Antiplatelets & Antithrombotics

Question 1

What causes atherosclerotic plaque?

Answer 1

an excess of cholesterol

Question 2

What happens if a thrombus ruptures and breaks off?

Answer 2

The embolus could get lodged in the capillaries and block the blood flow.
Could cause damage to organs downstream

Question 3

Damaged endothelial layers stimulate thrombus formation. What can cause this damage?

Answer 3

• atherosclerosis of arteries

- physical damage caused by balloon angioplasty and stenting

Question 4

What happens if a thrombus ruptures in an artery that peruses the brain?

Answer 4

• embolus gets stuck in cerebral capillary

- acute ischemic stroke

Question 5

What happens if a thrombus ruptures in an artery that perfuses the heart?

Answer 5

• embolus gets stuck in the coronary artery

- acute MI

Question 6

What happens if a venous thrombosis ruptures?

Answer 6

• embolus gets stuck in the lung capillaries

- pulmonary embolism

Question 7

Where are the 2 main sites that venous clots form?

Answer 7

• lower leg veins

- right atria

Question 8

Why don’t anti-platelet drugs work in the veins?

Answer 8

because clots in the veins involve RBCs, not platelets

Question 9

What are the 3 parts of formation of a platelet plug?

Answer 9

• platelet aggregation
• platelet activation
• platelet adhesion

Question 10

What is the purpose of coagulation?

Answer 10

• stabilize the platelet plug (clot)

- thrombin increases fibrin formation (reinforces plug)

Question 11

What is fibrinolysis?

Answer 11

• when the clot dissolves

- as the wound heals, it will destroy the clot

Question 12

Name 3 platelet inhibitors and the mechanism.

Answer 12

Aspirin - COX inhibitor
Clopidogrel - ADP receptor blocker
Abciximab - GP IIb/IIIa blocker

Question 13

Name 4 anticoagulants and their mechanism

Answer 13

Heparin - thrombin inhibitor
Warfarin - vitamin K antagonist
Dabigatran - thrombin antagonist
Rivaroxaban - factor Xa inhibitor

Question 14

Name a thrombolytic agent.

Answer 14

tPA –> tissue plasminogen activator

Question 15

What helps turn fibrinogen into fibrin?

Answer 15

thrombin

Question 16

What helps fibrin break down?

Answer 16

plasmin

Question 17

How can you prevent the formation of a platelet plug?

Answer 17

1. selective change in PG levels
   - increase/maintain endothelial prostacyclin
   - decrease TXa2 levels in platelets
2. block effects of released mediators
   - block ADP receptors–> blocks GPIIb/IIIa
3. prevent GPIIb/IIIa receptor coupling
   - block receptor

Question 18

Aspirin blocks COX, how does this work to be a platelet inhibitor?

Answer 18

• COX block PGI2 and TXa2
• PGI2 inhibition –> platelets more stable, less aggregation
• TXa2 inhibition –> platelets less sticky

Question 19

How do clots in the veins and arteries differ?

Answer 19

Arteries –> platelet-rich

Veins –> RBC-rich