A - 16. Drugs used in coagulation disorders I: Antiplatelet agents

Question 1

Primary homeostasis steps

Answer 1

1. Endothelial injury
2. Exposure of collagen -> vWF binds
3. Adhesion - platelets binds via GP Ib
4. Activation - platelets change shape and release vWF + serotonin + ADP + TXA2
5. Aggregation - GP IIb/IIIa receptors causes fibrinogen binding

Question 2

Acetylsalicylic acid

Answer 2

Aspirin - NSAID
Blocks TXA2: acetylation of COX1 and COX2 -> inhibition of TXA2 production

Given for regular anti clot use, and acutely against strokes and MI’s. Low dose - prophylaxis

SE: gastric ulcers, allergic reactions

Question 3

ADP receptor inhibitor names

Answer 3

Clopidogrel
Prasugrel
Tiacagrelor

Question 4

ADP receptor inhibitor action

Answer 4

Binds to ADP receptor, which blocks ADP binding

Clopidogrel and prasugrel: irreversible binding by their metabolites after being metabolized by liver

Tiacagrelor: reversible, non comp. - decreases ADP receptors affinity

Question 5

ADP receptor inhibitor indications and toxicity

Answer 5

Used in combo with aspirin in ACS and a lot of other cardio shit

Can cause thrombotic thrombocytopenic purpura

Question 6

GP IIb/IIIa inhibitors

Answer 6

Abciximab

• monoclonal AB
• Binds directly to GP IIb/IIIa receptor -> inhibits fibrinogen binding
• used for unstable angina and other coronary procedures