Anti-coagulants

Question 1

What are indications for anti-coagulants?

Answer 1

Atrial fibrillation
VTE
MI
Stroke/TIA

Hypercoagulability disorders

Question 2

What are some inherited hypercoagubility disorders?

Answer 2

Factor V Leiden deficiency
- blood vessels cannot heal normally

Protein C deficiency
- protein C prevents blood clotting

Protein S deficiency
- protein S regulates blood clotting

Question 3

What are some examples of acquired hypercoagubility?

Answer 3

Cancer
Trauma
Immobility

Question 4

What are the oral anticoagulants?

Answer 4

Warfarin

DOACs

• apixaban
• rivaroxaban

Question 5

What are the parental anticoagulants?

Answer 5

Heparin

• UFH
• LMWH

Heparin alternatives

Question 6

What is INR?

Answer 6

International normalised ratio

INR = patient prothrombin time / control

Question 7

What is a normal INR?

Answer 7

1.1

Question 8

What INR is required for elective surgery?

Answer 8

<1.5

Question 9

What is the action of warfarin?

Answer 9

Vitamin K antagonist

• inhibits vitamin K epoxide reductase
• stops conversion of vitamin K to active form
• vitamin K required for synthesis of factors II, VII, IX, X

Question 10

What is the absorption of warfarin?

Answer 10

Oral bio-availability 79-100%

Question 11

What is the distribution of warfarin?

Answer 11

Protein binding 99%

Question 12

What organ metabolises warfarin?

Answer 12

Liver

Question 13

What organ excretes warfarin?

Answer 13

Kidney

Question 14

What is the reversal of warfarin?

Answer 14

Vitamin K

Question 15

How long before surgery do you need to stop warfarin?

Answer 15

5 days

Check INR

Question 16

What are the actions of DOACs?

Answer 16

Factor Xa inhibitor

Question 17

What is the absorption of DOACs?

Answer 17

Oral bio-availability 50-70%

Question 18

What is the distribution of DOACs?

Answer 18

Protein binding 87%

Question 19

What organ metabolises DOACs?

Answer 19

Liver

Question 20

What organ excretes DOACs?

Answer 20

Kidney

Some excreted by bile

Question 21

What is the reversal of DOACs?

Answer 21

Andexanet alfa

Question 22

How long before surgery do you need to stop DOACs?

Answer 22

24 hours

48 hours if poor renal function

Question 23

What is the action of unfractioned heparin?

Answer 23

Inhibits antithrombin III

- antithrombin III activates factors XIIa, XIa, IXa, Xa, IIa

Question 24

What are the low molecular weight heparins?

Answer 24

Dalteparin

Enoxaparin

Question 25

What is the action of LMWHs?

Answer 25

Inhibit factor Xa

Question 26

What is the absorption of heparin?

Answer 26

IV (UFH) | SC (LMWH)

Question 27

What is the distribution of heparin?

Answer 27

Plasma volume

Question 28

What organ metabolises heparin?

Answer 28

Liver

Question 29

How is heparin excreted?

Answer 29

Urine

Question 30

What is heparin reversal?

Answer 30

Protamine - forms an inactive ion pair with heparin - dissociates heparin from ATIII

Question 31

How long before surgery do you need to stop heparin?

Answer 31

Heparin stops working after 90 mins Monitor APTT

Question 32

What is APTT?

Answer 32

Activated partial thromboplastin time Measure of the functionality of the intrinsic and common pathways of the coagulation cascade

Question 33

How long before surgery do you need to stop LMWH?

Answer 33

Wait 12 hours - prophylactic dose Wait 24 hours - treatment dose

Question 34

What are the commonly used anti-platelet agents?

Answer 34

Aspirin | Clopidogrel

Question 35

What is the action of aspirin?

Answer 35

Reduction of TXA2 synthesis by COX-1 inhibition - inhibits platelet aggregation

Question 36

What is the action of clopidogrel?

Answer 36

ADP receptor antagonist | - inhibit activation of GPIIb/IIIa

Question 37

How long before surgery do you need to stop aspirin?

Answer 37

Can continue it

Question 38

How long before surgery do you need to stop clopidogrel?

Answer 38

Stop 7 days before