Warfarin is the main oral
anticoagulant used in the UK. Oral means it's taken by mouth. An anticoagulant
is a medicine that stops blood clotting. Clotting (thickening) is a complex process involving a number of
substances called clotting factors.
Clotting factors are produced by the liver and help control bleeding.
They work with cells that trigger the clotting process (platelets) to ensure
blood clots effectively. To produce some of the clotting factors, the liver needs a good supply
of vitamin K.
Warfarin blocks one of the enzymes (proteins) that uses vitamin K to
produce clotting factors. This disrupts the clotting process, making it take
longer for the blood to clot.