Anti-platelet drugs Flashcards
1
Q
What happens in primary clotting?
A
- Platelet aggregation
- Thromboxane and ADP release by platelets
- Aggregation together and damaged part of endothelium
2
Q
What occurs in secondary clotting?
A
- Coagulation
- Thrombin stimulates platelet aggregation and forms fibrin polymer
- Fibrin mesh forms around clot
3
Q
What substances activate aggregation?
A
- Von-Willebrand factor and collagen (sub endothelial proteins)
- Thrombin
- ADP from activated platelet
- Thromboxane made by COX-1
4
Q
What substances aggregation inhibited by?
A
- Nitric oxide
- Prostacyclin
5
Q
What different anti-platelet drugs are there?
A
- Aspirin
- Clopidogrel
- Abeiximab
- Tirofiban
6
Q
What does aspirin do?
A
- Inhibits COX-1 so no thromboxane
7
Q
What does clopidogrel do?
A
- Blocks P2Y12 receptor also slows down chain reaction
8
Q
What do abeiximab and tirofiban do?
A
- Target glycoprotein gpIIb/ IIIa
9
Q
What does COX-1 do?
A
- Constitutive functions
- Inhibited- gastric bleeding
10
Q
What does COX-2 do?
A
- Inflammation and pain
- Inhibited- analgesia, anti-inflammatory effect
11
Q
How does aspirin work?
A
- High doses of aspirin and NSAIDs inhibit COX-1 and COX-2
- Therefore prostanoid synthesis
12
Q
Describe aspirin prescription in anti-platelet function
A
- Low dose
- Irreversibly acetylates COX-1 in platelets and endothelium
- Only endothelium can regenerate COX-1 enzyme due to nucleus to presence
13
Q
What are the clinical uses of low-dose aspirin?
A
- COX-1 inhibitor
- Low-dose front-line anti-platelet
- Prevention of MI
- Prophylaxis
- Thrombolysis after MI
14
Q
Describe the function of clopidogrel
A
- Pro-drug converted to active metabolite CP450 in liver
- Non-competitive, irreversible antagonist of platelet ADP receptors
- Reduces gpIIb/IIa reduceing aggregation
15
Q
What are the clinical uses of clopidogrel?
A
- Prevention of MI/ stroke
- Patients intolerant to low-dose aspirin
- After MI or intracoronary stent
