Racial and Ethnic Differences in Warfarin Response |
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Background and aim of the study: Variability
of drug response among individuals is a well-recognized problem that
may result in either under- or over-treatment of patients receiving similar
drug concentrations. Patients with mechanical heart valves are dependent
on adequate anticoagulation to prevent thrombosis development. ‘Crystalline
warfarin sodium’ (warfarin) is the most common antithrombotic drug
prescribed to control blood hemostasis in those patients, and also in
those with indications such as stroke, myocardial infarction, pulmonary
embolism and atrial fibrillation. Warfarin is a narrow therapeutic index
agent; a small change in systemic concentration of the drug may lead
to significant changes in pharmacodynamic response. Careful clinical
management is required to balance the risks of bleeding (over-anticoagulation)
with those of thrombosis (under-anticoagulation). The study aim was to
summarize environmental, genetic and ethnic factors that affect a patient’s
response to warfarin and which must be considered for optimal patient
outcome. |
summarize various factors that influence a patient’s
response to warfarin. Results: Inter-ethnic differences may have profound implications for the efficacy and safety of warfarin. Ethnic differences can affect pharmacokinetic features such as bioavailability, protein binding and volume of distribution, as well as hepatic metabolism and renal elimination. Environmental factors and genetic variants in human enzymes that metabolize warfarin also contribute to interindividual variations and may render some patients more susceptible to serious or life-threatening adverse events. Conclusion: Warfarin use is complicated by an unpredictable dose response that depends on factors such as demographics, diet, interacting drugs, genetic polymorphism and ethnic differences. The impact of racial differences on the kinetics of dose response or on drug efficacy is not well defined, as few clinical trials take ethnic variation into account. The use of the point of care and frequent patient self-testing may permit standardized warfarin monitoring across diverse geographical regions and facilitate analysis of ethnic variation among subpopulations. |
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