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document
Effects of aspirin and clopidogrel in healthy men measured by platelet aggregation and PFA-100 . There are no generally accepted definitions for low-response ( frequently called resistance ) to the platelet inhibitors , aspirin and clopidogrel . Low-response may increase the risk of cardiovascular events in atherosclerotic patients . We aimed to define the normal drug responses in healthy men . Platelet function was measured in 20 healthy men during 11 days of aspirin or clopidogrel intake , using light transmission aggregometry ( LTA ) and the Platelet Function Analyzer 100 ( PFA-100 ) . The lower limits for LTA at baseline were 64 % and 61 % , using arachidonic acid and ADP as agonists , respectively . During aspirin intake the LTA results were stable from day to day , and an upper limit of 9 % arachidonic acid stimulated aggregation was found . Clopidogrel intake was best shown by ADP induced aggregation . However , two out of 20 individuals exhibited low-response to clopidogrel . In the remaining 18 volunteers an upper limit of 48 % aggregation was found . We found an upper limit for collagen-epinephrine stimulated PFA-100 results of 166 s at baseline . During aspirin intake , these results varied considerably from day to day in nine out of 20 men , resulting in an overlap between the reference ranges at baseline and during therapy . In conclusion , platelet inhibition by aspirin and clopidogrel assessed by aggregometry was stable during 11 days of treatment and reference ranges were established . The PFA-100 results varied greatly and low-response was not precisely defined by this method .
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Intervention_Pharmacological
aspirin
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Intervention_Pharmacological
clopidogrel
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Intervention_Pharmacological
aspirin
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Intervention_Pharmacological
clopidogrel .
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Intervention_Pharmacological
aspirin
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Intervention_Pharmacological
clopidogrel
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Intervention_Pharmacological
aspirin
37213
Intervention_Pharmacological
Clopidogrel
37214
Intervention_Pharmacological
clopidogrel
37215
Intervention_Pharmacological
aspirin
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Intervention_Pharmacological
aspirin
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Intervention_Pharmacological
clopidogrel
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Outcome_Physical
LTA results
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Outcome_Physical
arachidonic acid stimulated aggregation
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Outcome_Physical
Clopidogrel intake
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Outcome_Physical
low-response to clopidogrel .
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Outcome_Physical
collagen-epinephrine stimulated PFA-100 results
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Outcome_Physical
platelet inhibition by aspirin and clopidogrel assessed by aggregometry