antiplatelets

Question 1

prostacyclin?

Answer 1

produced and released by endothelial cells – inhibits platelet aggregation
↑[cAMP] → ↓calcium - preventing platelet aggregation
↓in platelet aggregatory agents

Question 2

compare venous and arterial thrombosis

Answer 2

Venous: stasis of blood and or damage to the veins – less likely to see
endothelial damage
High red blood cell and fibrin content, low platelet content evenly distributed, parenteral anticoagulants
• Arterial: forms at site of atherosclerosis following plaque rupture
Lower fibrin content and much higher platelet content
antiplatelet and fibrinolytic drugs used

Question 3

platelet activation and aggravation

Answer 3

• Release of platelet granules
• activation and aggregation through GPIIb/IIIa receptors and fibrinogen
• ↑calcium and ↓cAMP in platelets
• Cascade and amplification from platelet to platelet

Question 4

Cyclo-oxygenase inhibitor example

Answer 4

aspirin

Question 5

Cyclo-oxygenase inhibitor mechanism

Answer 5

• Potent platelet aggregating agent thromboxane A2 (TXA2) formed from arachidonic acid by COX-1
• Aspirin - inhibits COX-1 mediated production of TXA2 and reduces platelet aggregation –irreversible
Higher doses inhibit endothelial prostacyclin (PGI2)
Absorbed by passive diffusion – hepatic hydrolysis to salicylic acid

Question 6

Cyclo-oxygenase inhibitor

Answer 6

Gastrointestinal irritation, GI bleeding (peptic ulcer), haemorrhage (stroke)
hypersensitivity

Question 7

X Cyclo-oxygenase inhibitor

Answer 7

Reye’s syndrome – avoid <16 years
Hypersensitivity
3rd trimester – premature closure of ductus arteriosus

Question 8

^Cyclo-oxygenase inhibitor

Answer 8

other antiplatelet and anticoagulants

Question 9

Cyclo-oxygenase inhibitor indication

Answer 9

Afib post stroke,
secondary prevention of stroke and TIA,
Post primary percutaneous coronary intervention (PCI)
NSTEMI/Stemi

Question 10

ADP receptor antagonists mechanism

Answer 10

Inhibit binding of ADP to P2Y12 receptor → inhibit activation of GPIIb/IIIa receptors
independent of COX pathway

Question 11

ADP receptor antagonists example

Answer 11

clopidoGREL-irreversible, prodrug, slow onset
prasuGREL- irreversible, prodrug, rapid onset
ticaGRELor- reversible

Question 12

ADP receptor antagonists

Answer 12

Bleeding!
GI upset – dyspepsia and diarrhoea
rarely - thrombocytopenia

Question 13

^ADP receptor antagonists

Answer 13

clopidogrel requires CYPs for activation
CYP inhibitors – omeprazole, ciprofloxacin, erythromycin, some SSRIs, PPIs
ticagrelor can interact with CYP inhibitors and inducers
other antiplatelet and anticoagulant agents or NSAIDs – increased bleeding risk

Question 14

X ADP receptor antagonists

Answer 14

caution in high bleed risk patients with renal and hepatic impairment

Question 15

ADP receptor antagonists indication

Answer 15

second agent in “dual antiplatelet therapy”
Ischaemic stroke
N/STEMI

Question 16

Phosphodiesterase inhibitors

example

Answer 16

dipyridamole

Question 17

Phosphodiesterase inhibitors mechanism

Answer 17

inhibits cellular reuptake of adenosine → increased [adenosine] → inhibits platelet aggregation via adenosine (A2) receptors
• prevents cAMP degradation → inhibit expression of GPIIb/IIIa

Question 18

Phosphodiesterase inhibitors

Answer 18

Vomiting and diarrhoea

dizziness

Question 19

^Phosphodiesterase inhibitors

Answer 19

antiplatelets and anticoagulants, adenosine

Question 20

Phosphodiesterase inhibitors indication

Answer 20

prevention of ischaemic stroke and TIAs

Question 21

Glycoprotein IIb/IIIa inhibitors example

Answer 21

abciximab Administered i .v.

Question 22

Glycoprotein IIb/IIIa inhibitors mechanism

Answer 22

Blocks binding of fibrinogen and von Willebrand factor (vWF)

Question 23

Glycoprotein IIb/IIIa inhibitors

Answer 23

Bleeding! dose adjustment for body weight

Question 24

^ Glycoprotein IIb/IIIa inhibitors

Answer 24

other antiplatelet and anticoagulant agents

Question 25

Glycoprotein IIb/IIIa inhibitors indication

Answer 25

Specialist use in high risk percutaneous transluminal coronary angioplasty
patients with other drugs

Question 26

Fibrinolytic agents (thrombolysis) “clot busters”
example

Answer 26

streptokinase (only administered once), alteplase: plasminogen turns into plasmin

Question 27

Fibrinolytic agents (thrombolysis) “clot busters” indication

Answer 27

Alteplase (t PA ) in acute ischaemic stroke <4.5 hours from symptoms
• Following STEMI diagnosis acutely vs. primary PCI

Question 28

Fibrinolytic agents (thrombolysis) “clot busters”

Answer 28

Bleeding

Question 29

^Fibrinolytic agents (thrombolysis) “clot busters”

Answer 29

antiplatelets and anticoagulants