Antiplatelet and fibrinolytic drugs Flashcards
What are antiplatelet drugs primarily used for
Arterial thrombosis
- Acute myocardial infarction
- In patients with risk of myocardial infarction
- Following coronary bypass
- Unstable coronary syndromes
- Following coronary artery angioplasty
- Transient cerebral ischaemic attack or thrombotic stroke
Give an example of an COX inhibitor that is an antiplatelet
Asprin
what is the mechanism of action of asprin
- It irreversibly inactivates COX 1/ 2 (cyclooxygenase) resulting in decreased levels of TXA2 and consequentially inhibition of vasoconstriction and platelet aggregation
- Platelets then take 7-10 days to replace COX but endothelial cells can replace it immediately
Describe the different dosages of asprin and what they are used for
- Low dose (180mg/day) → effective in preventing a mini storke
- 335mg/day → reduce risk of heart attack
- > 1000mg/day → no effect die to great inhibiton of endothelial COX
What is the clinical use of asprin
•In acute myocardial infarction in combination with fibrinolytic drugs
Give examples of antiplatelet drugs that are ADP receptor antagonists
Ticlopidine
Clopidogrel
Prasugrel
Ticagrelor
What is the mechanism of action of Ticlopidine,
Clopidogrel and Prasugrel
- Irreversible antagonist at the ADP receptor thereby reducing the release of ADP
- This prevents the expressing of glycoprotein IIBb/IIIa receptors and consequentially reduces platelet aggregation
what is the mechanism of action of Ticagrelor
- Reversible antagonist at the ADP receptor thereby reducing the release of ADP
- This prevents the expressing of glycoprotein IIBb/IIIa receptors and consequentially reduces platelet aggregation
what is the onset of action of Ticlopidine
•Slow onset of 3-7 days
What is the clinical use of Ticlopidine
•Reducing the risk of stroke
What are the side effects of Ticlopidine (which consequentially limit the use of the drug)
- Rash
- Dirrhoea
- Neutropenia
How is Clopidogrel administrated
• Prodrug, oral administration
What is the clinical use of Clopidogrel
- In combination with asprin
* It reduces the risk of ischaemic stroke, myocardial infarction and vascular death
What are the side effects of Clopidogrel
•Less side effects than Ticlopidine especially neutropenia
What is the onset of Prasugrel
- Faster onset than clopidogrel
* Hours
What are the side effects of Prasugrel
•More efficacious than clopidogrel so greater chance of bleeding
what is the efficacy of Ticagrelor
•Similar efficacy to prasugrel and clopidogrel
what is the clinical use of Ticagrelor
•Its reversibility is an asset in certain clinical scenarios
give examples of antiplatelet drugs that are IIb/IIIa receptor antagonists
Abciximab/ Tirfiban
Tirofiban/ Eptifibatide
what is the mechanism of action of Abciximab and Tirfiban
•It is an antibody fragment directed at inhibiting the GP IIb/IIIa receptor and consequentially inhibiting platelet aggregation
What is the clinical use of Abciximab and Tirfiban
•Used by IV infusion in high risk coronary angioplasty patients with heparin and asparin
Why can Abciximab and Tirfiban only be administered once
•Its immunogenicity limits the use to a single administration
What is the platelet recovery time following Abciximab or Tirfiban use
•Platelet function is recovered in days
What is the mechanism of action of Tirofiban and Eptifibatide
•Cyclic peptides which lesemble IIb/IIIa ligands