General Information

What is warfarin?

Warfarin is an anticoagulant; used to prevent blood clots from forming or growing larger in your blood and blood vessels. Often referred to the misnomer “blood thinner”, anticoagulants, such as warfarin (or brand of warfarin such as Coumadin®), help to prevent clots from forming in the blood by decreasing the clotting ability of the blood.

These medications are long-acting oral anticoagulants with a “long half-life”. The “half-life” is the time required for the amount of the drug in the blood to half of its original value, measured in days. Warfarin half-life allows for some flexibility in dosing and provides a safety margin since changes occur very slowly.

Warfarin Background

According to the Agency for Healthcare Research and Quality, warfarin was first discovered in 1933 after cattle in Canada and the Northern Plains of America began dying of internal bleeding. After a Wisconsin farmer brought this phenomenon to the attention of Professor Karl Paul Link at the University of Wisconsin, they isolated the anticoagulant in the cattle's feed.

The cattle had grazed on sweet clover hay and the bleeding occurred most frequently when the climate, and therefore the hay, in these areas were damp. Link and his team found that the natural coumarin became oxidised in the moldy hay, to form dicumarol. Further research in 1950's resulted in using warfarin in humans, patented as Coumadin®. Widespread use did not occur until warfarin was used to treat President Dwight D. Eisenhower after a heart attack.