Active bleeding requires emergent treatment.2 mg/kg can produce a significant increase in INR within 72 hours.Patients not on warfarin who have an acute ingestion:.Patient on therapeutic warfarin have significant risk of haemorrhage, for each unit rise in INR there is a 3.5x fold risk of bleeding.Prothrombin concentrate complex (25 – 50 IU/kg).Fresh frozen plasma (10 – 15 ml/kg) if prothrombin concentrate complex is not available.Uncontrolled or life threatening haemorrhage:.Warfarin and its metabolites are excreted in urine and faeces with an elimination half life of 35 hours.Hepatic metabolism and enterohepatic recirculation.Completely absorbed following oral administration.The half life of the coagulation factors are 6, 24, 40 and 60 hours (VII, IX, X and II, respectively) and hence it takes 12 hours for any effect of warfarin to become recordable. Vitamin K which is a cofactor for the synthesis of clotting factors II, VII, IX and X (plus protein C and S), warfarin inhibits Vitamin K. In 1941 Karl Paul Link gave him his answer and the rodent killer was born. He wanted to know what had killed his cow. In his truck, he had also brought a dead heifer and some spoiled clover hay.

In 1933 a farmer from Deer Park showed up unannounced at the School of Agriculture and walked into a professor’s laboratory with a milk can full of blood which would not coagulate.

On a trivia note warfarin was invented with the help of the Wisconsin Alumni Research Foundation (WARF) and hence the origin of the name (-arin indicating the link with coumarin). This can make the approach to treatment difficult when considering the need for therapeutic anticoagulation and expert advice maybe required. Over anticoagulation is a common problem with warfarin and acute intoxication maybe in those with or without an anticoagulation requirement.

Antidote warfarin