Warfarin is used for preventing and treating venous or arterial thrombosis and embolism.

Warfarin works by blocking the gamma-carboxylation of glutamic acid residues of Vitamin K−dependent coagulation factors. This blockage inhibits synthesis of Vitamin K−dependent coagulation factors, resulting in decreased biological activity of factors II, VII, IX, X and protein C and protein S; with prolongation of the international normalised ratio (INR).

Warfarin is a potentially hazardous drug that causes major bleeding, including intracranial haemorrhage. Patients on long-term therapy have a risk of 1%-3% per year for haemorrhage leading to hospitalisation or death.(1)

Recently, the PBS has provided subsidy to new oral anticoagulants (NOAC) which may be used alternatively to warfarin.

  1. Tadros Rami, Shakib, Sepehr.  Warfarin indications, risks and drug interactions.  AFP 2010; 39(7):476-479.