Warfarin works by inhibiting the reductase enzyme (gamma-glutamyl carboxylase) that converts Vitamin K into its active form. Clotting factors II, VII, IX and X are Vitamin K dependent and are thus decreased with warfarin use.
However, protein C and S are also Vitamin K dependent. These 2 proteins break down factor Va and factor VIIIa which are critical in the clotting pathways. With decreased levels of protein C and S, factors Va and VIIIa are not broken down, thus resulting in a procoagulant effect initially.
The full anti-thrombotic effect of warfarin kicks in only after levels of factor II significantly reduce days later.
However, protein C and S are also Vitamin K dependent. These 2 proteins break down factor Va and factor VIIIa which are critical in the clotting pathways. With decreased levels of protein C and S, factors Va and VIIIa are not broken down, thus resulting in a procoagulant effect initially.
The full anti-thrombotic effect of warfarin kicks in only after levels of factor II significantly reduce days later.