Oral Anticoagulants Flashcards
Only the ___________ derivatives are used in the U..S.
coumarin
What 2 reasons is coumadin used for?
1) prophylaxis of thrombosis
2) treatment of thrombus
warfarin decreases the functionality of coagulation factors ___ ___ ___ and ___
II, VII, IX, X
2, 7, 9, 10
_______ works primarily on the intrinsic pathway while ________ works primarily on the extrinsic pathway
heparins (intrinsic)
warfarin (extrinsic)
Warfarin is an analgue of _________
vitamin K
What is the mechanism of action of coumadin?
depress formation of factor 2, 7, 9, 10 by inhibiting carboxylation of glutamic acid (which is essential for Ca++ binding)
How does warfarin inhibit vitamin K?
blocks vitamin K reductase
True or false: coumadin is used first to anticoagulate patients in the hospital
FALSE; use heparin first because of fast onset of action then switch to oral anticoags when the patient is discharged
What is the order of factor decline after warfarin treatment?
7 = first to decrease then 9, 10, 2
Does coumadin have a long or short half life?
LONG (binds to plasma albumin)
How is warfarin metabolized?
hepatic ER
metabolism varies greatly in patients (depending on liver function)
What metric is used to monitor the anticoag effects of warfarin?
PT (since warfarin affects the extrinsic pathway)
What are the vitamin K dependent factors?
2, 7, 9, 10
a _____ prolongation of the PT from baseline is considered to be therapeutic
1.5x
What is the INR?
international normalized ratio (PT of patient/PT of mean normal control)
What is the INR used for?
to universally adjust the level of anticoag used for patient
Why can you not eat leafy greens on warfarin?
because warfarin INHIBITS vitamin K synthesis, if you are eating it, that inhibition is overridden
What are 5 factors that affect warfarin dosage?
1) nutrition
2) anemia
3) liver disease
4) biliary obstruction
5) drugs
Our normal source of vitamin K is __________
gut flora
decrease normal flora with antibiotics, get decrease in vitamin K
The principal toxicity of warfarin is ____________________
hypoprothrombinemia (resulting in ecchymoses, purpura, hematuria, hemorrhage)
Can pregnant moms take warfarin?
NO NO NO
all oral anticoagulants pass the placental barrier and can cause fetal malformation
How and why is coumadin associated with necrosis?
impairment of functionality of protein C (requires gamma carboxylation of glutamic acid)
What is the antidote to warfarin toxicity?
vitamin K
or infusion of plasma, recombinant factor VIIa
What role does vitamin K play in coagulation?
required for the synthesis of clottable coag factors (2, 7, 9, 10)
Why do newborns get an injection of vitamin K right after they are born?
ALL newborns are born with hypoprothrombinemia (do not get coag factors 2, 7, 9, 19)
What are the 2 oral anti-Xa agents?
1) rivaroxaban (xarelto)
2) apixiban
What is the oral antithrombin (anti-IIa) agent?
dabigatran
