Anticoagulants

Question 1

What test is used to monitor heparin therapy?

Answer 1

aPTT

Question 2

What test is used to monitor warfarin therapy?

Answer 2

PT-INR

Question 3

MOA of heparin

Answer 3

Binds to antithrombin III, enhancing its inhibition of factors IIa (thrombin), Xa, and IXa.

Question 4

Method of heparin administration

Answer 4

Intravenously or subcutaneously (not absorbed orally).

Question 5

Primary adverse effect of heparin therapy

Answer 5

Bleeding, followed by heparin-induced thrombocytopenia (HIT)

Question 6

What is used to Tx heparin overdose?

Answer 6

Protamine sulfate

Question 7

How does low-molecular weight heparin differ from UFH?

Answer 7

LMWHs are more selective for factor Xa and have more predicatable pharmocokinetics

LMWHs - i.e. Enoxaparin and dalteparin

Question 8

When is routine monitoring required in LMWH therapy?

Answer 8

Renal impairment

Pregnancy

Obesity

Question 9

What is fondaparinux and how does it work?

Answer 9

Synthetic heparin derivative that selectively inhibits factor Xa

There is no antidote for bleeding cuased by fondaparinux

Question 10

Two main types of direct oral anticoagulants

Answer 10

Factor Xa inhibitors and direct thrombin (factor IIa) inhibitors

Question 11

Name three examples of direct oral anticoagulants that inhibit Xa

Answer 11

1. Rivaroxaban
2. Apixaban
3. Edoxaban

Question 12

What is an example of a direct thrombin inhibitor

Answer 12

Dabigatran

Question 13

What should be monitored during direct oral anticoagulant therapy?

Answer 13

Kidney function

Question 14

What is the antidote for dabigatran

Answer 14

Idarucizumab

Dabigatran = direct thrombin inhibitor

Question 15

What is the antidote for rivaroxaban and apixaban?

Answer 15

Andexanet alfa

Question 16

What DOAC has the lowest risk of GI bleeding?

Answer 16

Apixaban

Question 17

Contraindications for DOAC therapy

Answer 17

Severe renal impairment and CYP450 inhibitors

Question 18

MOA of warfarin

Answer 18

Inhibits vitamin K epoxide reductase, preventing the synthesis of factors II, VII, IX, and X

Question 19

Why is warfarin’s onset of action delayed?

Answer 19

It only affects the synthesis of new clotting factors - takes 4-5 days

Question 20

Rare but serious side-effects of warfarin

Answer 20

Skin necrosis and purple-toe syndrome

Question 21

Why is warfarin contraindicated in pregnancy?

Answer 21

It is teratogenic and increases the risk of fetal bleeding

Question 22

What food/supplements increase bleeding risk w/ warfarin

Answer 22

1. Garlic
2. Ginger
3. Ginkgo biloba
4. Ginseng

Question 23

INR target for most warfarin Pt’s

Answer 23

2-3

Question 24

INR target for Pt’s w/ mechanical heart valves

Answer 24

2.5-3.5

Question 25

Antidote for warfarin overdose

Answer 25

Vitamin K In ermergent situations - fresh-frozen plasma or PCC

Question 26

Most common side-effect of long-term heparin use?

Answer 26

Osteoporosis

Question 27

Preferred anticoagulant used during pregnancy

Answer 27

LMWHs (i.e. enoxaparin)

Question 28

Preferred anticoagulant for Pt's with mechanical heart valves

Answer 28

Warfarin

Question 29

What anticoagulant is used to Tx heparin-induced thrombocytopenia?

Answer 29

Direct thrombin inhibitors like **argatroban**

Question 30

How are DOACs superior to warfarin in atrial fibrillation?

Answer 30

The require no routine monitoring and have fewer drug/food interactions

Question 31

What is the target range for PTT when using heparin?

Answer 31

1.5-2.5 times the Pt's baseline PTT

Question 32

Why is anti-factor Xa activity monitored in some LMWH Pt's?

Answer 32

To ensure efficacy in special populations (i.e. pregnancy/obesity)

Question 33

What test is used to monitor dabigatran effects?

Answer 33

Thrombin time or ecarin clotting time (ECT)

Question 34

Method of excretion of DOACs

Answer 34

Renal - why kidney Fx is monitored

Question 35

What reversal agent is used for excessive bleeding w/ rivaroxaban

Answer 35

Andexanet alfa

Question 36

Risk of using idarucizumab to reverse dabigatran

Answer 36

HA Hypokalemia Allergic rx'ns

Question 37

Why does efficacy of warfarin therapy vary between Pt's?

Answer 37

Genetic differences in CYP2C0 and vitamin K epoxide reductase

Question 38

Heparin indications

Answer 38

DVT PE MI

Question 39

Dilitazem (used for AF) interacts with what DOACs?

Answer 39

Rivaroxaban and apixaban

Question 40

Edoxaban and kidney function

Answer 40

Avoid edoxaban if kidney function is too good (i.e. CrCl > 95 mL/min)

Question 41

What type of bleeding risks is diminished in DOAC therapy compared to other anticoagulation?

Answer 41

Intracranial bleeding

Question 42

Indications for DOAC therapy

Answer 42

DVT/PE and prevent clots in A-fib

Question 43

Parenteral direct thrombin inhibitors

Answer 43

Lepirudin Bivalirudin Argatroban ## Footnote Commonly used in Pt's w/ prior Hx of heparin-induced thrombocytopenia (**HIT**) or during **angioplasty**

Question 44

Dabigatran

Answer 44

PO direct thrombin inhibitor

Question 45

Indications for warfarin therapy

Answer 45

DVT/PE A-fib and rheumatic heart disease to reduce stroke risk Mechanical heart valves or moderate-to-severe stenosis (warfarin should be selected insteads of DOACs in these Pts) Blocked coronary arteries (as an adjunctive therapy)

Question 46

To Tx major bleeding associated w/ warfarin use

Answer 46

Administer vitamin K (aka **phytonadione**) - slow reversal Fresh-frozen plasma or prothrombin complex concentrate (PCC)

Question 47

Hemostatic agents

Answer 47

Tranexamic acid Aminocarpoic acid **Displace plasminogen from fibrin**

Question 48

How to differentiate between warfarin therapy and DIC?

Answer 48

Only **DIC diminishes fibrinogen** serum concentration Warfarin inhibits Vit K epoxide reductase, and consequently diminished production of factors II, VII, IX, and X ## Footnote Low fibrinogen is one of the hallmarks of DIC - indicates widespread clotting and consumption of clotting factors

Question 49

How are unfractionated heparin's actions terminated?

Answer 49

Locally in endothelial cells and liver heparinases

Question 50

Which of the following is the most likely reason why lepirudin would be selected over heparin?

Answer 50

D) Previous episode of heparin-induced thrombocytopenia

Question 51

Which of the following inhibits thrombin exclusively?

Answer 51

C. Dabigatran

Question 52

Why is concurrent Tx w/ clarithromycin and apixiban contraindicated?

Answer 52

Clarithromycin inhibits cyp3A4 and P-glycoprotein which may increase risk of bleeding