Inhibition of platelet aggregation by aspirin progressively decreases in long-term treated patients

Fabio M. Pulcinelli, Pasquale Pignatelli, Andrea Celestini, Silvia Riondino, Pier Paolo Gazzaniga, Francesco Violi

Research output: Contribution to journalArticlepeer-review


Objectives We sought to investigate, during a two-year follow-up period, the effects of aspirin on platelet aggregation. Background The platelets of patients given aspirin may be less sensitive to antiplatelet treatment, although the extent of such phenomenon over long-term follow-up is unclear. Methods Adenosine diphosphate (ADP) and collagen-induced platelet aggregation was periodically monitored before and after 2, 6, 12, and 24 months of treatment with aspirin (n = 150) or ticlopidine (n = 80) in patients matched for gender, age, and risk factors for atherothrombosis. Results Compared with baseline values, two months of aspirin treatment significantly inhibited platelet aggregation; thereafter, this inhibitory effect progressively decreased. At 24-month follow-up, collagen-induced platelet aggregation was significantly higher than that observed at two months (p <0.05); a more pronounced difference was observed when collagen-induced lag phase was considered (p <0.01). Restoration of platelet aggregation was less evident when ADP was used as an agonist. Conversely, the inhibition induced by ticlopidine was constant throughout follow-up with both agonists. Conclusions The study demonstrates that a long-term treatment with aspirin is associated with a progressive reduction in platelet sensitivity to this drug.

Original languageEnglish
Pages (from-to)979-984
Number of pages6
JournalJournal of the American College of Cardiology
Issue number6
Publication statusPublished - Mar 17 2004


  • Adenosine diphosphate
  • ADP
  • COX-1
  • Cyclooxygenase-1
  • Maximal percentage
  • Mx%
  • Thromboxane A
  • Thromboxane B
  • TXA
  • TXB

ASJC Scopus subject areas

  • Nursing(all)


Dive into the research topics of 'Inhibition of platelet aggregation by aspirin progressively decreases in long-term treated patients'. Together they form a unique fingerprint.

Cite this