Warfarin

Vitamin K antagonists (VKA) are a class of anticoagulants which , as their name indicates act by inhibiting the action of vitamin K, coumarins are the most commonly used VKA. In medicine the most commonly used VKA is warfarin.. Warfarin is an antagonist of Vitamin K, a necessary element in the synthesis of clotting factors II, VII, IX, and X as well as the naturally occuring endogenous anticoagulatant protein C and S which are biologically inactive without the carboxylation of certain glutamic acid residues.