GENERIC NAME: warfarin

BRAND NAME: Coumadin

DRUG CLASS AND MECHANISM: Coumadin is an oral anticoagulant that inhibits the synthesis of clotting factors, thus preventing blood clot formation. Blood clots can occur in the veins of the lower extremities, usually after periods of immobility. These clots can break off and become lodged in the blood vessels of the lung (pulmonary embolism), causing shortness of breath, chest pain, and even life-threatening shock. Blood clots can also occur in the atria of the heart during atrial fibrillation (see Atrial Fibrillation article), and around artificial heart valves. One of these clots can also break off and obstruct a blood vessel in the brain, causing an embolic stroke with paralysis. Coumadin is important in preventing the formation of blood clots. It is also important to prevent extension of clots already formed, and to minimize the risk of blood clot embolization to other vital organs such as the lungs and brain.

PRESCRIPTION: yes

GENERIC AVAILABLE: yes

PREPARATIONS: tablets (1mg, 2mg, 2.5mg, 5mg, 7.5mg, 10mg)

STORAGE: Store at room temperature in tight, light resistant container.

PRESCRIBED FOR: Coumadin is used in treating patients with blood clots in the lower extremities to prevent extension of the clot, and to reduce the risk of pulmonary embolism. Patients with pulmonary embolism are treated with Coumadin to prevent further blood clot emboli. Coumadin is also used in patients with atrial fibrillation and artificial heart valves to reduce the risk of strokes. It is also helpful in preventing blood clot formation in certain orthopedic surgeries such as knee or hip replacements. Coumadin is also used in preventing blood clot closure of coronary artery stents.

DOSING: Coumadin may be taken with or without food. Since Coumadin is metabolized by the liver and excreted by the kidneys, dosages need to be lowered in patients with liver and kidney dysfunction. Frequent blood tests are performed to measure blood clotting time (protime) during Coumadin treatment. Protime results help doctors adjust medication dose to avoid excessive blood thinning and risk of bleeding.

DRUG INTERACTIONS: Many drugs, both prescription and nonprescription (OTC), can affect the anticoagulant action of Coumadin. Some medications can enhance the action of Coumadin and cause excessive blood thinning and life-threatening bleeding. A few examples of such medications include Aspirin, Tylenol, alcohol, ibuprofen (Motrin), cimetidine (Tagamet), oxandrolone (Oxandrin), certain vitamins, and antibiotics. Patients on Coumadin should regularly consult their doctor before instituting any medications on their own. It is also advisable for patients on Coumadin to carry identifications to alert other health professionals.

PREGNANCY: Coumadin should be avoided by pregnant women or women who may become pregnant. Birth defects and fetal bleeding have been reported.

SIDE EFFECTS: The two most serious side effects are bleeding and necrosis (gangrene) of the skin. Bleeding can occur in any organ or tissue. Bleeding around the brain can cause severe headache and paralysis. Bleeding in the joints can cause joint pain and swelling. Bleeding in the stomach or intestines can cause weakness, fainting spells, black tarry stools, vomiting of blood, or coffee ground material. Bleeding in the kidneys can cause back pain and blood in urine. Other side effects include purple, painful toes, rash, hair loss, bloating, diarrhea, and jaundice (yellowing of eyes and skin). Signs of overdose include bleeding gums, bruising, nosebleeds, heavy menstrual bleeding, and prolonged bleeding from cuts.

Additional drug information: Coumadin (warfarin) FDA approved labeling at RxList.
http://www.rxlist.com/coumadin-drug/article.htm

Last Editorial Review: 8/24/1999

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