Oral anticoagulant drugs

Article Abstract:

Anticoagulants, drugs that prevent clots from forming, have been greatly improved since the vitamin K-antagonists were reviewed in The New England Journal of Medicine 20 years ago. Several effective anticoagulants can be taken orally (by mouth). Warfarin is now the most widely used anticoagulant in the United States because it is effective and relatively safe. How anticoagulants prevent clotting by interfering with the action of vitamin K is described. Drug metabolism, anticoagulant action in the body, and interactions with other drugs, including aspirin, are discussed and outlined in tables. Measurement of the therapeutic range and dosing considerations are also noted. Anticoagulant drugs are used for a variety of conditions, including prevention of blood clots after hip surgery, treatment of deep-vein thrombosis (clots), prevention of stroke and pulmonary embolism (blockage of the pulmonary artery) after a heart attack or the placement of a prosthetic heart valve, and reduction of stroke and systemic embolism in patients with atrial fibrillation (an abnormal heart rhythm). Of the adverse effects associated with anticoagulants, bleeding is the most serious, especially among patients over the age of 65 who often have other complications. Coumarin causes abnormalities in the fetus during any trimester of pregnancy, and warfarin should not be used during the first trimester. Heparin is preferred if anticoagulant therapy is necessary for a pregnant woman. Easier and faster tests to monitor anticoagulant dosages are becoming available, some of them for home use. The effectiveness of using lower doses of warfarin is being studied, including very-low-intensity regimens in combination with aspirin for the prevention of heart attacks. ..DE: (Consumer Summary produced by Reliance Medical Information, Inc.)

Health aspects, Prevention, Heart attack, Coumarins

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Trial of different intensities of anticoagulation in patients with prosthetic heart valves

Article Abstract:

The major complications seen in patients with artificial heart valves are thrombosis, the formation of blood clots, and thromboembolism, the formation of small travelling blood clots which can clog arteries, interfering with blood flow to vital organs including the heart and brain. Warfarin, a compound that inhibits the clotting process, is routinely given to patients with artificial valves to reduce the risk of thrombosis and thromboembolism. Unfortunately, normal clotting is inhibited as well, and this can lead to internal bleeding. To evaluate the dose which provides maximum benefit to the patient, 258 patients with prosthetic heart valves were given either a moderate or a high-intensity warfarin treatment. The treatment intensity was modulated by changing the patient's prothrombin-time ratio, a measure of clotting effectiveness. It was found that thromboembolism occurred with approximately equal frequency in both groups, whereas bleeding episodes were significantly increased in the high-intensity treatment group. A moderate treatment, with a prothrombin-time ratio of 1.5, provides adequate protection at a lower risk than high-intensity treatment. (Consumer Summary produced by Reliance Medical Information, Inc.)

Causes of, Thromboembolism, Heart valve prosthesis, Artificial heart valves

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The effect of aggressive lowering of low-density lipoprotein cholesterol levels and low-dose anticoagulation on obstructive changes in saphenous-vein coronary-artery bypass grafts

Article Abstract:

Fewer blood vessels grafted during bypass surgery may later become blocked if the patient takes medication that aggressively lowers low-density lipoprotein (LDL) cholesterol levels. LDL cholesterol levels and the number of blocked vessel grafts were determined after treatment with one of two lovastatin strengths and warfarin or placebo in 1351 patients with previous bypass surgery. Patients treated aggressively had significantly lower LDL cholesterol levels and percentage of blocked vessels. The addition of warfarin did not significantly reduce the percentage of blocked vessels.

Blood vessels, Coronary artery bypass, Saphenous vein

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