2.9 Antiplatelet drugs

Secondary Prevention After Myocardial Infarction

Choice

Drug

Dosage

1st choiceAspirin dispersible tablets 75mg, 300mgDose:
Prophylaxis of cerebrovascular disease or myocardial infarction, initial loading dose of 300mg as a single dose, then 75mg daily

Management of Myocardial Infarction (STEMI or NSTEMI)

ChoiceDrugDosage
1st choicesAspirin indefinitely + P2Y12 inhibitor for up to 12 months then stopped.

The P2Y12 inhibitors are listed below and should be prescribed according to local trust protocol:

Dose:
Aspirin 75mg daily plus either:
· Clopidogrel
· Prasugrel (for patients undergoing PCI only)
· Ticagrelor

Clopdiogrel – Dose:
Initially 300-600mg as a single dose, then 75mg daily for up to 12 months

Or
Prasugrel – Dose:
Initally 60mg as a single dose then body-weight over 60Kg, 10mg once daily or body-weight under 60Kg or ELDERLY over 75 years, 5mg once daily for up to 12 months

Or
Ticagrelor – Dose:
Initally 180mg as a single dose, then 90mg twice daily for up to 12 months

Secondary Prevention in Cerebrovascular Disease, Peripheral Arterial Disease or Multivascular Disease

ChoiceDrugDosage
1st choiceClopidogrel 75mg tabletsDose:
Secondary prevention of ischaemic stroke and transient ischaemic attacks, 75mg daily

Prescribing Notes

  • The use of aspirin for primary prevention of cardiovascular events, in patients with or without diabetes, is of unproven benefit
  • Refer to NICE CG 172 MI – Secondary Prevention
  • There is no conclusive evidence that enteric-coated (e/c) preparations of aspirin are better tolerated, therefore the enteric coated formulation of aspirin is not recommended
  • In acute myocardial infarction, a loading dose of 300mg of dispersible or crushed (if enteric-coated) aspirin is given as early as possible after the onset of symptoms. Thereafter, a daily maintenance dose of 75mg aspirin is suggested
  • The combination of anticoagulant and antiplatelet therapy is sometimes used in selected patients. This should be prescribed under the care of a specialist. The combination significantly increases the bleeding risk so the duration of therapy should be clearly stated by secondary care. For further details refer to NICE CG 172 MI
  • Dual antiplatelet therapy with aspirin and clopidogrel is sometimes initiated by neurovascular specialists after a high risk TIA or a minor ischaemic stroke. Treatment is initiated within 24 hours of the onset of symptoms and continued for 10-21 days, at which point patients should continue with single antiplatelet therapy (usually clopidogrel). For further details see BMJ 2018;363:k5130
  • An interaction between PPIs and clopidogrel leading to reduction of antiplatelet effect has been reported, but the clinical significance is uncertain. If co-prescribing a PPI with clopidogrel is thought necessary, lansoprazole is currently preferred to omeprazole or esomeprazole. See Drug Safety Update –  Clopidogrel and proton pump inhibitors
  • Prasugrel 10 mg in combination with aspirin is recommended by NICE TA 317 as an option for preventing atherothrombotic events in adults with acute coronary syndrome having primary or delayed percutaneous coronary intervention
  • The NICE TA236-: Ticagrelor for the treatment of acute coronary syndromes  in October 2011 recommended ticagrelor as an option for up to 12 months in combination with low-dose aspirin in patients with STEMI being treated with primary PCI, NSTEMI, or unstable angina (plus ECG changes and specific high-risk clinical features)
  • Ticagrelor co-administered with aspirin is indicated for the prevention of atherothrombotic events in adult patients with acute coronary syndromes (ACS) or a history of myocardial infarction (MI) and a high risk of developing an atherothrombotic event.

For ACS:

    • Initiate treatment with a single 180mg loading dose (two tablets of 90mg) and then continued at a dose of 90mg twice daily.
    • Treatment with ticagrelor 90mg twice daily is recommended for 12 months unless earlier discontinuation is clinically indicated.
    • See extended treatment with ticagrelor for those at high risk of future atherothrombotic events below.
  • Extended treatment (following an initial 12 months course for ACS) in those deemed at high risk of a future atherothrombotic event:
      • A high risk of developing atherothrombotic events is defined as presence of at least one of the following five risk factors:
        • Age ≥65 years or
        • Diabetes mellitus requiring medication or
        • A second prior MI or
        • Evidence of multivessel coronary artery disease or
        • Chronic non-end stage renal dysfunction (creatinine clearance <60ml/min)
      • Ticagrelor may be extended at a LOWER dose of 60mg twice daily following an initial 12 month course of ticagrelor 90 mg twice daily. Extended treatment is most clinically effective if it commences immediately after the initial course rather than after a gap in treatment.
      • Extended treatment should be stopped after 3 years of 60mg twice daily, or earlier if clinically indicated e.g. if bleeding concern develops
      • See NICE TA420 for full details

Cautions

  • Aspirin and clopidogrel are contra-indicated in patients with active peptic ulceration and bleeding disorders.
  • Prasugrel is contraindicated in active bleeding, history of stroke or transient ischaemic attack.
  • Ticagrelor is contraindicated in active bleeding or history of intracranial haemorrhage.