Coumarins and indandiones

Warfarin, the only drug listed here in this category, is a coumarin. It is an oral anticoagulant that inhibits Vitamin K epoxide reductase, an enzyme that that recycles oxidized vitamin K. Vitamin K is an activator of coagulating factors II, VII, IX and X, so by decreasing the availability of Vitamin K synthesis of these factors are decreased.

Warfarin is an extremely effective anticoagulant but there are a few drawbacks. It can interact with certain foods and can it cause serious interactions with many commonly used medicines. Regular blood monitoring (international normalized ratio-INR) is done to check for effectiveness and safety.

Warfarin is used to treat blood clots in cases of deep vein thrombosis or pulmonary embolism. It is also used to prevent thrombosis in patients at high risk, such as in atrial fibrillation, heart attack and knee or hip surgeries.