Anti thrombotic, platelet and coagulants Flashcards
What are the 3 classes of anti clotting drugs?
- Antiplatelets
- Anticoagulants
- Thrombolytics
Name the classes of anti platelet drug and example of each
- NSAID: aspirin
- Platelet receptor blockers: abciximab
- ADP receptor blockers: clopidogrel
- Phosphodiesterase inhibitors: Dipyridamole
What is the MOA of aspirin?
Blood thinner
Inhibitor COX, hence stop production of thromboxane which promotes platelet aggregation.
What is the MOA of platelet receptor blockers?
Activation of this receptor complex is the final common pathway for platelet aggregation.
By inhibiting this, effectively inhibit platelet aggregation
What is the clinical use of platelet receptor blockers?
Prevent restenosis after coronary angioplasty and are used in ACS
Name an ADP receptor antagonist and its MOA
Clopidogrel.
By binding irreversibly to the ADP receptor, clopidogrel inhibits the amplification of platelet activation signals, preventing the activation of the glycoprotein IIb/IIIa receptor on the platelet surface.
Reduced ability for platelets to aggregate - less chance of forming a clot
Name a phosphodiesterase inhibitor
Dipyridamole
Name 3 anticoagulants
- Warfarin
- Heparin
- Rivaroxaban
- Dabigatran
What is the MOA of warfarin?
Vitamin K antagonist. Since it is a critical component of synthesis of prothrombin, factor 7,9,10, it inhibits production of those factors and hence stop coagulation
What is the MOA of heparin?
Inhibits thrombin.
Heparin binds to anti thrombin 3, causing a conformational change to its active site
- this allows it to bind to thrombin (forming a 3 molecule complex) to inactivate thrombin
What is the action of thrombin?
- Cleaves fibrinogen to fibrin
- Activates factor 13
- Cause platelet aggregation and stimulate cell proliferation
** Compare low molecular weight heparins to regular unfractionated heparins.
Pro: LMWH have better bioavailability and longer half life.
Con: Increase the action of antithrombin 3 on factor 10a but NOT ON THROMBIN.
Which coagulation factor does LMWH act on?
Factor 10a
Can LMWH increase action of anti thrombin 3 on THROMBIN?
NO
What is the clinical use of heparin?
- Treatment of deep vein thrombosis, pulmonary embolism and acute MI
- Can be used when an anticoagulant is need in pregnancy
What is the adverse effect of giving IM heparin?
Hematomas!!!
What are the adverse effects of heparin?
Haemorrhage
Thrombocytopenia
Can warfarin be given to pregnant women?
NO
How is warfarin metabolised?
In the liver by CYPO450 enzymes
What are the adverse effects of warfarin?
Bleeding/haemorrhage
Cannot give during pregnancy (warfarin can cross placenta and cause haemorrhagic disorder)
Name 3 thrombolytic agents
- Alteplase
- Urokinase
- Streptokinase
- Anistreplase
What is the MOA of thrombolytic agents?
Dissolve an existing blood clot
Actively converts plasminogen to plasmin, the enzyme that catalyses the breakdown of fibrin to fibrin degradation products.
What are the ROAs of heparin?
IM or IV
What are the ROAs of thrombolytic agents?
IV or intracoronary
