Anti-platelets + Anti-coagulants

Question 1

Which type of drug is used to treat arterial thrombosis?

Answer 1

Anti platelets e.g. aspirin

Question 2

Which type of drug is used to treat venous thrombosis?

Answer 2

Anti-coagulants e.g. warfarin, heparin, DOACs

Question 3

How does aspirin work?

Answer 3

Inhibits cyclo-oxygenase which is necessary to produce thromboxane A2 (a platelet agonist released from granules on activation)

Question 4

What are the side effects of aspirin?

Answer 4

1. bleeding
2. blocks production of prostaglandins:
   - GI ulceration
   - bronchospasm

Question 5

Name 4 other anti-platelet drugs other than aspirin?

Answer 5

Clopidogrel + prasugrel
Dipyridamole
Abciximab

Question 6

How do clopidogrel + prasugrel work?

Answer 6

ADP receptor antagonists

Question 7

How does dipyridamole work?

Answer 7

Phosphodiesterase inhibitor

- reduces production of cAMP which is a second messenger in platelet activation

Question 8

How does abciximab work?

Answer 8

GP IIb/IIIa inhibitor

–> inhibits aggregation of platelets

Question 9

How long do the effects of anti-platelets last after stopping taking them?

Answer 9

About 7-10 days (lifespan of platelets)

Question 10

What can do does to reverse anti-platelet function in severe bleeding?

Answer 10

Platelet transfusion

Question 11

What are the indications for anticoagulant drugs?

Answer 11

Venous thrombosis

Atrial fibrillation

Question 12

Which drugs are anticoagulants?

Answer 12

Heparin
Warfarin
Direct oral anticoagulants

Question 13

How does heparin work?

Answer 13

Potentiates antithrombin

Question 14

How is heparin given?

Answer 14

Parenteral –> SC or IV

Question 15

What are the type different types of heparin?

Answer 15

Unfractionated

LMWH

Question 16

Which monitoring is required for patients taking heparin?

Answer 16

Unfractionated –> APTT
LMWH –> can monitor anti-Xa assay but not usually required

FBC

Question 17

What are the complications of heparin?

Answer 17

Bleeding
Heparin induced thrombocytopenia (with thrombosis) - HITT
–> monitor FBC
Osteoporosis with long term use

Question 18

How is heparin reversed if necessary?

Answer 18

Stop the heparin (short half life)
If very severe bleeding:
–> protamine sulphate
- reverses antithrombin effect

Question 19

How does warfarin work?

Answer 19

Inhibits vitamin K

Question 20

Which factors are affected by inhibition of vitamin K?

Answer 20

2 (prothrombin), 7, 9, 10

Question 21

How is warfarin monitored?

Answer 21

INR - calculated from PT

Question 22

What are the options for management of bleeding in a patient on warfarin?

Answer 22

Oral vitamin K
Clotting factors (factor concentrates)

–> depends of severity of bleeding + INR

Question 23

How long does oral vitamin K take to work?

Answer 23

6 hours

Question 24

How long do clotting factors take to work?

Answer 24

Immediate

Question 25

Give some examples of the new oral anticoagulant drugs and how they work

Answer 25

Direct thrombin inhibitors –> dabigatran

Direct Xa inhibitors –> edoxaban, rivaroxaban, apixaban

Question 26

What are the advantages of DOACs?

Answer 26

Oral
No monitoring required
Less drug interactions
Recently developed specific antidotes