Warfarin (Coumadin®,Jantoven®,Marfarin®)

Warfarin is used to prevent blood clots from forming or growing larger in your blood and blood vessels. It is prescribed for people with certain types of irregular heartbeat, people with prosthetic (replacement or mechanical) heart valves, and people who have suffered a heart attack. Warfarin is also used to treat or prevent venous thrombosis (swelling and blood clot in a vein) and pulmonary embolism (a blood clot in the lung). Warfarin is in a class of medications called anticoagulants ('blood thinners'). It works by decreasing the clotting ability of the blood.

How administered
Warfarin is an oral medication in pill form.  The dosage and administration of Warfarin must be individualized for each patient according to the particular patient's PT/INR response to the drug. The dosage should be adjusted based upon the patient's PT/INR

Risks/Side Effects
The most serious risks associated with anticoagulant therapy with Warfarin is hemorrhage in any tissue or organ

Call your doctor at once if you have any of these serious side effects:
  • skin changes or discoloration anywhere on your body;
  • purple toes or fingers;
  • pain in your stomach, back, or sides;
  • low fever, loss of appetite, dark urine, jaundice (yellowing of the skin or eyes);
  • diarrhea, fever, chills, body aches, flu symptoms;
  • easy bruising or bleeding that will not stop;
  • blood in your urine;
  • black, bloody, or tarry stools;
  • nosebleeds, bleeding gums, coughing up blood;
  • feeling weak or light-headed;
  • sudden headache, confusion, problems with vision, speech, or balance;
  • sudden leg or foot pain; or
  • sudden numbness or weakness, especially on one side of the body.

Less serious side effects may include:

  • nausea, vomiting, stomach pain;
  • gas and bloating; or
  • hair loss.

Warfarin acts by inhibiting the synthesis of vitamin K dependent clotting factors, which include Factors II, VII, IX and X, and the anticoagulant proteins C and S.  Vitamin K is an essential cofactor for the post ribosomal synthesis of the vitamin K dependent clotting factors. The vitamin promotes the biosynthesis of γ-carboxyglutamic acid residues in the proteins which are essential for biological activity.

The price of PT/INR monitoring is a factor that must be considered when determining the total cost of treatment.  Prices vary considerably.

Additional info
The traditional anticoagulants that have been in use for the prevention or treatment of thromboembolic disease are heparin, as well as it’s various analogues, and warfarin. There are two major drawbacks to these medications: a narrow dosage range that provides adequate anticoagulation without bleeding, and a highly individualized response to various doses among individuals that requires fairly frequent monitoring by laboratory testing.

In recent years, several types of anticoagulants and antiplatelets have been developed or studied to help overcome these drawbacks.  Although few of these have been studied, and none have been FDA approved as conjunctive treatment for PH, your doctor still might prescribe them if he/she feels that they are a better option in your particular case.  We are providing links to more information on these medications here for your convenience.

The classes of anticoagulants include:
- Factor Xa inhibitors
- Direct thrombin inhibitors
       Bivalirudin (Angiomax)
       Dabigatran  (Pradaxa)

The classes of antiplatelet drugs include:
- Irreversible cyclooxygenase inhibitors
- Adenosine diphosphate (ADP) receptor inhibitors:
       Clopidogrel  (Plavix)
       Prasugrel  (Effient)
       Ticagrelor (Brilinta)
       Ticlopidine (Ticlid)
- Adenosine reuptake inhibitors
       Dipyridamole (Persantine)
- Phosphodiesterase inhibitors
       Cilostazol (Pletal)
- Glycoprotein IIB/IIIA inhibitors
       Abciximab (ReoPro)
       Eptifibatide (Integrilin)
       Tirofiban (Aggrastat)

Visit the FDA Page for this drug/therapy

Page Reviewed/Edited: June 2012

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