• Thromboembolic disorders

Warfarin Generic Name & Formulations

General Description

Warfarin sodium 1mg, 2mg, 2½mg, 3mg, 4mg, 5mg, 6mg, 7½mg, 10mg (dye-free); scored tabs.

Pharmacological Class

Coumarin anticoagulant.

How Supplied

Contact supplier

Warfarin Indications


Venous thrombosis. Pulmonary embolism. Thromboembolic complications from atrial fibrillation and/or cardiac valve replacement. Reduce risk of death, recurrent MIs, and thromboembolic events (eg, stroke, systemic embolization) post-MI.

Warfarin Dosage and Administration


Individualize. ≥18yrs: Initially 2–5mg once daily. Usual maintenance: 2–10mg once daily. Variations in CYP2C9 or VKORC1 enzymes, elderly, debilitated, Asians: use lower initial and maintenance doses. Closely monitor INR; adjust dose based on response and clinical condition. Conversion from heparin or other anticoagulants: see full labeling.


<18yrs: see full labeling.

Warfarin Contraindications


Hemorrhagic tendencies. Blood dyscrasias. Recent CNS, ophthalmic, or traumatic surgery. Bleeding tendencies associated with certain conditions. Threatened abortion, eclampsia, and preeclampsia. Unsupervised patients with potential high levels of non-compliance. Major regional or lumbar block anesthesia. Spinal puncture and other procedures with potential uncontrollable bleeding. Malignant hypertension. Pregnancy in women without mechanical heart valves.

Warfarin Boxed Warnings

Boxed Warning

Bleeding risk.

Warfarin Warnings/Precautions


Risk of major or fatal bleeding. Monitor INR frequently. History of GI bleed. Hypertension. Cerebrovascular disease. Anemia. Malignancy. Trauma. Discontinue if tissue necrosis, calciphylaxis, systemic atheroemboli or cholesterol microemboli occurs; consider alternative therapy if needed. Heparin-induced thrombocytopenia with or without thrombosis syndrome; do not use as initial therapy. Hepatic or renal impairment; monitor INR/bleeding more frequently. Infection. Disturbances of intestinal flora. Indwelling catheter. Protein C and S deficiency. Polycythemia vera. Vasculitis. Diabetes. Diarrhea. Poor nutritional status. Steatorrhea. Vitamin K deficiency or intake. Hereditary warfarin resistance. Eye surgery. Dental procedures. Elderly; monitor more frequently. Asian. Debilitated. Anticoagulation may persist 2–5 days after discontinuation. Write ℞ using fractions rather than decimals. Pregnancy in women with mechanical heart valves. Females of reproductive potential should use effective contraception during therapy and for at least 1 month after final dose. Nursing mothers.

Warfarin Pharmacokinetics

See Literature

Warfarin Interactions


See full labeling. Potentiated by CYP2C9, 1A2 and/or 3A4 inhibitors. Antagonized by CYP2C9, 1A2 and/or 3A4 inducers. Caution with drugs that can increase risk of bleeding (eg, anticoagulants, antiplatelets, NSAIDs, SSRIs) or herbal products (eg, garlic, ginkgo biloba, co-enzyme Q10, St. John's wort, ginseng, echinacea, grapefruit juice, goldenseal). Closely monitor INR when starting or stopping any antibiotic or antifungal agent. Cholestatic hepatitis with concomitant ticlopidine.

Warfarin Adverse Reactions

Adverse Reactions

Tissue or organ hemorrhage, hypersensitivity reactions, hepatic disorders, GI disorders, skin disorders, tracheal or tracheobronchial calcification, chills; skin or tissue necrosis, calciphylaxis, systemic atheroemboli and cholesterol microemboli (eg, purple toes syndrome), acute kidney injury.

Warfarin Clinical Trials

See Literature

Warfarin Note


Formerly known under the brand name Coumadin.

Warfarin Patient Counseling

See Literature