Patient on anti-coagulant therapy

Question 1

What are anticoagulants?

Answer 1

Used for treating and preventing embolic events

Question 2

What are the most common oral anticoagulants?

Answer 2

• Vitamin K antagonists e.g. Warfarin
• DOACs e.g. Apixaban

Question 3

What is the most common parenteral anticoagulant?

Answer 3

Heparin

Question 4

What is vitamin K responsible for?

Answer 4

Production of factors 2, 7, 9, 10

Question 5

How does Vitamin K affected PT and APTT?

Answer 5

Prolonged PT as it has the biggest affect on factor 7

Normal APTT

Question 6

What is an advantage of warfarin?

Answer 6

Can be directly reversed by replacement of vitamin K

Question 7

What are disadvantages of warfarin?

Answer 7

• Long half-life (Warfarin’s long half-life means that it remains effective for several days after it is stopped- risk of thrombosis)
• Regular monitoring of PT and INR
• Lots of drug-drug interactions
• Not used in PE and DVT

Question 8

What is the target INRs of patients on warfarin and what is the exception?

Answer 8

2.5 except mitral valve replacement

Question 9

What is the INR target in metallic mitral valve replacement?

Answer 9

2.5-3.5

Question 10

What is the INR target following VTE, for AF and for metallic aortic valve replacement?

Answer 10

2.0-3.0

Question 11

What is the INR target for recurrent PEs?

Answer 11

3.5

Question 12

What do we do if INR is raised significantly?

Answer 12

Indicates high bleeding risk → warfarin reduced/withheld completely and vitamin K may be given and FFP

Question 13

What do we do 6-8 hours before emergency surgery (if it can wait) in terms of warfarin?

Answer 13

6-8 hrs before surgery: Give IV 5mg vitamin K

Question 14

What do we do before emergency surgery (if it can’t wait) in terms of warfarin?

Answer 14

Give 25-50 units/kg four-factor prothrombin complex

Question 15

List examples of DOACs

Answer 15

• Apixaban
• Rivaroxaban
• dabigatran

Question 16

How does apixaban/ rivaroxaban work?

Answer 16

Factor 10a inhibitors

Question 17

How does dabigatran work?

Answer 17

Direct thrombin inhibitor

Question 18

Why are DOAC’s preferred over warfarin?

Answer 18

Require less monitoring

Question 19

What is the short acting heparin called?

Answer 19

Unfractionated heparin (standard)

Question 20

How is short acting heparin administered?

Answer 20

IV (unfractionated heparin)

Question 21

How is hort acting heparin monitored?

Answer 21

APTT

Question 22

What is the long acting heparin called?

Answer 22

Low Molecular Weight Heparin

Question 23

Give an example of LMWH

Answer 23

Enoxaparin or dalteparin

Question 24

How is LMWH administered?

Answer 24

Subcutaneous

Question 25

How is LMWH monitored?

Answer 25

Via anti-factor 10a

Question 26

Which is usually preferable, b/t short and long acting heparin and why?

Answer 26

LMWH → Preferred as there is a lower risk of heparin-induced thrombocytopenia

Question 27

How does heparin-induced thrombocytopenia occur?

Answer 27

Heparin activates antithrombin III, which forms a complex that inhibits factor 10a

Question 28

What is the reversal agent for heparin?

Answer 28

Protamine sulfate

Question 29

How is bleeding risk calculated?

Answer 29

ORBIT score

Question 30

How long before planned surgery must warfarin be stopped?

Answer 30

5 days

Question 31

What is the target INR for surgery to go ahead?

Answer 31

When persons INR is <1.5

Question 32

What do you do if INR> 1.5 before surgery?

Answer 32

Give oral vitamin K a day before surgery

Question 33

When is warfarin contraindicated?

Answer 33

Avoid in pregnancy

Question 34

How long before planned surgery must heparin be stopped?

Answer 34

May be stopped on day of surgery, since heparin has a much shorter half-life than warfarin

Question 35

What things reduce warfarin activity?

Answer 35

P450 Inducers (Induce = reduce INR)

Question 36

What are some examples of P450 inducers?

Answer 36

**SCARS** - Smoking - Ciroc (alcohol) - Anti-epileptics e.g. Carbamazepine or Phenytoin - Rifampicin - St Johns wart

Question 37

What things increase warfarin activity?

Answer 37

P450 inhibitors increase warfarin activity (increase INR)

Question 38

What are some examples of P450 inhibitors?

Answer 38

**ASS ZOLES** - Antibiotics- such as? **(4)** - Ciprofloxacin - Isoniazid - Clarithromycin - Erythromycin - SSRIs e.g. fluoxetine, sertraline - Sodium valproate - -zoles → such as? **(3)** - Omeprazole - Ketoconazole - Fluconazole

Question 39

What do we give to reverse dabigatran?

Answer 39

Idarucizumab (humanised monoclonal antibody fragment that binds specifically to dabigatran and its metabolites, thereby reversing the anticoagulant effect.)

Question 40

How do you reverse DOAC?

Answer 40

Andexanet alfa (Andexanet alfa is a recombinant form of human factor Xa protein which binds specifically to apixaban or rivaroxaban, thereby reversing their anticoagulant effects.)

Question 41

How do you manage major bleeding and high INR?

Answer 41

- Stop warfarin - Oral/IV vitamin K - Prothrombin complex concentrate

Question 42

How do you manage minor bleeding and INR is >5 (or no bleeding but INR >8)? (3)

Answer 42

- Stop warfarin - Oral/IV vitamin K - Restart warfarin when INR is <5

Question 43

How do you manage no bleeding and INR is 5-8?

Answer 43

Withhold 1 or 2 doses of warfarin

Question 44

What do you do if INR <2?

Answer 44

Up warfarin dose and start LMWH