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Warfarin

Class
Anticoagulants
Subclass
Vitamin K antagonists
Generic name
Warfarin sodium
Brand names
Coumadin®, Jantoven®
Common formulations
Tablet
Dosage and administration
Adults patients
Treatment
DVT
•
Start at: 2-5 mg PO daily
•
Maintenance: 2-10 mg PO daily for ≥ 3 months, adjusted to target an INR of 2-3
PE
•
2-10 mg PO daily ≥ 3 months
Prevention
Prevention of thromboembolism in patients with AF
•
2-10 mg PO daily
Other off-label uses
•
Treatment of thromboembolism in patients with antiphospholipid syndrome
•
Prevention of thromboembolism, after cardiac valve replacement
Indications for use
Labeled indications
Adults
•
Treatment of DVT
•
Treatment of PE
•
Treatment of VTE
•
Prevention of DVT
•
Prevention of stroke in patients with CVD
•
Prevention of thromboembolism in patients with AF
•
Prevention of thromboembolism, after cardiac valve replacement
•
Secondary prevention of cardiovascular mortality in patients with myocardial infarction
•
Secondary prevention of DVT
•
Secondary prevention of PE
Off-label indications
Adults
•
Treatment of thromboembolism in patients with antiphospholipid syndrome
•
Prevention of thromboembolism, after cardiac valve replacement
Safety risks
Boxed warnings
Bleeding tendency
•
Monitor INR regularly Instruct patients about prevention measures to minimize risk of bleeding and to report signs and symptoms of bleeding
Contraindications
Hypersensitivity to warfarin or any of its components
Conditions, such as; hemorrhagic tendencies or blood dyscrasias, recent or contemplated surgery of the CNS or eye, or traumatic surgery resulting in large open surfaces, active ulceration or overt bleeding of the gastrointestinal, genitourinary, or respiratory tract, cerebral aneurysms, dissecting aorta, pericarditis and pericardial effusions, threatened abortion, eclampsia, and preeclampsia and malignant hypertension
Warnings and precautions
AKI
•
Use caution in patients with a history of kidney disease.
Bleeding tendency
•
Use caution in patients with Vitamin C or K deficiency.
Calciphylaxis
•
Use caution in patients with and without ESRD.
Hematoma, bleeding
•
Use caution in patients receiving intramuscular injections of other drugs.
Maculopapular rash
•
Use caution in patients with a history of coumarin anticoagulants hypersensitivity.
Tissue necrosis
•
Use extreme caution in patients with diabetes mellitus, peripheral arterial disease or atherosclerosis, recent trauma or surgery, improper dosing of warfarin, and protein C and S deficiency.
Warfarin-induced skin necrosis, lower extremity amputation, purple-toe syndrome
•
Use extreme caution in patients with immune thrombocytopenic purpura, heparin-induced thrombocytopenia and DVT.
Specific populations
Renal impairment
eGFR 0-90 mL/min/1.73 m²
•
Use acceptable. No dose adjustment required.
Renal replacement therapy
Any modality
•
Use acceptable. No dose adjustment required.
Hepatic impairment
Any severity
•
Use with caution. - Weigh risks versus benefits of anticoagulant therapy in patients with moderate to severe hepatic impairment.
Pregnancy and breastfeeding
Pregnancy
All trimesters • Australia Category: D
•
Avoid use. Evidence of fetal harm in humans. Pregnant women with mechanical heart valves: Warfarin sodium may cause fetal harm; however, the benefits may outweigh the risks.
Breastfeeding
Use with caution during breastfeeding.
•
Monitor infants for bruising and bleeding.
Undetectable in breastmilk.
Unknown drug levels in breastfed infants.
Unlikely to cause adverse effects in breastfed infants.
Adverse reactions
Very common > 10%
•
Bleeding, ocular hemorrhage
Uncommon < 1%
•
Intracranial hemorrhage, tissue necrosis
Unknown frequency
•
Alopecia, anemia, bone fracture, calciphylaxis, coma, dysgeusia, ecchymosis, exfoliative dermatitis, gastrointestinal bleeding, hepatitis, hypotension, ↑ liver enzymes, jaundice, lethargy, maculopapular rash, pallor, petechiae, purple-toe syndrome, angina pectoris, asthenia, chest pain, chills, diarrhea, dizziness, fatigue, fever, flatulence, headache, hematuria, itching, malaise, nausea, nosebleed, paresthesia, priapism, syncope, vaginal bleeding, vomiting, retroperitoneal hemorrhage, teratogenesis, urticaria
Interactions
Drug(s)
Check Interactions
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