Clopidogrel-induced platelet inhibition cannot be detected by the platelet function analyzer-100 system in stroke patients

J Stroke Cerebrovasc Dis. 2007 Sep-Oct;16(5):199-202. doi: 10.1016/j.jstrokecerebrovasdis.2007.05.001.

Abstract

The administration of an adenosine diphosphate (ADP) receptor antagonist, such as clopidogrel, is recommended for recurrent stroke patients under aspirin treatment. However, up to 25% of vascular patients have an inadequate response to clopidogrel treatment, which could be associated with increased reinfarction rates. This study investigated whether the platelet function analyzer (PFA-100) system represents an appropriate tool for monitoring clopidogrel's antiplatelet effects in stroke patients. Sixteen stroke patients on clopidogrel therapy (75 mg/day) were included in a prospective analyst-blinded, cross-sectional study. Platelet function was assayed by collagen/epinephrine (CEPI)- and collagen/ADP (CADP)-induced closure times (CTs) using the PFA-100 system. von Willebrand factor antigen (vWF-Ag) levels were measured by enzyme immunoassay. CEPI-CT and CADP-CT values averaged 160 +/- 15 seconds and 102 +/- 10 seconds, respectively, and were in the normal range. vWF-Ag concentrations averaged 153 +/- 17% and correlated inversely with CTs (r = .71; P < .002 for CEPI-CT, r = .54; P < .04 for CADP-CT). Our data indicate that the current PFA-100 cartridges are not sufficiently sensitive to detect clopidogrel-induced platelet inhibition in stroke patients.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenosine Diphosphate
  • Aged
  • Bleeding Time / instrumentation*
  • Clopidogrel
  • Collagen
  • Cross-Sectional Studies
  • Drug Monitoring / instrumentation*
  • Drug Monitoring / methods
  • Drug Resistance*
  • Epinephrine
  • Female
  • Hematocrit
  • Humans
  • Male
  • Middle Aged
  • Platelet Aggregation / drug effects*
  • Platelet Aggregation Inhibitors / pharmacology
  • Platelet Aggregation Inhibitors / therapeutic use*
  • Prospective Studies
  • Reproducibility of Results
  • Secondary Prevention
  • Stroke / blood
  • Stroke / drug therapy*
  • Ticlopidine / analogs & derivatives*
  • Ticlopidine / pharmacology
  • Ticlopidine / therapeutic use
  • Time Factors
  • von Willebrand Factor / metabolism

Substances

  • Platelet Aggregation Inhibitors
  • von Willebrand Factor
  • Adenosine Diphosphate
  • Collagen
  • Clopidogrel
  • Ticlopidine
  • Epinephrine