Antiplatelet drugs decrease platelet aggregation and may inhibit thrombus formation in the arterial circulation, where anticoagulants have little effect.
Aspirin:
Indications: prophylaxis of cerebrovascular disease or myocardial infarction. Contraindications: use other than as an antiplatelet in children and adolescents under 16 years (Reye’s syndrome); active peptic ulceration; haemophilia and other bleeding disorders; breast-feeding.
Dose and Administration: once daily
Dipyridamol:
Indications: indicated as an adjunct to coumarin anticoagulants in the prevention of postoperative thromboembolic complications of cardiac valve replacement.
Contraindications: Hypersensitivity to dipyridamole and any of the other components.
Dose and Administration: By mouth, 300–600 mg daily in 3–4 divided doses before food. By intravenous injection, diagnostic only.
Clopidogrel:
Indications: prevention of atherosclerotic events in peripheral arterial disease, or within 35 days of myocardial infarction, or within 6 months of ischaemic stroke; prevention of artherosclerotic events in acute coronary syndrome without ST-segment elevation and in acute myocardial infarction with ST-segment elevation.
Contraindications: active bleeding, breast-feeding.
Dose and Administration: Prevention of artherosclerotic events in peripheral arterial disease or after myocardial infarction or ischaemic stroke, 75 mg once daily. Acute coronary syndrome (without ST-segment elevation), initially 300 mg then 75 mg daily. Acute myocardial infarction (with ST-segment elevation), initially 300 mg then 75 mg daily; initial dose omitted if patient over 75 years.
Tirofiban:
Indications: prevention of early myocardial infarction in patients with unstable angina or non-ST-segment-elevation myocardial infarction and with last episode of chest pain within 12 hours.
Contraindications: abnormal bleeding within 30 days, stroke within 30 days or any history of haemorrhagic stroke, intracranial disease (aneurysm, neoplasm or arteriovenous malformation), severe hypertension, haemorrhagic diathesis, increased prothrombin time or INR, thrombocytopenia; breast-feeding.
Dose and Administration: By intravenous infusion, initially 400 nanograms/kg/minute for 30 minutes, then 100 nanograms/kg/minute for at least 48 hours (continue during and for 12–24 hours after percutaneous coronary intervention); max. duration of treatment 108 hours.
