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Warfarin Sensitivity Genotyping



Summary of Polymorphisms and Warfarin Pharmacokinetics5

Slide 12

August 2008

This is a summary of the pharmacokinetics caused by the polymorphisms in the CYP2C9 gene. Both polymorphisms decrease the clearance of warfarin in the body, S-warfarin and because of this there is a concomitant increase in the half-life of warfarin in the body. So while the half-life for elimination of warfarin in a normal individual with no polymorphisms may be around 10 hours, it increases to roughly 32 hours in individuals with a single *2 polymorphism, and increases to 110 hours approximately in those individuals who have a single *3 polymorphism.

What this means is that while the studies state time may be two days in a normal individual it increases to nearly a week in an individual with a *2 allele and up to 23 days in an individual with a single *3 allele. So these polymorphisms decrease warfarin metabolism and intrinsic clearance, they increase the half-life and prolong time to steady state. There are other polymorphisms and alleles that are found in the CYP2C9 gene that affect the CYP2C9 protein but these are found less frequently and less is known about how these alleles actually impact the warfarin pharmacokinetics.

Summary of Polymorphisms

 


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