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 .
The effect of clopidogrel, aspirin and both antiplatelet drugs on platelet function in patients with peripheral arterial disease
Peripheral arterial disease ( PAD ) is associated with platelet hyperactivity . Aspirin and clopidogrel , two platelet inhibitors , act by different mechanisms . Aspirin inhibits thromboxane A2 synthesis and clopidogrel acts on the P2Y12 platelet ADP receptor . We evaluated the effect of clopidogrel ( 75 mg/day ) , aspirin ( 75 mg/day ) and then both drugs on several platelet function indices in patients with PAD ( n = 20 ) . There was a significant ( P = 0.0001 ) decrease in ADP-induced aggregation , after clopidogrel but not after taking aspirin . Clopidogrel plus aspirin significantly decreased spontaneous platelet aggregation ( SPA ) ( P = 0.01 to P = 0.002 ) but SPA was not significantly altered by either aspirin or clopidogrel monotherapy . Similarly , monotherapy did not inhibit serotonin (5HT)-induced aggregation but there was a significant inhibition ( P = 0.03 to P<0.02 ) after combination therapy . ADP ( 0.8 μM)-induced platelet shape change ( PSC ) was significantly inhibited by clopidogrel ( P = 0.004 ) or aspirin ( P = 0.01 ) . This was also true for 5HT-induced PSC  ( clopidogrel , P = 0.01 ; aspirin , P = 0.03 ) . Soluble P-selectin decreased significantly ( from 32 ± 24 to 25 ± 17 ng/ml , P = 0.04 ) with combination therapy . Plasma platelet-derived growth factor and intraplatelet 5HT levels were not altered by combination therapy . In PAD , clopidogrel is a more potent inhibitor of ADP-induced platelet activation than aspirin ; combination therapy is more effective than clopidogrel or aspirin monotherapy . These potentially clinical ly relevant findings should be evaluated in appropriately design ed trials
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 .