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6343863 
Journal Article 
Monitoring of aspirin (ASA) pharmacodynamics with the platelet function analyzer PFA-100 
Homoncik, M; Jilma, B; Hergovich, N; Stohlawetz, P; Panzer, S; Speiser, W 
2000 
1 
Thrombosis and Haemostasis
ISSN: 0340-6245 
83 
2 
316-321 
English 
10739392 
WOS:000085440300025 
BACKGROUND: Anti-platelet drug therapy is currently performed without monitoring, because the established method of platelet aggregometry is cumbersome. The recently developed platelet function analyzer PFA-100 measures shear stress dependent, collagen epinephrine (CEPI) and collagen adenosine diphosphate (CADP) induced platelet plug formation. As the PFA-100 provides a valuable tool to detect patients with platelet dysfunction more efficiently and cost-effectively than aggregometry, we investigated its potential to monitor the efficacy of aspirin treatment.

METHODS: All healthy volunteers (n = 10) received a fractionated infusion of L-aspirin to establish individual dose-response curves. Further, in a randomized, double-blind, placebo controlled two-way cross over study the same volunteers received either 50 or 100 mg aspirin/day p.o. for a period of 11 days to determine the day-to-day variability CEPI induced closure time (CT) under constant intake of low dose aspirin, and to compare the efficacy of those two doses.

RESULTS: Intra- and intersubject variability of CEPI-CT averaged 9% and 22%, respectively. Seven volunteers exceeded the maximum of CEPI-CT (>300 s) already after infusion of 100 mg L-aspirin. Intake of 100 mg of aspirin elicited a more rapid onset of effect than 50 mg, which was only significant on days 3 and 4 of aspirin intake. The aspirin induced CEPI-CT prolongation correlated positively with basal CEPI-CT values (r = 0.86; p = 0.001) and were strongly dependent on von Willebrand Factor levels (r = -0.9; p = 0.001).

CONCLUSION: Thus, the PFA-100 system appears suitable to demonstrate an aspirin-induced platelet effect in a longitudinal study, and may be adequate to monitor a patient's compliance. However, prospective trials have to be conducted to demonstrate whether the EPI-CT achieved under ASA-intake has predictive value for cardiovascular outcome. 
Hematology; Cardiovascular System & Cardiology; aspirin, platelet function analyzer, PFA-100, alpha(2)-integrin; bleeding-time, integrin, collagen, disease, system