The subcutaneous and intravenous methods use the naturally occurring substance heparin. The intravenous method, in which medicine is injected directly into the blood stream via a vein, uses unmodified heparin. We discuss here only oral anticoagulation, using warfarin, because that is the method of long-term anticoagulation favored by most people. The brand name form of warfarin is Coumadin , which many clinicians prefer because of its reliability. Experience has proven that when cost-cutting efforts have forced people to change the form of warfarin they take every day, they have an increased rate of complications.
Warfarin is taken once a day.
The reason for all this testing is that the dose required for safe and effective anticoagulation varies a lot from person to person. Moreover, it varies in the same person from week to week depending on the diet. Because warfarin acts by opposing the body's ability to use Vitamin K to the proteins it needs for normal coagulation, the dose of warfarin changes if a person eats more or less Vitamin K than he or she usually does. Everyone who takes warfarin should get a booklet from his or her doctor listing the amount of Vitamin K in a variety of foods. Foods that contain a particularly large amount of Vitamin K include beef liver, pork liver, green tea, broccoli, chick peas, kale, turnip greens, and soybean products including soybean oil, soybeans themselves, soy milk, and tofu.