Individual dosing of ASA prophylaxis by controlling platelet aggregation

Acetylsalicylic acid is widely used in the primary and secondary prevention of cardiovascular diseases. In the current study, we used platelet aggrega tion ex vivo in platelet-rich plasma induced with arachidonic acid as a rou tine method for the determination of the individual dose of acetylsalicylic acid necessary to inhibit platelet aggregation in 108 patients with cardio vascular diseases. In 40% of all patients studied, a dose of 30 mg/day was sufficient to block the arachidonic acid-induced platelet aggregation nearl y completely. In 50% of all patients, a dose of 100 mg/day was necessary. I n 10% of all patients, the dose had to be further increased to 300 mg/day o r even to 500 mg/day to inhibit platelet aggregation nearly completely. The se results demonstrate that platelet aggregation can be used as a simple ro utine laboratory method to control acetylsalicylic acid treatment in patien ts with cardiovascular diseases and to determine individual doses of acetyl salicylic acid for a nearly complete inhibition of platelet aggregation. Wi th a standard dose of 100 mg/day, 10% of the patients were nonresponders.