Warfarin sodium, also known as Coumadin®, Jantoven®, or Marfarin®, belongs to a group of medications known as anticoagulants. Anticoagulant therapy using Coumadin® is usually highly individualized from patient to patient. Physicians commonly prescribe warfarin for medical conditions that may contribute to blood clot formation.
Clotting factors II, VII, IX, and X, along with proteins C and S require vitamin K for synthesis. The precursors of these factors involve the joining of carboxyl groups with glutamic acid. This combination allows blood cells to adhere to the surfaces of blood vessel walls but only occurs in the presence of activated vitamin K. The anticoagulant effect of warfarin sodium prevents vitamin K from activating the combination.
Each dose of warfarin sodium diminishes the amount of activated vitamin K by 30% to 50%. The process begins after the first dose, but the medication does not reach peak blood levels for 72 to 96 hours. As each patient responds to therapy differently, physicians usually closely monitor the medication’s effectiveness by performing routine lab tests. The test commonly used for this assessment determines the prothrombin time and international ratio (PT/INR), which indicates the number of seconds required for the blood to clot.
Physicains prefer specific clotting times for certain medical circumstances, but generally prescribe warfarin sodium using the PT/INR as a guideline. Asians and older adults exhibit a greater sensitivity to warfarin and typically respond to therapy faster than other patients. They may not need as high a dose as other patients.
Warfarin sodium may be prescribed for patients who are risk of developing deep vein thrombosis or those who have suffered a heart attack, irregular heartbeat, or stroke. It is also frequently prescribed for patients receiving prosthetic heart valves. These patients exhibit physiological conditions that may contribute to blood pooling and clot formation.
Patients should not combine warfarin sodium with other medications or substances, including alcohol, that have anticoagulant properties, unless directed by a physician. They should exercise caution in daily activities, as any bleeding will stop less quickly. The medication may also cause the release of atherosclerotic plaques and fatty emboli. Under these circumstances, patients may experience sudden sharp pains in the limbs or other regions of the body or exhibit a condition known as purple toes.
