Anticoagulant therapy is used to prevent the formation of dangerous blood clots. Anticoagulant therapy can be by injection or oral medication. The most commonly used oral medication is warfarin. The most well known brand of warfarin is Coumadin. Warfarin is used to prevent and treat venous thrombosis, pulmonary embolism, complications of atrial fibrillation and cardiac valve replacement, and to reduce the risk of death, second heart attack and stroke after an initial heart attack.

Warfarin works by inhibiting the synthesis of vitamin K dependent clotting factors. Anticoagulant effect generally occurs within 24 hours but peak effect may be delayed 72 to 96 hours. The effect of warfarin may increase as daily maintenance doses overlap. Anticoagulants do not have any effect on clots that have already formed. The goal of therapy is to prevent further extension of the formed clot and to prevent secondary complications.

Frequent monitoring is required to ensure appropriate dosing. The standardized measure of clotting activity is referred to as the INR. Most therapies aim for INR of 2 to 3.5 depending upon the condition. It is important to take doses exactly as ordered. It is also important to take doses at the same time every day. Sickness, diet, medications, and physical activity may affect your INR. Be sure to tell your physician about any changes in lifestyle so your therapy can be monitored accordingly.

To assure the safety of your therapy, you should take your medication exactly as ordered, keep your eating habits and activities similar each day, get your blood tested as scheduled, tell your doctor and pharmacist about any over-the-counter medications and prescriptions you are taking before you change, start or stop any medication, tell your doctor if you get sick, hurt or cut, look for signs of bleeding, tell anyone giving medical or dental care that you take warfarin, wear a medical alert bracelet and refill your prescription as ordered. You should also not take a missed dose to "catch up," and avoid drastic changes in diet, avoid alcohol, and avoid sports or activities that could result in traumatic injury.

It is very important to keep your diet steady. Certain foods contain high or moderate amounts of vitamin K. Any drastic changes in the consumption of these foods can change your INR. Foods that are high in vitamin K include mayonnaise, canola and soybean oils, broccoli, Brussels sprouts, cabbage, collard greens, cucumber peel, endive, scallions, kale, lettuce, mustard greens, parsley, spinach, turnip greens and watercress. Foods with moderate levels of vitamin K include margarine, olive oil, asparagus, avocado, red cabbage, coleslaw, green peas, raw green beans, dill pickles, sauerkraut, and dried soybeans. Any major changes in these foods could require dosage adjustments of warfarin based on INR testing.

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