THERAPEUTICS

Brands

• Coumadin, Jantoven, Carfin, Marevan, Panwarfin, Warx

Generic?

• Yes

Class

• Anticoagulant

Commonly Prescribed for

(FDA approved in bold)

• Prophylaxis and treatment of venous thrombosis and pulmonary embolism

• Prophylaxis and treatment of thromboembolic complications associated with atrial fibrillation (AF) and/or cardiac valve replacement

• Reduction in the risk of death, recurrent myocardial infarction (MI), and thromboembolic events such as stroke or systemic embolization after MI

• Cerebral venous sinus thrombosis

• Arterial dissection

How the Drug Works

• Interferes with the synthesis of vitamin K-dependent clotting factors II, VII, IX, X and anticoagulant proteins C and S as well as vitamin K epoxide reductase (VKORC1) enzyme complex. It decreases risk of thromboembolism

How Long Until It Works

• Anticoagulant effect is delayed for up to 5–7 days due to the long half-lives of factors II, IX, and X. Heparin is preferred for rapid anticoagulation

If It Works

• Continue to use with appropriate monitoring of PT/INR. Early elevation of PT does not reflect anticoagulation

If It Doesn't Work

• Patients can still have stroke despite treatment. Warfarin is only superior to antiplatelet agents for cardiogenic stroke, i.e., related to AF or ventricular thrombus. Control all stroke risk factors, such as smoking, hyperlipidemia, and hypertension. For acute events, admit patients for treatment and diagnostic testing. Check INR to determine drug effectiveness

Best Augmenting Combos for Partial Response or Treatment-Resistance

• The combination of oral anticoagulants and antiplatelets is not recommended for recent stroke/transient ischemic attack (TIA) but reasonable in acute coronary syndrome or stent placement (Class IIb, Level of Evidence C)

• For patients with rheumatic mitral valve disease who have stroke/TIA while being treated with adequate warfarin, the addition of aspirin might be considered (Class IIb; Level of Evidence C)

• For patients with a mechanical mitral or aortic valve who have a history of ischemic stroke or TIA before its insertion and who are at low risk for bleeding, the addition of aspirin 75–100mg/day to warfarin is recommended (Class I; Level of Evidence B)

Tests

• Monitor PT/INR to determine effectiveness