Anticoagulant Quiz

Question 1

Match the correct response.

Warfarin
This clotting factor has the shortest half life
Reverses warfarin
Heparin

Factor VII
The aPTT is used to measure the intensity of pharmacologic effect
The normalized prothrombin time is used to measure the intensity of pharmacologic effect
Phytonadione

Answer 1

Warfarin: The normalized prothrombin time is used to measure the intensity of pharmacologic effect
This clotting factor has the shortest half life: Factor VII
Reverses warfarin: Phytonadione
Heparin: The normalized aPTT is used to measure the intensity of pharmacologic effect

Question 2

Which statement about warfarin is correct?

A) Foods containing large amounts of vitamin K can antagonize warfarin
B) Warfarin exerts its effect on coagulation through the activation of antithrombin III
C) Patients should stop eating fruits and veggies when treated with warfarin
D) Warfarin has an immediate effect on coagulation

Answer 2

A
(B = heparin)

Question 3

Match the medication with the MOA:

Heparin
Warfarin
Dabigatran (Pradaxa)
Rivaroxaban (Eliquis)

Factor Xa inhibitor
Activates antithrombin III
A vitamin K antagonist
Direct thrombin inhibitor

Answer 3

Heparin: activates antithrombin III
Warfarin: a vitamin K antagonist
Dabigatran: direct thrombin inhibitor
Rivaroxaban: factor Xa inhibitor

Question 4

This question reviews your understanding of principles of pharmacology as applied to anticoagulant medication.

Your patient is responding well to warfarin and is stabilized for a month with a consistent INR of 2.2. Drug B is added but everything else stays the same. After starting on Drug B the INR falls and after two weeks stabilizes to 1.6. Drug B is stopped and Drug C is started. the INR increases but after 4 weeks stabilizes at 2.8.

One of the following explanations listed below correctly explains this observation. Which statement is correct?

This question is straight forward and fairly easy. Think through each possible explanation and the correct answer should be clear.

A) Drug B displaces warfarin from plasma binding proteins. Drug C is an antagonist to warfarin
B) Drug B inhibits metabolism of warfarin. Drug C enhances the activity of drug B
C) Drug B stimulates metabolism of warfarin. Drug C displaces warfarin from plasma binding proteins (Drug C enhances warfarin)
D) Drug B increases renal clearance of warfarin. Drug C inhibits metabolism of Drug B

Answer 4

C - A drug that stimulates metabolism of warfarin will DIMINISH the effect of warfarin. A drug that displaces warfarin from plasma binding proteins will ENHANCE the effect of warfarin

Question 5

Today’s patient is a 69 year old woman presenting with pain in her left thigh muscle. Duplex US indicates the presence of deep vein thrombosis in the affected muscle.

You decide to initiate treatment with enoxaparin. Compared to unfractionated heparin, enoxaparin:

A) Can be used without monitoring the aPTT
B) Has a shorter duration of action
C) Is less likely to have a teratogenic effect
D) Is more likely to be administered IV
E) Is more likely to cause thrombocytopenia

Answer 5

A - enoxaparin is a LMWH. LMWHs have a LONGER half life than plain or unfractionated heparin (UFH) and have a more consistent relationship between dose and effect. Enoxaparin is most often given SQ rather than IV, and is LESS LIKELY to cause TCP. UFH and LMWH do not cross the placenta and are not considered teratogens. UFH is usually used in patients who require monitoring of the aPTT, or prior to surgery or prior to delivery to take advantage of a shorter duration of action.

Question 6

Your patient today is a 57 year old woman with chronic HTN, and T2D recently discharged from the hospital for new onset atrial fibrillation and CHF. You have her hospital record, her echo and ECG. Her ECG is consistent with a fib. According to her risk score, she requires anticoagulation rather than antiplatelet therapy. You would like t ouse a direct thrombin inhibitor. Which of the following is a DTI?

A) Abciximab
B) Dabigatran
C) Rivaroxaban
D) Warfarin

Answer 6

B - abciximab is an antiplatelet agent that binds GPIIb/IIIa. Rivaroxaban is an oral factor Xa inhibitor.

Question 7

Is there a blood test we could order to use to monitor factor X?

A) Order the aPTT
B) Order an anti factor Xa test
C) INR
D) PT

Answer 7

B