Anti-platelets

Question 1

How does aspirin work?

Answer 1

blocking the action of both cyclooxygenase-1 and 2. Cyclooxygenase is responsible for prostaglandin, prostacyclin and thromboxane synthesis. The blocking of thromboxane A2 formation in platelets reduces the ability of platelets to aggregate which has lead to the widespread use of low-dose aspirin in cardiovascular disease.

Question 2

What potentiates aspirin?

Answer 2

oral hypoglycaemics
warfarin
steroids

Question 3

what is aspirin used for?

Answer 3

first-line for patients with ischaemic heart disease

Question 4

When do you use clopidogrel?

Answer 4

clopidogrel is also now first-line in patients following an ischaemic stroke and in patients with peripheral arterial disease.

Question 5

Give some other examples of thienopyridines

Answer 5

prasugrel
ticagrelor
ticlopidine

Question 6

What is the MOA of thienopyridines

Answer 6

antagonist of the P2Y12 adenosine diphosphate (ADP) receptor, inhibiting the activation of platelets

Question 7

What are the interactions with thienopyridines

Answer 7

concurrent use of proton pump inhibitors (PPIs) may make clopidogrel less effective (MHRA July 2009)
this advice was updated by the MHRA in April 2010, evidence seems inconsistent but omeprazole and esomeprazole still cause for concern. Other PPIs such as lansoprazole should be OK - please see the link for more details

Question 8

Give some examples of Glycoprotein IIb/IIIa receptor antagonists

Answer 8

abciximab
eptifibatide
tirofiban

Question 9

What is the MOA of Glycoprotein IIb/IIIa inhibitors?

Answer 9

prevent platelet aggregation by blocking the binding of fibrinogen to receptors on platelets.