Adenosine diphosphate receptor inhibitors

Question 1

What is the mechanism of ADP receptor inhibitors?

Answer 1

• ADP: one of the main platelet activation factors
  
  • mediated by G-coupled receptors P2Y1 and P2Y12
• Main target of ADP receptor inhibition is the P2Y12 receptor
  
  • P2Y12 leads to sustained platelet aggregation and stabilisation of the platelet plaque

Question 2

What is the evidence for using ADP inhibitors and aspirin together?

Answer 2

• Multiple trials: a reduction in short- and long-term ischaemic events when using prasugrel and aspirin, compared to clopidogrel and aspirin in moderate to high-risk ACS patients.

Question 3

What are the long term treatment guidelines for ACS in terms of DAPT?

Answer 3

ACS

1. Aspirin (75mg daily)
2. Ticagrelor (90mg twice daily)

• for 12 months as secondary prevention strategy.

ACS with PCI

1. Aspirin (75-100mg daily)
2. Prasugrel (10mg daily)

or ticagrelor (90mg twice daily)

or clopidogrel (75mg daily - if above two unsuitable)

• for 12 months
  3. Aspirin alone thereafter

Question 4

What interactions do ADP inhibitors have?

Answer 4

• Interaction exists between clopidogrel and omeprazole and esomeprazole :. reducing antiplatelet effects

Question 5

What are the contraindications for ADP inhibitors?

Answer 5

1. Absolute contraindications to prasugrel use:

• ​​​​prior stroke or transient ischaemic attack
• high risk of bleeding
• prasugrel hypersensitivity

1. Ticagrelor is contraindicated:
   
   • high risk of bleeding
   • history of intracranial haemorrhage,
   • severe hepatic dysfunction
   • caution in those with acute asthma or COPD
     
     • ​ticagrelor-treated patients experience higher rates of dyspnoea