CV Meds - antiplatelet drugs ADP-receptor antagonists and aspirin

Question 1

name 3 ADP-receptor antagonists

Answer 1

1. clopidogrel
2. ticagrelor
3. prasugrel

Question 2

give 3 indications for ADP-receptor antagonists

Answer 2

1. treatment of ACS - usually in combination with aspirin (where rapid inhibition of platelet aggregation can prevent or limit arterial thrombosis and reduce subsequent mortality
2. to prevent coronary artery stnet occlusion usually in combination with aspirin
3. seconday prevention of major CV event usually in combination with aspirin

Question 3

what does ADP stand for?

Answer 3

adenosine diphosphatase

Question 4

how do ADP receptor antagonists prevent aterial occlusion?

Answer 4

by binding (usually irreversibly) to ADP receptors on the surface of platelets to prevent platelet aggregation and therefore clots forming

Question 5

how are ADP receptor antagonists synergistic with aspirin?

Answer 5

because the ADP mechansim is independent of the COX pathway

Question 6

what 2 ADP receptor antagonists bind irreversibly and what one binds irreversibly?
whats the significance of this when it comes to surgery for instance?

Answer 6

irreversible = clopidogrel + prasugrel
reversible = ticagrelor
irreversible means their effects last for the lifespan of platelets (7-10 days) for should be stopped 7 days before surgery
reversible = antiplatelet effects wear off quicker so can be stopped 5 days before surgery

Question 7

give 3 important adverse effects of ADP receptor antagonists

Answer 7

1. bleeding - especially if GI or intracrainal
2. GI upset - dyspepsia, abdominal pain, diarrohea
3. thrombocytopenia - deficiency of platelets which can cause bleeding

Question 8

why happens to clopidogrels efficacy with CYP 450 inhibitors and why?

Answer 8

efficacy reduced becuase clopidgorel is a pro-drug activated by CYP450 enzymes therefore CYP450 inhibitors reduce its activation ./

Question 9

what PPI is preferred alongside clopidogrel?

Answer 9

lansoprazole or pantoprazole as less likely to inhibit clopidogrel activation than omeprazole