3 The technologies
3.1 Clopidogrel (Plavix, Sanofi-Aventis, Bristol-Myers Squibb) is an irreversible adenosine diphosphate-receptor antagonist with antiplatelet properties. Clopidogrel is available as branded and generic preparations and has a marketing authorisation for 'the prevention of atherothrombotic events in patients suffering from myocardial infarction (from a few days until less than 35 days), ischaemic stroke (from 7 days until less than 6 months) or established peripheral arterial disease'.
3.2 Contraindications to clopidogrel include severe liver impairment and active pathological bleeding such as peptic ulcer or intracranial haemorrhage. For full details of side effects and contraindications, see the summary of product characteristics.
3.3 The cost of branded clopidogrel for 30 days at a dose of 75 mg daily is £35.64 per person (British national formulary [BNF], edition 60). The cost of generic clopidogrel 75 mg in the NHS Drug Tariff (October 2010) is £3.40 for 30 days. Costs may vary in different settings because of negotiated procurement discounts.
3.4 Modified-release dipyridamole (Persantin Retard and Asasantin Retard, Boehringer Ingelheim) has both antiplatelet and vasodilating properties and is thought to inhibit the uptake of adenosine into blood and vascular cells. Dipyridamole may also inhibit the breakdown of cyclic guanosine monophosphate. Modified-release dipyridamole has a marketing authorisation for the 'secondary prevention of ischaemic stroke and transient ischaemic attacks either alone or in conjunction with aspirin'. It is available either on its own as Persantin Retard, or in a combination tablet with aspirin as Asasantin Retard.
3.5 Dipyridamole has activity as a vasodilator; therefore it should be used with caution in people with severe coronary artery disease, including unstable angina and/or recent myocardial infarction, left ventricular outflow obstruction or haemodynamic instability (for example, decompensated heart failure). For full details of side effects and contraindications, see the summary of product characteristics.
3.6 The cost of treatment for 30 days with modified-release dipyridamole alone is £7.50 and modified-release dipyridamole plus aspirin is £7.79 per person (BNF, edition 60). Costs may vary in different settings because of negotiated procurement discounts.