title: Pharmacogenetics-based coumarin therapy.
abstract: To reduce the risk of hemorrhage, experts advocate prescribing the anticipated therapeutic dose to patients who are beginning coumarin therapy, but until now there was no accurate way to estimate that dose. Using pharmacogenetics-based coumarin therapy, clinicians can now estimate the therapeutic dose by genotyping their patients for single nucleotide polymorphisms (SNPs) that affect coumarin metabolism or sensitivity. SNPs in the cytochrome P450 complex (CYP2C9) affect coumarin metabolism. Patients with either of two common variants, CYP2C9*2 or CYP2C9*3, metabolize coumarins slowly and are twice as likely to have a laboratory or clinical adverse event, unless their initial coumarin doses are reduced. SNPs in vitamin K epoxide reductase (VKORC1) correlate with coumarin sensitivity. Patients known to be homozygous for a common VKORC1 promoter polymorphism, -1639 G>A (also designated as VKOR 3673, haplotype A, or haplotype*2), should be started on lower coumarin doses than genotype GG patients. By providing an estimate of the therapeutic coumarin dose, pharmacogenetics-based therapy may improve the safety and effectiveness of coumarin therapy.
authors.affiliation: Washington University School of Medicine, St. Louis, MO 63110, USA. bgage@wustl.edu
authors.forename: Brian F
authors.initials: BF
authors.lastname: Gage
mesh_terms: D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics; D003374:Coumarins / Q000008:administration & dosage* / Q000378:metabolism; D065729:Cytochrome P-450 CYP2C9; D005838:Genotype; D006801:Humans; D006899:Mixed Function Oxygenases / Q000235:genetics; D010597:Pharmacogenetics; D020641:Polymorphism, Single Nucleotide / Q000502:physiology*; D064417:Vitamin K Epoxide Reductases
chemical_list: D003374:Coumarins; C030123:coumarin; D006899:Mixed Function Oxygenases; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases; C578523:VKORC1 protein, human; D064417:Vitamin K Epoxide Reductases