Compared with aspirin , thienopyridines significantly reduced gastrointestinal adverse effects .
However , thienopyridines increased the odds of skin rash and diarrhoea , ticlopidine more than clopidogrel .
Allocation to ticlopidine , but not clopidogrel , significantly increased the odds of neutropenia .
The thienopyridine derivatives are at least as effective as aspirin in preventing serious vascular events in patients at high risk , and possibly somewhat more so .
However , the size of any additional benefit is uncertain and could be negligible .
Clopidogrel has a more favourable adverse effects profile than ticlopidine and so is the thienopyridine of choice .
BACKGROUND Aspirin is the most widely studied and prescribed antiplatelet agent for preventing serious vascular events , reducing the odds of such events among high vascular risk patients by about a quarter .
Thienopyridine derivatives inhibit platelet activation by a different mechanism and so may be more effective .
OBJECTIVES To determine the effectiveness and safety of thienopyridine derivatives ( ticlopidine and clopidogrel ) versus aspirin for preventing serious vascular events ( stroke , myocardial infa rct ion ( MI ) or vascular death ) in patients at high risk , and specifically in patients with a previous TIA or ischaemic stroke .
Unstable angina, stroke, myocardial infarction and death in aspirin non‐responders. A prospective, randomized trial. The ASCET (ASpirin non‐responsiveness and Clopidogrel Endpoint Trial) design
Background —Aspirin is widely used as an antiplatelet drug in patients with coronary heart disease . Despite documented clinical benefit , many patients on aspirin  still experience severe cardiovascular events . Several laboratory reports have shown lack of platelet inhibition in 5–40 % of aspirin‐treated patients , and the term aspirin resistance has been introduced . The clinical relevance of these laboratory findings is , however , still unknown . New antiplatelet drugs have been developed , and the adenosin diphosphate ( ADP ) receptor inhibitor clopidogrel has at least the same efficacy as aspirin with an acceptable safety profile . Laboratory methods for determination of platelet reactivity and treatment efficacy have been complicated and time consuming . New method ologies , like the PFA‐100 ® system , have made such analyses more suitable for clinical use . Design —In the ASCET study , 1000 patients with documented coronary heart disease will be r and omized to either continued treatment with aspirin 160 mg/d or change to clopidogrel 75 mg/d after initial determination of their platelet reactivity while on aspirin treatment . Clinical endpoints will be recorded for at least 2 years and related to the initial aspirin response
Compared with aspirin , thienopyridines significantly reduced gastrointestinal adverse effects .
However , thienopyridines increased the odds of skin rash and diarrhoea , ticlopidine more than clopidogrel .
Allocation to ticlopidine , but not clopidogrel , significantly increased the odds of neutropenia .
The thienopyridine derivatives are at least as effective as aspirin in preventing serious vascular events in patients at high risk , and possibly somewhat more so .
However , the size of any additional benefit is uncertain and could be negligible .
Clopidogrel has a more favourable adverse effects profile than ticlopidine and so is the thienopyridine of choice .
BACKGROUND Aspirin is the most widely studied and prescribed antiplatelet agent for preventing serious vascular events , reducing the odds of such events among high vascular risk patients by about a quarter .
Thienopyridine derivatives inhibit platelet activation by a different mechanism and so may be more effective .
OBJECTIVES To determine the effectiveness and safety of thienopyridine derivatives ( ticlopidine and clopidogrel ) versus aspirin for preventing serious vascular events ( stroke , myocardial infa rct ion ( MI ) or vascular death ) in patients at high risk , and specifically in patients with a previous TIA or ischaemic stroke .