Warfarin
- OralWarfarinCoumadin, Marevan
Mechanism of Action
- Inhibits regeneration of vitamin K from vitamin K epoxide, resulting in reduced synthesis of clotting factors II, VII, IX and X, as well as proteins C and S.
- Pharmacology
- Delayed onset and initial procoagulant effect - bridging heparin / clexane should be used until warfarin is therapeutic.
- Reversed with vitamin K, fresh frozen plasma and prothrombinex.
Clinical Use
- Indications
- Treatment of venous thromboembolism (DVT / PE)
- Prosthetic heart valve (prevention of thromboembolism)
- Atrial fibrillation (prevention of stroke) - particularly valvular AF
- Large myocardial infarction
- Contraindications
- Active bleeding, or high risk of bleeding (risk / benefit analysis)
- Cancer-associated venous thromboembolism (enoxaparin / factor Xa inhibitors are superior)
- Pregnancy
- Adverse Effects
- Haemorrhage
- Skin necrosis
- Cholesterol microemboli
- Monitoring
- International normalised ratio (INR).
- AF / VTE - generally aim INR 2.0 - 3.0
- Prosthetic heart valve - generally aim INR 2.5 - 3.5
