title: A case of intolerance to warfarin dosing in an intermediate metabolizer of CYP2C9.
abstract: We report a case of intolerance to warfarin dosing due to impaired drug metabolism in a patient heterozygous for the CYP2C9*3 allele. A 30-year-old woman with an artificial cardiac pacemaker was taking warfarin to prevent thromboembolism. This patient had an extremely elevated international normalized ratio (INR) of prothrombin time (PT) following standard doses of warfarin and experienced difficulties during the induction of anticoagulation. Genotyping for CYP2C9 revealed that this patient was an intermediate metabolizer with genotype CYP2C9*1/*3. This case suggests the clinical usefulness of pharmacogenetic testing for individualized dosage adjustments of warfarin.
authors.affiliation: Department of Laboratory Medicine, Samsung Medical Center, #50, Ilwon-dong, Kangnam-gu, Seoul 135-710, Korea.
authors.forename: Soo-Youn
authors.initials: SY
authors.lastname: Lee
authors.forename: June Soo
authors.initials: JS
authors.lastname: Kim
authors.forename: Jong-Won
authors.initials: JW
authors.lastname: Kim
mesh_terms: D000328:Adult; D000925:Anticoagulants / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism; D001189:Aryl Hydrocarbon Hydroxylases / Q000235:genetics* / Q000378:metabolism; D065729:Cytochrome P-450 CYP2C9; D004252:DNA Mutational Analysis; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D011110:Polymorphism, Genetic; D011517:Prothrombin Time; D014859:Warfarin / Q000008:administration & dosage / Q000009:adverse effects* / Q000378:metabolism
chemical_list: D000925:Anticoagulants; D014859:Warfarin; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases