Blood Coagulation
Mechanism of Action
Side Effects
The Future


Anticoagulants are medications that delay the coagulation of blood. They are sometimes referred to as "blood thinners". Some anticoagulants in use are acenocoumarol, dicoumarol, heparin and warfarin.

Warfarin is probably the best known and most widely used oral anticoagulant. It is a non-habit forming medication used to limit the size of existing blood clots  and to prevent formation of new blood clots in high-risk patients.

Two chemical names for warfarin are
  • 4-Hydroxy-3-(3-oxo-1-phenyl-butyl)-chromen-2-one and
  • 3-(2-acetyl-1-phenylethyl)-4-hydroxycoumarin

and its chemical structure is shown below.

       Structure in the crystalline form
Chemical structure
As observed from its structure, warfarin exists as a pair of chiral enantiomers. It  is marketed as a racemic mixture of its sodium salt under the brand names Coumadin® (USA) and Marevan® (UK) and as its generic version Warfarin Sodium. The salt is very soluble in water and freely soluble in alcohol. Coumadin®  is sold as coloured tablets, each colour indicating the strength of the dose.


generic warfarin

Another  large application of warfarin is as rat poison, or, more technically, as a rodenticide. It is very effective in controlling  Norway (Brown) rats and house mice. As rat poison, it comes in water-soluble, ready-to-use bait, concentrate, powder, liquid concentrate , nylon pouch and dust formulations.

Warfarin has found very ready acceptance because rodents do not tend to become bait shy after once testing the material. They continue to consume it until its anticlotting properties have produced death through internal haemorrhaging.

The amount of warfarin that is lethal to 50% of experimental animals fed the material is referred to as its acute oral lethal dose fifty, or LD50. The acute oral toxicity  in rats is  reported to be 58 mg/Kg in female rats. The LD50 for rats over 4-5 days is 1 mg/Kg/day.

brown rat

Brown Rat ( Rattus Norvegicus)