Figure 1.

Warfarin interactive pathways. Warfarin R- and S- enantiomers are metabolized by different CYP enzymes and affect the coagulation cascade by inhibiting the vitamin K epoxide reductase complex 1 (VKORC1), preventing the carboxylation of clotting factors II, VII, IX and X. S-warfarin is the more potent enantiomer, as indicated by the thicker arrow. The influence of polymorphisms in the genes encoding CYP2C9, VKORC1, EPXH1, APOE, GGCX, CALU, CYP4F2 and factor VII on warfarin dose requirements is discussed in the text