warfarin

Question 0

vitamin K dependent proteins

Answer 0

factors II, VII, IX, X

Question 1

warfarin

Answer 1

Warfarin, a coumarin derivative, produces an anticoagulant effect by interfering with the cyclic interconversion of vita-min K and its 2,3 epoxide (vitamin K epoxide). Vitamin K is a cofactor for the carboxylation of glutamate residues to � -carboxyglutamates (Gla) on the N-terminal regions of vitamin K–dependent proteins

Question 2

warfarin
maximal blood concentration in __ mins
half-life

Answer 2

90 mins

36-42 hrs

Question 3

why is overlap with heparin necessary when starting anticoagulation with warfarin

Answer 3

Because the half-life of prothrombin or factor II is 60 to 72 hours, >4 days’ overlap is necessary

Question 4

management of elevated INrs

Answer 4

There is a close relation between the INR and risk of bleeding (Table 1). The risk of bleeding increases when the INR exceeds 4, and the risk rises sharply with values �5. Three approaches can be taken to lower an elevated INR. The first step is to stop warfarin; the second is to administer vitamin K1; and the third and most rapidly effective measure is to infuse fresh plasma or prothrombin concentrate.