Ann Rehabil Med.  2012 Dec;36(6):857-860.

CYP2C9 Mutation Affecting the Individual Variability of Warfarin Dose Requirement

• Kim YB
• Ko MJ
• Lee DG
• Do JG
• Hwang JH

Abstract

Warfarin is a frequently prescribed anticoagulant in rehabilitation patients. Adverse drug reactions of warfarin were reported as bleeding and cutaneous microvascular thrombosis. Major bleeding, such as intracranial hemorrhage and psoas hematoma, in patients receiving anticoagulation therapy is a rare condition, but sometimes very serious complication that can even be fatal. Patient-specific factors (eg, age, body size, race, concurrent diseases, and medications) explain some of the individual variability in warfarin dose, but genetic factors, which influence warfarin response, explain a significantly higher proportion of the variability in the dose. There are two identified genes that are responsible for the main proportion of the genetic effect: CYP2C9, which codes for the enzyme cytochrome P450 2C9 that metabolizes S-warfarin, and VKORC1, which codes for warfarin's target, vitamin K epoxide reductase. We report a case of intolerance to warfarin dosing, due to impaired drug metabolism in a patient with CYP2C9*1/*3 and VKORC 1173TT. Fortunately, there are no severe complications.

Keyword

Warfarin; CYP2C9; Vitamin K epoxidase

MeSH Terms

Body Size
Continental Population Groups
Cytochrome P-450 Enzyme System
Drug Toxicity
Hematoma
Hemorrhage
Humans
Intracranial Hemorrhages
Mixed Function Oxygenases
Oxidoreductases
Thrombosis
Vitamin K
Warfarin
Cytochrome P-450 Enzyme System
Mixed Function Oxygenases
Oxidoreductases
Vitamin K
Warfarin

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