EFFECTS OF ASPIRIN ON PLATELET-AGGREGATION IN SMOKERS AND NONSMOKERS

OBJECTIVE: TO assess the relative antiaggregatory ability of aspirin o n platelets of smoking and nonsmoking healthy volunteers. DESIGN: Pros pective, randomized, crossover study. SETTING: Tertiary-care teaching institution. SUBJECTS: Eighteen healthy smoking and nonsmoking male vo lunteers. INTERVENTIONS: Each subject received aspirin 325 mg or ticlo pidine 250 mg bid as an active control for 7 days in a crossover manne r separated by a 1-month washout period. Whole blood platelet aggregat ion was measured on four occasions, twice at baseline and once after e ach drug treatment. OUTCOME MEASUREMENT: Whole blood ex vivo platelet aggregation in terms of impedance (Omega) and adenosine triphosphate ( ATP) release (nmol), as assessed using Lumi-aggregometry. RESULTS: Asp irin was associated with significantly less ATP release in both smoker s (p = 0.01) and nonsmokers (p = 0.003). No significant differences in platelet aggregation were found between smokers and nonsmokers at bas eline or with any treatment phases. Sixty-seven percent and 17% of vol unteers receiving ticlopidine and aspirin, respectively, reported adve rse effects. CONCLUSIONS: Twice-daily administration of aspirin for 7 days to healthy volunteers was well tolerated and also reduced platele t aggregation significantly regardless of smoking status.