Race and ethnicity effects on Warfarin
Bethany Miller March 3, 2022
Warfarin is a commonly used anticoagulant therapy worldwide and is often prescribed to treat and prevent various blood clotting events or disorders. Due to its narrow therapeutic index, it is critical to ensure that a patient is on the correct warfarin dose – too high of a dose increases the patient’s bleed risk, while too low of a dose leaves the patient susceptible to experiencing a blood clot.
However, due to high variability in how individual patients respond to warfarin, it can be challenging to obtain the correct dose without the need for heavy monitoring and multiple blood draws.  


One reason for this high interpatient variability in warfarin response is due to genetics – CYP2C9 is a liver enzyme that is responsible for metabolizing warfarin in the body. If a patient has decreased CYP2C9 function, then they may be at an increased risk of warfarin-associated bleed, due to the drug not being cleared from the body at a quick enough rate.
These patients, known as CYP2C9 Intermediate Metabolizers or CYP2C9 Poor Metabolizers, typically require a lower dose of warfarin to maintain a proper anticoagulant effect and to prevent unwanted bleeding.  


A number of CYP2C9 reduced function alleles are found almost exclusively in patients with African ancestry – specifically, CYP2C9*5, *6, *8, and *11. Patients who carry either one or two of these alleles are considered to be CYP2C9 Intermediate or Poor metabolizers, and therefore will be recommended to take warfarin at a lower dose.  


While utilizing pharmacogenetics testing for warfarin dosing guidance, it is critical to test for the appropriate markers for these CYP2C9 alleles commonly found in African and African American patients in order to provide appropriate and inclusive therapeutic care.  



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Located in Chicago, BASE10 is a healthcare software technology company whose platform creates turnkey disease management programs that can be deployed at scale for nursing home operators, pharmacies, payors, and self-funded employers.


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