warfarin, Coumadin, Jantoven (cont.)

Medical Author:
Medical Editor:

PRESCRIPTION: Yes

GENERIC AVAILABLE: Yes

PREPARATIONS: Tablets: 1, 2, 2.5, 3, 4, 5, 6, 5, 7.5 and 10 mg. Powder for Injection: 5 mg/vial

STORAGE: Warfarin should be stored at room temperature, 59 F to 86 F (15 C to 30 C), in tight, light resistant container.

PRESCRIBED FOR: Warfarin is used in treating patients with deep vein thrombosis (DVT) to prevent extension of the clot, and to reduce the risk of pulmonary embolism. Patients with pulmonary embolism are treated with warfarin to prevent further emboli. Warfarin also is used in patients with atrial fibrillation or artificial heart valves to reduce the risk of strokes, and after a heart attack. It also is helpful in preventing blood clots from forming in certain orthopedic surgeries such as knee or hip replacements. Warfarin is used in preventing closure of coronary artery stents due to clotting.

DOSING: Warfarin may be taken with or without food. Since warfarin is metabolized (inactivated) by the liver and then excreted by the kidneys, dosages need to be lowered in patients with liver and kidney dysfunction. Frequent blood tests (INR test) are performed to measure the effect of warfarin and to adjust dosing. There are published INR ranges for the various uses of warfarin. Treatment usually is started at 2 to 5 mg once daily and the dose is adjusted based in INR tests. Patients typically require 2 to 10 mg of warfarin daily.

DRUG INTERACTIONS: Many drugs, both prescription and nonprescription (OTC), can affect the anticoagulant action of warfarin or increase the risk of bleeding. Patients on warfarin should regularly consult their doctor before instituting any medications on their own. It also is advisable for patients on warfarin to carry identification such as bracelets to alert other health professionals to the presence of anticoagulation. Following are a few examples of drugs that interact with warfarin. Drugs the increase the effect of warfarin by reducing the breakdown of warfarin include amiodarone (Cordarone), trimethoprim/sulfamethoxazole (Bactrim), fluconazole (Diflucan), itraconazole (Sporanox), fluvastatin, fluvoxamine, metronidazole miconazole, voriconazole (Vfend), zafirlukast (Accolate), ciprofloxacin (Cipro), cimetidine, atorvastatin (Lipitor), clarithromycin (Biaxin), fluoxetine (Prozac), indinavir (Crixivan), and ritonavir (Norvir).

Medically Reviewed by a Doctor on 1/4/2013


Report Problems to the Food and Drug Administration

You are encouraged to report negative side effects of prescription drugs to the FDA. Visit the FDA MedWatch website or call 1-800-FDA-1088.

Pill Finder Tool

Need help identifying pills and medications?
Use the pill identifier tool on RxList.


Back to Medications Index