Aspirin Responsiveness in Unstable Angina Pectoris: A Study on Whole Blood Aggregometry

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Scientists in Chongqing, People's Republic of China, conducted a study to evaluate aspirin responsiveness in patients with unstable angina pectoris (UAP) using whole blood aggregometry. The researchers aimed to differentiate aspirin-resistant patients into pharmacokinetic or pharmacodynamic type. They measured platelet aggregation in 70 normal volunteers and 104 UAP patients on aspirin (100 mg/day) for 7 days. The study found that aspirin resistance was observed in 36.5% of patients when using collagen at low concentration (1 μg/ml) as the inducing condition.

Key Takeaways:

  • The study found that 36.5% of patients with unstable angina pectoris (UAP) were aspirin-resistant when using collagen at low concentration (1 μg/ml) as the inducing condition.
  • Among the 38 aspirin-resistant patients, three showed normal platelet aggregation and were classified into pharmacodynamic type.
  • The researchers concluded that most aspirin 'resistance' in UAP patients is due to pharmacokinetic issues.
  • The study suggests that collagen at low concentration (1 μg/ml) is the preferred inducing condition for detecting aspirin inhibitory effect.
  • Aspirin resistance was observed in 49.0%, 64.4%, and 64.4% of patients when using 2 μg/ml collagen, 5 μmol/l adenosine diphosphate (ADP), and 10 μmol/l ADP as the inducing conditions, respectively.

Statistics:

  • 36.5% of patients with UAP were aspirin-resistant when using collagen at low concentration (1 μg/ml) as the inducing condition.
  • 3 out of 38 aspirin-resistant patients were classified into pharmacodynamic type.
  • Number of patients: 104 (UAP patients on aspirin) + 70 (normal volunteers) = 174.
  • Aspirin dose: 100 mg/day for 7 days.
  • Inducing conditions: 1 μg/ml collagen, 2 μg/ml collagen, 5 μmol/l adenosine diphosphate (ADP), and 10 μmol/l ADP.
  • Prevalence of aspirin resistance: 36.5% (using collagen at low concentration).
  • Sensitivity coefficient: suggests collagen at low concentration (1 μg/ml) is the preferred inducing condition.

Sources:

  • Li, J.B., et al. (2009). Responsiveness to aspirin in patients with unstable angina pectoris by whole blood aggregometry. International Journal of Clinical Practice, 63(3), 407-416.
  • Third Military Medical University, Xinqiao Hospital, Institute Cardiovascular Science, 183 Xinqiao St., Chongqing 400037, People's Republic of China.
  • Wiley-Blackwell Publishing, Inc., Commerce Place, 350 Main St., Malden 02148, MA, USA.