Randomized trials showed greater stroke prevention with extended release dipyridamole in combination with low dose aspirin than with either aspirin or dipyridamole alone. However, most studies with this formulation (Aggrenox®) were carried out in Europe and North America. Considering potential inter-racial differences in drug response, we conducted a small randomized study in healthy Japanese volunteers to compare antiplatelet regimens with regard to the changes in the platelet biomarkers. Thirty healthy volunteers (18-40 years old, 15 male and 15 female) of Japanese descent were randomized toAggrenox (n=17) or aspirin 81 mg (n=13 volunteers) for 30 days. Platelet function was assessed at baseline, and on days 15, and 30 by conventional aggregometry, whole blood flow cytometry, and cartridge-based analyzer. Both Aggrenox and aspirin provided sustained platelet inhibition at Day 15 and Day 30.Therapy with Aggrenox, however, was associated with more prominent and significant inhibition of collagen-induced aggregation (p=0.08, Day 15),as well as prolongation of the closure time (p=0.001, Day 30); diminished expression of platelet endothelial cell adhesion molecule-1 (PECAM-1) (p=0.02, Day 30), glycoprotein IIb (GPIIb) antigen (p=0.00 I and 0.024 for Day 15 and Day 30), and GPIIb/IIIa activity by PAC- I antibody (p = 0.0 14 and 0.03), CD62 (P-selectin) (p = 0.03 for Day 15 and Day 30), as well as inhibition of protease activated receptors (PAR- I) associated with intact WEDE- 15 (p = 0.002 and 0.003) and SPAN- 12 (p = 0.002 and 0.04) thrombin receptors when compared with aspirin.The magnitude and durability of platelet response after Aggrenox in healthy Japanese is similar to those effects observed in Caucasians and African-Americans. A larger study to assess drug efficacy and safety in the Japanese post-stroke patients is warranted.
- Randomized trials
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