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Aspirin response and failure in cerebral infarction
C M Helgason1, K L Tortorice, S R Winkler
1Department of Neurology, University of Illinois, Chicago College of Medicine 60612.
Insights
Aspirin dose impacts platelet aggregation inhibition, crucial for stroke prevention. Individual responses vary, with some patients showing aspirin resistance even at higher doses.
Area of Science:
- Pharmacology
- Cardiovascular Medicine
- Neurology
Background:
- Platelet aggregation inhibition is a key mechanism for aspirin's effectiveness in stroke prevention.
- Understanding individual responses to aspirin is vital for optimizing treatment.
Purpose of the Study:
- To evaluate the biological effect of aspirin by measuring platelet aggregation inhibition.
- To compare aspirin's effects in patients undergoing stroke prevention versus those with acute stroke.
Main Methods:
- Administered escalating doses of aspirin (325-1300 mg daily) to 113 patients for stroke prevention.
- Measured platelet aggregation inhibition in these patients and in 33 acute stroke patients pre-treatment.
Main Results:
- Complete platelet aggregation inhibition was achieved in most patients at doses up to 650 mg.
- Aspirin resistance (partial inhibition) was observed in some patients, even at 1300 mg.
- Similar patterns of inhibition and resistance were noted in acute stroke patients.
Conclusions:
- The precise relationship between platelet aggregation inhibition and stroke prevention efficacy requires further investigation.
- Individual variability in response to aspirin, including dose requirements and resistance, is significant.
Background And Purpose:
The purpose of this study was to assess the biological effect of aspirin as measured by the inhibition of platelet aggregation in patients taking aspirin for stroke prevention and in patients with acute stroke.
Methods:
We administered increasing doses of aspirin (325, 650, 975, and 1,300 mg daily) to 113 patients for stroke prevention and measured the inhibition of platelet aggregation in these patients and in 33 patients with acute stroke taking aspirin before stroke onset.
Results:
Eighty-five patients on < or = 325 and six on > or = 650 mg aspirin had complete inhibition of platelet aggregation. Increase of the dose by 325 mg in nine of the 22 patients with partial inhibition of platelet aggregation produced complete inhibition in five patients at 650 mg and in one at 975 mg. At 1,300 mg, three patients still had only partial inhibition of platelet aggregation (aspirin resistance). Of the 33 inpatients with acute stroke, 24 had platelet aggregation studies done before further administration of aspirin. Of these, 19 had complete inhibition of platelet aggregation and three had partial inhibition, with production of complete inhibition of platelet aggregation at dose escalation; one patient was aspirin-resistant and the other noncompliant.
Conclusions:
How the inhibition of platelet aggregation relates to stroke prevention remains unclear. The ability of aspirin and the dose required to inhibit platelet aggregation may depend upon the individual.