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Biological effects of aspirin and clopidogrel in a randomized cross‐over study in 96 healthy volunteers
Author(s) -
FONTANA P.,
NOLLI S.,
REBER G.,
DE MOERLOOSE P.
Publication year - 2006
Publication title -
journal of thrombosis and haemostasis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.947
H-Index - 178
eISSN - 1538-7836
pISSN - 1538-7933
DOI - 10.1111/j.1538-7836.2006.01867.x
Subject(s) - aspirin , clopidogrel , medicine , platelet , antiplatelet drug , pharmacology , anesthesia
Summary. Background: Some data suggest that biological ‘resistance’ to aspirin or clopidogrel may influence clinical outcome. Objective: The aim of this study was to evaluate the relationship between aspirin and clopidogrel responsiveness in healthy subjects. Methods: Ninety‐six healthy subjects were randomly assigned to receive a 1‐week course of aspirin 100 mg day −1 followed by a 1‐week course of clopidogrel (300 mg on day 1, then 75 mg day −1 ), or the reverse sequence, separated by a 2‐week wash‐out period. The drug effects were assessed by means of serum TxB 2 assay, platelet aggregation tests, and the PFA ‐100 ® and Ultegra RPFA ‐ Verify Now ® methods. Results: Only one subject had true aspirin resistance, defined as a serum TxB 2 level > 80 pg μ L −1 at the end of aspirin administration and confirmed by platelet incubation with aspirin. PFA‐100 ® values were normal in 29% of the subjects after aspirin intake, despite a drastic reduction in TxB 2 production; these subjects were considered to have aspirin pseudo‐resistance. Clopidogrel responsiveness was not related to aspirin pseudo‐resistance. Selected polymorphisms of platelet receptor genes were not associated with either aspirin or clopidogrel responsiveness. Conclusions: In healthy subjects, true aspirin resistance is rare and aspirin pseudo‐resistance is not related to clopidogrel responsiveness.