Oral Anticoagulants

Question 1

Only the ___________ derivatives are used in the U..S.

Answer 1

coumarin

Question 2

What 2 reasons is coumadin used for?

Answer 2

1) prophylaxis of thrombosis

2) treatment of thrombus

Question 3

warfarin decreases the functionality of coagulation factors ___ ___ ___ and ___

Answer 3

II, VII, IX, X

2, 7, 9, 10

Question 4

_______ works primarily on the intrinsic pathway while ________ works primarily on the extrinsic pathway

Answer 4

heparins (intrinsic)

warfarin (extrinsic)

Question 5

Warfarin is an analgue of _________

Answer 5

vitamin K

Question 6

What is the mechanism of action of coumadin?

Answer 6

depress formation of factor 2, 7, 9, 10 by inhibiting carboxylation of glutamic acid (which is essential for Ca++ binding)

Question 7

How does warfarin inhibit vitamin K?

Answer 7

blocks vitamin K reductase

Question 8

True or false: coumadin is used first to anticoagulate patients in the hospital

Answer 8

FALSE; use heparin first because of fast onset of action then switch to oral anticoags when the patient is discharged

Question 9

What is the order of factor decline after warfarin treatment?

Answer 9

7 = first to decrease then 9, 10, 2

Question 10

Does coumadin have a long or short half life?

Answer 10

LONG (binds to plasma albumin)

Question 11

How is warfarin metabolized?

Answer 11

hepatic ER

metabolism varies greatly in patients (depending on liver function)

Question 12

What metric is used to monitor the anticoag effects of warfarin?

Answer 12

PT (since warfarin affects the extrinsic pathway)

Question 13

What are the vitamin K dependent factors?

Answer 13

2, 7, 9, 10

Question 14

a _____ prolongation of the PT from baseline is considered to be therapeutic

Answer 14

1.5x

Question 15

What is the INR?

Answer 15

international normalized ratio (PT of patient/PT of mean normal control)

Question 16

What is the INR used for?

Answer 16

to universally adjust the level of anticoag used for patient

Question 17

Why can you not eat leafy greens on warfarin?

Answer 17

because warfarin INHIBITS vitamin K synthesis, if you are eating it, that inhibition is overridden

Question 18

What are 5 factors that affect warfarin dosage?

Answer 18

1) nutrition
2) anemia
3) liver disease
4) biliary obstruction
5) drugs

Question 19

Our normal source of vitamin K is __________

Answer 19

gut flora

decrease normal flora with antibiotics, get decrease in vitamin K

Question 20

The principal toxicity of warfarin is ____________________

Answer 20

hypoprothrombinemia (resulting in ecchymoses, purpura, hematuria, hemorrhage)

Question 21

Can pregnant moms take warfarin?

Answer 21

NO NO NO

all oral anticoagulants pass the placental barrier and can cause fetal malformation

Question 22

How and why is coumadin associated with necrosis?

Answer 22

impairment of functionality of protein C (requires gamma carboxylation of glutamic acid)

Question 23

What is the antidote to warfarin toxicity?

Answer 23

vitamin K

or infusion of plasma, recombinant factor VIIa

Question 24

What role does vitamin K play in coagulation?

Answer 24

required for the synthesis of clottable coag factors (2, 7, 9, 10)

Question 25

Why do newborns get an injection of vitamin K right after they are born?

Answer 25

ALL newborns are born with hypoprothrombinemia (do not get coag factors 2, 7, 9, 19)

Question 26

What are the 2 oral anti-Xa agents?

Answer 26

1) rivaroxaban (xarelto)

2) apixiban

Question 27

What is the oral antithrombin (anti-IIa) agent?

Answer 27

dabigatran