Flocoumafen is a second generation anticoagulant

Anticoagulant

An anticoagulant is a substance that prevents coagulation of blood. A group of pharmaceuticals called anticoagulants can be used in vivo as a medication for thrombotic disorders. Some anticoagulants are used in medical equipment, such as test tubes, blood transfusion bags, and renal dialysis...

 used as a rodenticide. It has a very high toxicity and is restricted to indoor use and sewers (in the UK). This restriction is mainly due to the increased risk to non-target species. Studies have shown that rodents resistant to first generation anticoagulants, can be adequately controlled with Flocoumafen.