8.1 Antiplatelets and Anticoagulants

Question 1

What do you use with problems with the arteries?

Answer 1

Antiplatelets

Question 2

What do you use with problems with the venous system?

Answer 2

Anticoagulants

Question 3

What are some anticoagulants?

Answer 3

Warfarin
Heparin
Factor IIa and Xa inhibitors

Question 4

What are some antiplatelets?

Answer 4

Aspirin
GpIIb/IIa inhibitors
Dypyramidole
Clopidogrel

Question 5

What are some fibrinolytic agents aka clot busters?

Answer 5

Streptokinase

-plases

Question 6

What factors does Warfarin act on?

Answer 6

Factor II, VII, IX, X

Question 7

How does Warfarin work?

Answer 7

Inhibits vitamin K reductase
No reduced vit K available for synthesis of Prothrombin from Decarboxyprothrombin
Inhibits coagulation cascade
Both intrinsic and extrinsic pathways effected

Question 8

Why do you have to be careful with warfarin?

Answer 8

Bleeding risk - IC Haemorrhage, GI bleeding
Monitor the INR carefully, titrate doses when perscribing

Tetaratogenic

Question 9

When do you use Warfarin?

Answer 9

DVT
PE (48hrs after)
AF
Prosthetic Valves
Recurrent Thrombosis

Question 10

DDIs with Warfarin?

Answer 10

P450 Inducers and Inhibitors
Antibiotics (cephalosporins) that reduce gut flora 
Antiplatelets (potentiate)
Albumin displacement by NSAIDs
Liver Disease

Anti epileptics inhibit

Question 11

How does heparin work?

Answer 11

It increases the production of the antithrombin thrombin complex
Inhibits factor X and IIa
Acts on the intrinsic pathway (no effect on PT time, by APTT time and INR increase)

Question 12

What are the types of heparin?

Bioavailability?

Answer 12

Unfractionated - affects factor XII, XI, IX and X and inhibits IIa

Low Molecular Weight - can only inhibit factor X
90% BioA and long half life
Has a more predictable dose response

Question 13

Why use heparin?

Answer 13

Peri-op

Immediate cover for DVT/PE/AF as warfarin takes ~3 days to work

Question 14

What are some examples of Factor IIa inhibitors?

Xa?

Answer 14

IIa Argatroban

Xa fondaparinine, edoxaban

Question 15

Why use IIa/Xa inhibitors?

Answer 15

Fewer side effects and interactions

Question 16

Why not use IIa/Xa inhibitors?

Answer 16

Very expensive

Question 17

What do you do in a heparin OD?

Answer 17

Stop Heparin

Use Protamine Sulphate - dissociates heparin from ATIII and binds irreversibly to heparin

Question 18

Heparin ADRs?

Answer 18

Bleeding risk
Thrombocytopenia
Osteoporosis

Question 19

How does Aspirin work as an antiplatelet?

Answer 19

It inhibits COX 1

This decreases the production of thromboxane from damaged vessels etc to prevent platelet aggregation

Question 20

What are GpIIb/IIIa inhibitors?

Answer 20

They are antiplatelets

they prevent fibrin from making crosslinks with platelets, prevent aggregation of platelets

Question 21

When would you use GpIIb/IIIa inhibitors?

Answer 21

post-PCI and in high risk acute coronary syndrome

Question 22

What is dipyramidole?

Answer 22

Antiplatelet

Inhibits phosphodiesterase from breaking down cAMP to prevent aggregation

Question 23

When do you use dipyramidole?

Answer 23

Post Strokes

Question 24

What is Clopidogrel?

Answer 24

block P2Y12 Gi receptor which usually decreases cAMP

inhibits ADP dependent aggregation

Question 25

When do you use Clopidogrel?

Answer 25

with Aspirin for more serious bleeds (not long term)

PCI and ACS (long term)