Warfarin use and dose adjustment in a patient with mitral valve replacement

Warfarin is an anticoagulant suppressing the synthesis of the specific vitamin K-dependent coagulation factors II, VII, IX and X as well as two vitamin K-dependent plasma proteins C and S. Warfarin therapy may bring about severe consequences including warfarin embryopathy associated with maternal warfarin ingestion, warfarin resistance, excessive anticoagulation and warfarin reversal. A 51-year-old female patient experienced warfarin resistance as well as subsequent excessive coagulation and warfarin reversal. With regulation of warfarin dosage and close monitoring of the international normalized ratio, she eventually obtained a proper target international normalized ratio with stable warfarin dose. The patient was more likely to have an acquired warfarin resistance. To regulate dietary habit might be a good solution for the resistance to this drug. In addition, individualized regimen for warfarin use should be established based on the conditions of individual patient including patient's age, gender, body surface area, dietary habit and target international normalized ratio, etc.