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Home Formulary 2.0 Cardiovascular System 2.9 Antiplatelet drugs

2.9 Antiplatelet drugs

(i) Management of Myocardial Infarction (STEMI or NSTEMI)

Refer to NICE NG185 and local trust protocol for early management / initial drug therapy.

Initial drug therapy and secondary prevention after myocardial infarction:  

Choice

Drug

Dose

1st choiceAspirin dispersible tablets 75mg, 300mgInitial loading dose of 300mg as a single dose, then 75mg daily

Dual antiplatelet therapy secondary prevention after myocardial infarction:

ChoiceDrugDosage
1st choice

Aspirin indefinitely plus:  

Aspirin 75mg daily plus:

P2Y12 inhibitor for up to 12 months then stopped.

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

  • Ticagrelor
  • Clopidogrel
  • Prasugrel (for patients undergoing PCI only)
TicagrelorTicagrelor:
Initially 180mg as a single dose, then 90mg twice daily for up to 12 months
or
ClopidogrelClopidogrel:
Initially 300 to 600mg as a single dose, then 75mg daily for up to 12 months
or
PrasugrelPrasugrel:
Adult 18–74 years (body-weight up to 60kg)
Initially 60mg for 1 dose, then 5mg once daily usually for up to 12 months.

Adult 18–74 years (body-weight 60kg and above)
Initially 60mg for 1 dose, then 10mg once daily usually for up to 12 months.

Adult 75 years and over
Initially 60mg for 1 dose, then 5mg once daily usually for up to 12 months.

Aged 75 and older - consider whether person’s risk of bleeding with prasugrel outweighs effectiveness, in which case offer ticagrelor or clopidogrel as alternatives.

(ii) Secondary prevention in cerebrovascular disease, peripheral arterial disease or multivascular disease

ChoiceDrugDosage
1st choiceClopidogrel 75mg tabletsSecondary 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 NG185 Acute Coronary Syndromes (ACS).
  • There is no conclusive evidence that enteric-coated (e/c) preparations of aspirin are better tolerated. Therefore the e/c 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.
  • Secondary prevention drug treatments are initiated in hospital after an acute myocardial infarction (MI). Dual antiplatelet therapy (DAPT) with aspirin plus a second antiplatelet is offered (unless contraindicated) and continued for up to 12 months after an MI). After DAPT, treatment with aspirin is usually continued indefinitely (unless the person is aspirin intolerant or has an indication for anticoagulation).
  • The combination of anticoagulant and antiplatelet therapy is sometimes used in selected patients, where an indication for anticoagulation co-exists, e.g. atrial fibrillation. 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 NG185 Acute Coronary Syndromes.
  • 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 to 21 days, at which point patients should continue with single antiplatelet therapy (usually clopidogrel). For further details see CKS.
  • 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 or pantoprazole are preferred to omeprazole or esomeprazole See MHRA.
  • Ticagrelor, co-administered with aspirin, is indicated for the prevention of atherothrombotic events in adult patients with acute coronary syndromes (ACS) for up to 12 months. Extended treatment with ticagrelor (following an initial 12 months course for ACS) is an option in those who have a history of MI and who are deemed to be at high risk of a future atherothrombotic event. Refer to BNF or CKS for dosing regimens.
  • 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)
  • Extended treatment is most clinically effective if it commences immediately after the initial course rather than after a gap in treatment. However it can be started within 1 year of stopping previous P2Y12 inhibitor 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
  • Guidance on the management of dental patients taking anticoagulants or antiplatelet drugs by the Scottish Dental Clinical Effectiveness Programme (SDECP) has been adopted for use in Northern Ireland and is available at sdcep.org.uk.
  • The HSC Cardiology Network has issued Post-Coronary Stenting information for staff and patients:

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.
  • Dyspnoea has been associated with the use of ticagrelor. If this is intolerable to the patient it is important to discuss treatment options with the Cardiologist as switching therapies may require reloading.

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