Anticoagulants and Antiplatelets

Question 1

Know the factors common to both the intrinsic and extrinsic pathways of coagulation.

Answer 1

X, V, II (prothrombin: activated to IIa: thrombin), I (fibrinogen; activated to Ia: fibrin)

Four dependent on Vit K: II, VII, IX, X

Question 2

Heparin effects what part of the clotting cascade?

Answer 2

Main therapeutic affect on factors Xa and IIa

Question 3

How is heparin monitored?

Answer 3

Monitor anticoagulant effects via aPTT, anti-factor Xa assay, or heparin levels

Question 4

What are the Indications for Heparin?

Answer 4

PE and DVT treatment and prophylaxis

ACS – use depends on NSTEMI vs. STEMI and management strategy (PCI vs. medical); dosing protocols

Question 5

Side effects of Heparin:

Answer 5

Heparin induced thrombocytopenia can occur (HIT)

Long-term use may increase risk for osteoporosis

Question 6

Heparin is completely reversed by _________.

Answer 6

protamine sulfate

Question 7

T/F: Heparin does not require continual monitoring.

Answer 7

False, Inconsistent effects require monitoring

Question 8

_________ is the Anticoagulant of choice in severe renal dysfunction.

Answer 8

Heparin

Question 9

How is Heparin eliminated?

Answer 9

Eliminated via Reticuloendothelial system, not by kidneys

Question 10

How do we monitor Warfarin and what is the goal?

Answer 10

Monitor with INR; Normal: 0.9 – 1.1, goal: 2-3 (mitral valve replacement, 2.5-3.5)

Question 11

What are the indications for warfarin?

Answer 11

DVT, PE, antiphospholipid syndrome, atrial fibrillation, protein C/S deficiency, mechanical valve replacement, etc.

Question 12

Pearls of Warfarin:

Answer 12

Holding a dose often reduces INR by 0.5 – 1 point

Efficacious, cheap, old and known, no renal adjustments

Question 13

How long does it take for the therapeutic effects of warfarin? What is the adjustment based on?

Answer 13

Therapeutic effects take 2-3 days to start, 5-7 days for full effects. Loading only minimally effective. Adjust based on total weekly dose (TWD) by 10-20%. Monitor INR weekly until stable and then increase interval.

Question 14

What is the antidote of warfarin?

Answer 14

“Antidote” is vitamin K. PCC, FFP, platelets also given in cases of bleeding.

Question 15

Warfarin has ___________ benefits.

Answer 15

Cardioprotective benefits

Question 16

What is Dabigatran (Pradaxa)

Answer 16

Direct thrombin (IIa) inhibitor (ANTI-PLATELET).

Question 17

How does dabigatran work?

Answer 17

Orally active; inhibits free and clot-bound thrombin

Question 18

What is the half life of dabigatran adn where is it eliminated?

Answer 18

• T ½ 12-14 hours

* 80% renal elimination

Question 19

What are the indications for dabigatron?

Answer 19

Stroke and systemic embolism in AF

DVT/PE treatment and prophylaxis

Question 20

How is dabigatran dosed?

Answer 20

Warfaring -> Dabigatran: start dabigatran when INR < 2

Question 21

What are the pearls of dabigatran?

Answer 21

More effective for AF vs. warfarin; as effective in DVT/PE

Limited drug and no food interactions

No antidote or reliable way to stop/reverse bleeding

No way to monitor degree of anticoagulation

Question 22

Dabigatran is toxic to ________.

Answer 22

the heart

Question 23

Monitoring is required for which anticoag?

Answer 23

heparin

Question 24

What is an example of a LMWH?

Answer 24

Lovenox

Question 25

Is monitoring required for LMWH?

Answer 25

no

Question 26

What determines dosing for LMWH?

Answer 26

weight based dosing

Question 27

What are the indications for LMWH?

Answer 27

PE and DVT treatment and prophylaxis ACS – use depends on NSTEMI vs. STEMI and management strategy (PCI vs. medical); dosing protocols

Question 28

What drug can be used for patients with HIT?

Answer 28

arixtra

Question 29

What part of the clotting cascade do direct thrombin inhibitors function at?

Answer 29

factor IIa (thrombin), IV only

Question 30

Why dont we use more direct thrombin inhibitors?

Answer 30

they are expensive

Question 31

What does warfarin interact with?

Answer 31

Diet – vitamin K containing foods. Ok to consume, just have to maintain consistent intake Medications: o CYP: 2C9 >> 3A4 inhibitors and inducers– Amiodarone o Antibiotics: Septra, metronidazole

Question 32

What does CHADS2 score stand for?

Answer 32

CHF, HTN, Age (>75), DM, Stroke (2 points)

Question 33

What determines the treatment for a fib?

Answer 33

chads2 score

Question 34

what is the treatment for chads 1 score?

Answer 34

anticoag or ASA + plavix

Question 35

what is the treatment for chads 2 score?

Answer 35

anticoag or ASA + plavix

Question 36

What is the mechanism of action for asprin?

Answer 36

COX-1 inhibitor to prevent formation of TXA 2. Vasoconstriction, platelet aggrigation.

Question 37

T/F: low doses of ASA are as efficacious as higher doses

Answer 37

true

Question 38

What is the mechanism of action of clopidogrel?

Answer 38

irreversible inhibition of P@Y12 receptor, reduces platelet aggrigation.

Question 39

What is an indication for clopidogrel?

Answer 39

ACS

Question 40

What antiplatelets are used in orthopedic surgeries?

Answer 40

rivaroxaban (xarelto) and apixaban

Question 41

How is xarelto taken?

Answer 41

once daily dose, must take with meals

Question 42

When is prasugrel used?

Answer 42

in ACS patients with DM