module 9 antiplatelet meds

Question 1

antiplatelet agents/classes

Answer 1

COX inhibitors
phosphodiesterase inhibitors
ADP receptor pathway inhibitors
GPIIb/IIIa antagonists

Question 2

platelet adhesion

Answer 2

fibrinogen

• connects platelets together for aggregation
• site of Rx

Question 3

Activation sites of Rx

Answer 3

ADP

Thromboxane A2

Question 4

Normal pathway of prostaglandin and platelet aggregation synthesis

Answer 4

• arachidonic acid is converted to prostaglandins by cycloxygenase (COX) : site of action
• prostaglandins converted to prostacylin by PGI2, and thromboxane A2 by TxA2 synthase.

Question 5

prostacylin

Answer 5

vasodilator

inhibits platelet aggregation by increases cAMP

Question 6

COX inhibitors

Answer 6

aspirin: irreversible
NSAID: reversible

Question 7

thomboxane a2

Answer 7

produced by activated platelets
prothrombotic properties
- stimulates activation of new platelets and increases aggregation

Question 8

COX inhibitors MOA

Answer 8

prevent the production of prostaglandins and in turn thromboxane A2 -> dec. platelet activation and aggregation

Question 9

aspirin

Answer 9

irreversible binding

-> continued inhibition for 7-10 even after stopping the med d/t life of platelet.

Question 10

ADP receptor inhibitors

Answer 10

ticlopidine
clopidogrel
prasugrel
ticagrelor
- call all be used in combo with ASA

Question 11

ADP receptor inhibitor MOA

Answer 11

irreversibly inactivate or antagonize the platelet P2Y(ADP) receptors -> inhibition of aggregation

Question 12

ADP receptors

Answer 12

activation causes platelets to undergo a shape change and aggregate to other platelets.

Question 13

ticlopidine

Answer 13

ADP receptor inhibitor
prodrug
binds irreversibly
maximal platelet inhibition within 8-11 days, 4-7 w/ ASA
- loading dose

Question 14

ticlopidine AE

Answer 14

neutropenia
thrombocytopenia
TTP
-> monitor CBC freq.

Question 15

clopidogrel

Answer 15

prodrug
binds irreversibly 
metabolized to active form by CYP2C19
- drugs that inhibit 2C19: omeprazole, esomeprazole 
loading dose 
lack of significant hematologic effects

Question 16

clopidogrel AE

Answer 16

GI adverse effects

Question 17

prasugrel

Answer 17

prodrug
more complete inhibition of P2Y(ADP) receptor 
binds irreversibly 
- more efficiently metabolized
- inc. concentration of active drug 
- inc. risk of bleeding

Question 18

ticagrelor

Answer 18

not a prodrug, drug is active form, also has active metabolites
reversible and non-competitive inhibition of P2Y(ADP)
Metabolized by CYP3A4

Question 19

GPIIb/IIIa antagonist

Answer 19

eptifibatide
abciximab
tirofiban
- administered IV

Question 20

GPIIb/IIIa

Answer 20

part of final common pathway of platelet aggregation

Question 21

abciximab AE

Answer 21

irreversible
- will need FFP infusion to stop bleeding
thrombocytopenia

Question 22

eprifibatide, tirofiban AE

Answer 22

reversible, but drug greatly out numbers receptors
- have to await drug clearance. New platelets will bind to free drug
thrombocytopenia

Question 23

dipyridamole

Answer 23

very weak platelet inhibitor