trying a new medication, whether it is a vitamin, herbal supplement or prescription drug, talk to your Doctor or Pharmacist. They can determine if this new product is fine to take along with the medicines you are already taking. With their help you can ask yourself, "Are the possible benefits from taking this product worth the risk?" As your most accessible health care professional, your Peoples Drug Mart Pharmacist is the ideal person to ask.

Written by: Ian Lloyd BSc. Pharm., a community pharmacist in Victoria B.C.