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Updated: Jul 10, 2026

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms
08:46

Implementation of In Vitro Drug Resistance Assays: Maximizing the Potential for Uncovering Clinically Relevant Resistance Mechanisms

Published on: December 9, 2015

Aspirin and clopidogrel resistance

Desmond J Fitzgerald1, Andrew Maree

  • 1UCD Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin 4, Ireland. des.fitzgerald@ucd.ie

Hematology. American Society of Hematology. Education Program
|November 21, 2007
PubMed

Insights

Aspirin and clopidogrel offer cardiovascular benefits, but variable responses, not true resistance, explain differing therapeutic effects. Understanding these variations is key for optimizing patient treatment.

Area of Science:

  • Cardiovascular Medicine
  • Pharmacology
  • Hematology

Background:

  • Aspirin and clopidogrel are crucial for managing cardiovascular disease.
  • Platelet activation complexity leads to some cardiovascular events despite antiplatelet therapy.
  • The concepts of aspirin and clopidogrel 'resistance' are prevalent but potentially misleading.

Purpose of the Study:

  • To clarify the nature of variable responses to aspirin and clopidogrel.
  • To differentiate between true drug resistance and other factors influencing therapeutic efficacy.
  • To discuss the clinical significance of observed variations in antiplatelet drug response.

Main Methods:

  • Review of existing literature on aspirin and clopidogrel efficacy and response variability.
  • Analysis of definitions and assays used to assess antiplatelet 'resistance'.
  • Examination of pharmacological and pharmacokinetic factors influencing drug response.

Main Results:

  • Observed 'resistance' varies significantly based on the definition and measurement assay used.
  • True aspirin resistance involves reduced cyclooxygenase-1 sensitivity, though its clinical impact is unclear.
  • Clopidogrel response variability is primarily linked to active metabolite bioavailability, not receptor resistance.

Conclusions:

  • The terms 'aspirin resistance' and 'clopidogrel resistance' are often misnomers for variable drug responses.
  • Understanding individual drug pharmacology and pharmacokinetics is essential for interpreting response variations.
  • Further research is needed to establish the clinical significance of these variable responses in cardiovascular patients.

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