Anticoagulants, Antithrombotic and thrombolytics Flashcards
What are anticoagulants?
inhibits the blood coagulation cascade
What are antithrombotics?
inhibits the activation of blood platelets
What are thrombolytics?
Thrombolytics = fibrinolytics
dissolve blood clots
What are the types of anticoagulants?
In vitro (outside of living organism)- Heparin and EDTA In vivo (inside of living organism)- Low molecular weight heparin, oral anticoagulants (Warfarin)
Describe the mechanism, administration, uses and side-effects of Heparin (anticoagulant drug)
Mechanism:
- enhances action of antithrombin III
- heparin and antithrombin III inhibits the action of clotting factors
- low MW heparin only inhibits clotting factor Xa
Administration:
- given intravenous or subcutaneously
Uses:
- deep venous thrombosis
- pre-eclampsia of pregnancy
Side-effects:
- allergic reactions
- haemorrhage
- Heparin- induced Thrombocytopaenia
Describe the mechanism, administration, uses and side-effects of oral coagulant- Warfarin (anti-coagulant drug)
Mechanism:
- blocks Vitamin K reductase enzyme
- without sufficient Vitamin K
- clotting factors have decreases clotting ability
Administration:
- orally active
- in vivo
Uses:
- venous thrombosis
- prevents pulmonary embolism
Side-effects:
- haemorrhage
- crosses placenta and blood brain barrier so cannot be used in pregnancy
List the anti-thrombotic agents that may be used to treat arterial thrombosis.
- Low dose Aspirin
- Epoprostenol
- Clopidogrel
- Abciximab
- Dipyridamole
LECAD
Briefly describe the mechanism of anti-thrombotic agents
Low dose aspirin:
- inhibits COX enzyme
- prevents platelet aggregation
Epoprostenol
- stabilised prostacyclin
- > inhibits platelet activation
Clopidogrel
- blocks platelet ADP receptors- preventing GPIIb/IIIa receptor exposure
- prevents platelet aggregation
Abciximab
- blocks GPIIb/IIIa receptors
- can be used for coronary artery thrombosis
Dipyridamole
- inhibits enzyme that breaks down cAMP and cGMP
- increased levels of cAMP and cGMP
- prevents platelet aggregation
What anti-thrombotic agents prevent re-infarction risk?
and by what percentage?
- low dose aspirin
- Clopidogrel
prevent re-infarction risk by 20%
List thrombolytic (fibrinolytic) agents.
- Tissue Plasminogen Factor (t-PA)
- Streptokinase
Describe the mechanism of Tissue Plasminogen Factor.
Mechanism:
- enzyme produced by vascular endothelium
- activates plasminogen bound to fibrin into plasmin which converts fibrin polymer into soluble degradation products
Describe the mechanism of Streptokinase
Mechanism:
activates plasmniogen systemically
What are the uses and side effects of fibrinolytics/ Thrombolytics
- deep venous thrombosis
- MI
- Thrombotic stroke
- NOT used in haemorrhagic stroke
Side-effects:
- allergy (streptokinase- bacterium)
- haemorrhage (can be treated with tranexamic acid)
How would you reverse heparin induced side-effects?
heparin antagonist: protamine (binds to and inactivates heparin)
How would you reverse Warfarin induced side-effects?
oral vitamin K
