8.1 Antiplatelets and Anticoagulants Flashcards
What do you use with problems with the arteries?
Antiplatelets
What do you use with problems with the venous system?
Anticoagulants
What are some anticoagulants?
Warfarin
Heparin
Factor IIa and Xa inhibitors
What are some antiplatelets?
Aspirin
GpIIb/IIa inhibitors
Dypyramidole
Clopidogrel
What are some fibrinolytic agents aka clot busters?
Streptokinase
-plases
What factors does Warfarin act on?
Factor II, VII, IX, X
How does Warfarin work?
Inhibits vitamin K reductase
No reduced vit K available for synthesis of Prothrombin from Decarboxyprothrombin
Inhibits coagulation cascade
Both intrinsic and extrinsic pathways effected
Why do you have to be careful with warfarin?
Bleeding risk - IC Haemorrhage, GI bleeding
Monitor the INR carefully, titrate doses when perscribing
Tetaratogenic
When do you use Warfarin?
DVT PE (48hrs after) AF Prosthetic Valves Recurrent Thrombosis
DDIs with Warfarin?
P450 Inducers and Inhibitors Antibiotics (cephalosporins) that reduce gut flora Antiplatelets (potentiate) Albumin displacement by NSAIDs Liver Disease
Anti epileptics inhibit
How does heparin work?
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)
What are the types of heparin?
Bioavailability?
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
Why use heparin?
Peri-op
Immediate cover for DVT/PE/AF as warfarin takes ~3 days to work
What are some examples of Factor IIa inhibitors?
Xa?
IIa Argatroban
Xa fondaparinine, edoxaban
Why use IIa/Xa inhibitors?
Fewer side effects and interactions
Why not use IIa/Xa inhibitors?
Very expensive
What do you do in a heparin OD?
Stop Heparin
Use Protamine Sulphate - dissociates heparin from ATIII and binds irreversibly to heparin
Heparin ADRs?
Bleeding risk
Thrombocytopenia
Osteoporosis
How does Aspirin work as an antiplatelet?
It inhibits COX 1
This decreases the production of thromboxane from damaged vessels etc to prevent platelet aggregation
What are GpIIb/IIIa inhibitors?
They are antiplatelets
they prevent fibrin from making crosslinks with platelets, prevent aggregation of platelets
When would you use GpIIb/IIIa inhibitors?
post-PCI and in high risk acute coronary syndrome
What is dipyramidole?
Antiplatelet
Inhibits phosphodiesterase from breaking down cAMP to prevent aggregation
When do you use dipyramidole?
Post Strokes
What is Clopidogrel?
block P2Y12 Gi receptor which usually decreases cAMP
inhibits ADP dependent aggregation
