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Warfarin sensitivity: be aware of genetic influence
Tayyaba Khan1, Farhad Kamali, Ann Daly
1Department of Pharmacological Sciences, University of Newcastle upon Tyne, Newcastle Upon Tyne NE1 4LP, UK.
Age and Ageing
|March 5, 2003
Summary
Warfarin therapy can cause over-anticoagulation and bleeding. Identifying patients with variant CYP2C9 alleles before treatment can help avoid adverse outcomes.
Area of Science:
- Pharmacogenomics
- Drug Metabolism
- Clinical Pharmacology
Background:
- Warfarin is a common anticoagulant used to treat venous thromboembolism.
- Over-anticoagulation with warfarin increases the risk of bleeding complications.
- Individual patient response to warfarin can vary significantly.
Observation:
- Two elderly patients with venous thromboembolism showed an extreme anticoagulant response to warfarin.
- These patients were found to possess variant alleles of the CYP2C9 gene.
- CYP2C9 is crucial for metabolizing warfarin, and variant alleles impair this function.
Findings:
- Variant CYP2C9 alleles are associated with reduced warfarin metabolism.
- This reduced metabolism leads to higher warfarin levels and an exaggerated anticoagulant effect.
- The observed extreme response in these patients is directly linked to their CYP2C9 genotype.
Implications:
- Genetic screening for CYP2C9 variants can predict warfarin response.
- Identifying patients with variant alleles before warfarin initiation can guide dosing.
- Personalized warfarin therapy based on pharmacogenomics can improve safety and efficacy, reducing bleeding risk.