A case of intolerance to warfarin dosing in an intermediate metabolizer of CYP2C9.
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.
Lee
Soo-Youn
SY
Department of Laboratory Medicine, Samsung Medical Center, #50, Ilwon-dong, Kangnam-gu, Seoul 135-710, Korea.
Kim
June Soo
JS
Kim
Jong-Won
JW
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
D000925:Anticoagulants; D014859:Warfarin; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D001189:Aryl Hydrocarbon Hydroxylases