WARFARIN

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, 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.

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, acetaminophen (Tylenol and others), 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.

PRECAUTIONS: Before taking warfarin, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This medication should not be used if you have certain medical conditions. Before using this medicine, consult your doctor or pharmacist if you have: blood disorders (e.g., hemophilia), bleeding conditions (e.g., active ulcers), uncontrolled severe high blood pressure (malignant hypertension), recent or planned surgery, received certain procedures (e.g., spinal cord injections, major anesthesia). Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, kidney disease, alcohol abuse, tissue damage (e.g., gangrene, necrosis), trauma, high blood pressure, severe diabetes, congestive heart failure, cancer, collagen vascular disease (e.g., lupus, polyarteritis), radiation therapy, underactive or overactive thyroid, poor nutrition, intestinal absorption problems, low blood levels of vitamin K, swelling of the arms/legs (edema), high cholesterol/fat blood levels, catheters in your body (e.g., urinary or intravenous type), side effects with heparin treatment (heparin-induced thrombocytopenia), family members who did not respond to warfarin treatment, conditions that make it difficult to follow a warfarin treatment plan (e.g., dementia, psychosis). Avoid alcohol while taking this drug because it may increase the risk of stomach bleeding. Avoid getting injections into the muscles (intramuscular-IM). If they must be given, limit injections to the arms. The FDA has stated that generic warfarin products are interchangeable. However, consult your doctor and pharmacist before switching warfarin products. If you have an illness or infection that causes vomiting, diarrhea or fever for more than a few days, contact your doctor immediately because these conditions can affect how well this drug works. This medication can cause heavy bleeding. Be extra careful to avoid injuries (e.g., avoid contact sports). Use an electric razor when shaving and a soft toothbrush when brushing your teeth. It is important that all your doctors and dentists know you take warfarin. Caution is advised when using this drug in the elderly because they may be more sensitive to its effects. This medication must not be used during pregnancy because of possible fetal harm and birth defects. Discuss reliable forms of birth control with your doctor. If you become pregnant or think you may be pregnant, inform your doctor immediately. You will be switched over to another anticoagulant (e.g., heparin-type) during pregnancy. Consult your doctor for more information. This medication does not pass into breast milk. While there have been no reports of harm to nursing infants, consult your doctor before breast-feeding.
DRUG INTERACTIONS: This drug should not be used with the following medications because very serious interactions may occur: imatinib, mifepristone. If you are currently using any of these medications, tell your doctor or pharmacist before starting warfarin. Many drugs and herbal products interact with warfarin. Before using this medication, tell your doctor or pharmacist of all prescription and nonprescription/herbal products you may use, especially of: acetaminophen (repeated use or large doses), allopurinol, aminoglutethimide, amiodarone, anabolic steroids (e.g., danazol, stanozolol), certain injectable cephalosporin antibiotics (e.g., cefamandole, cefotetan), macrolide antibiotics (e.g., erythromycin, clarithromycin), certain oral and injectable penicillin-type antibiotics (e.g., dicloxacillin, piperacillin), quinolone antibiotics (e.g., ciprofloxacin, levofloxacin), certain other antibiotics (e.g., chloramphenicol, metronidazole), azole antifungals (e.g., voriconazole, vaginal miconazole), barbiturates (e.g., phenobarbital), birth control pills, certain drugs to treat cancer (e.g., capecitabine, fluorouracil), carbamazepine, drugs to lower cholesterol or triglycerides (e.g., cholestyramine, fenofibrate, gemfibrozil, lovastatin, simvastatin), cimetidine, corticosteroids (e.g., prednisone), disulfiram, glucagon, griseofulvin, herbal/dietary products (e.g., bromelains, co-enzyme Q, danshen, dong quai, garlic, ginkgo biloba, ginseng, St. John's wort), nonsteroidal anti-inflammatory drugs (NSAIDs such as celecoxib, ibuprofen, topical methylsalicylate), omeprazole, propafenone, propoxyphene, quinidine, quinine, rifamycins (e.g., rifampin, rifabutin), certain sedatives (e.g., chloral hydrate, ethchlorvynol, glutethimide), sulfa drugs, sulfinpyrazone, SSRI antidepressants (e.g., fluoxetine, fluvoxamine), tamoxifen, drugs to treat thyroid disease (e.g., levothyroxine, propylthiouracil), vitamin E, vitamin K, zafirlukast. Check all prescription and nonprescription medicine labels carefully since many contain pain relievers/fever reducers (NSAIDs such as ibuprofen, naproxen, or aspirin) which can increase the risk of bleeding/anti-platelet effect when used with warfarin. Low-dose aspirin, as prescribed by your doctor for specific medical reasons such as heart attack or stroke prevention or to prevent clotting of artificial heart valves (usually these dosages are 81-325 mg per day), should be continued. Consult your doctor or pharmacist for more details. Related drugs (anti-platelet drugs such as clopidogrel, dipyridamole, ticlopidine) prescribed for specific medical reasons should be continued, unless otherwise directed by your doctor. Consult your doctor or pharmacist for more details including the possible serious side effects associated with ticlopidine (e.g., immune system problem, liver disease when used with warfarin). While taking warfarin, it is important to eat a normal, balanced diet. The amount of vitamin K in your body affects the way that warfarin works. It is best to avoid sudden changes in your diet, especially unusual increases or decreases in the amount of foods high in vitamin K (e.g., liver, broccoli, cauliflower, cabbage, Brussels sprouts, kale, spinach and other green leafy vegetables, green tea, and certain vitamin supplements). It is best to avoid strictly vegetarian diets that consist of foods high in vitamin K. This product can affect the results of certain lab tests. Make sure laboratory personnel and your doctors know you use this drug.
OVERDOSE: If overdose is suspected, contact your local poison control center or emergency room immediately. US residents can call the US national poison hotline at 1-800-222-1222. Canadian residents should call their local poison control center directly. Symptoms of overdose may include unusual or prolonged bleeding, dark urine or black stools.

NOTES: Do not share this medication with others. Laboratory and/or medical tests (e.g., blood tests such as PT/INR, complete blood count) should be performed periodically to monitor your progress or check for side effects. It is important to keep all lab and medical appointments. Consult your doctor or pharmacist for more details.

MISSED DOSE: If you miss a dose, use it as soon as you remember if it is on the same day. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not double the dose to catch up because this could increase your risk for bleeding. Keep a record of missed doses to give to your doctor or pharmacist. Call your doctor or pharmacist if you miss 2 or more doses in a row.

STORAGE: Store at room temperature between 59-86 degrees F (15-30 degrees C) away from light and moisture. Do not store in the bathroom. Keep all medicines away from children and pets.

MEDICAL ALERT: Your condition can cause complications in a medical emergency. For enrollment information call MedicAlert at 1-800-854-1166 (USA), or 1-800-668-1507 (Canada).