Warfarin (Coumadin) is the most commonly administered anticoagulant.
This medication interferes with normal blood clotting mechanisms by reducing
certain circulating blood proteins, which normally act to form blood clots.
Warfarin may be used in patients with atrial fibrillation (a cardiac arrhythmia)
to prevent stroke or embolism.
Warfarin may be given to patients with vein thrombosis (DVT, phlebitis)
and in pulmonary embolism, which is a condition where blood clots travel
from the veins in the legs to the lungs producing chest pain. Warfarin
is also administered when blood clots form in the heart after a heart
attack. On occasional Warfarin is also recommended in patients with severe
blockages of coronary arteries.
While taking Warfarin the patient is at increased risk of bleeding. It
is therefore necessary to monitor by a blood test called the prothrombin
time, often referred to as PT. The PT is standardized between laboratories
and reported as the INR (International Normalized Ratio). The INR is maintained
between 2 and 3 to prevent clotting in atrial fibrillation, phlebitis
and other conditions. With mechanical heart valves the INR is maintained
between 2.5 and 3.5. The INR should be maintained within a narrow range
in order to ensure that the blood is neither too thin nor too thick. Excessive
thinning of the blood can lead to bleeding. Based on INR determinations,
your physician should advise you as to your dose of Warfarin you should
be taking. Often the dose of warfarin is not stable and may have to be
adjusted frequently to keep the INR in the therapeutic range. .
Take a missed dose of Warfarin within eight hours but never take a double
dose to make up for the missed dose. Be aware that you have a risk of
bleeding. Being careful can reduce this risk. Never walk about barefoot,
use an electric razor for shaving, use a soft toothbrush, and wear gloves
to protect your hands when doing heavy work. Limit alcohol consumption
There are many drugs, which interact with Warfarin and alter its effect.
While taking Warfarin, do not take any new medications without the advice
and knowledge of your physician.