Summary
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 to Aggrenox (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 withAggrenox, 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=0.001 and 0.024 for Day 15 and Day 30), and GPIIb/IIIa activity by PAC-1 antibody
(p = 0.014 and 0.03), CD62 (P-selectin) (p = 0.03 for Day 15 and Day 30), as well
as inhibition of protease activated receptors (PAR-1) 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.
Keywords
Randomized trials - aspirin - Aggrenox
Ⓡ
- dipyridamole - platelets - Japanese