Piracetam has been shown to inhibit platelet aggregation. Therefore, we performed a double-blind, randomized, parallel group study to compare the efficacy of daily 1600 mg
piracetam t.i.d. vs. 200 mg
acetylsalicylic acid (ASA) t.i.d. in secondary
stroke prophylaxis. 563 patients after
stroke as confirmed by computed tomography (CT) or magnetic resonance imaging (MRI) were enrolled and received either
piracetam or ASA during a 2 year follow-up period. The primary endpoint was the rate of
stroke, transient ischaemic attack (TIA), or death from vascular cause. The secondary endpoint was the rate of adverse events leading to a premature discontinuation of the study medication. Patients were visited at home every 3 months and were examined in hospital after 1 and 2 years. At every visit, the platelet function was evaluated. No significant difference and no significant equivalence could be shown for the primary endpoint between the
piracetam and the ASA group both in the intention-to-treat and in the per-protocol analysis. However, there was a not significant trend in favor of ASA (11.7 vs. 15.2%). After excluding those patients who did not respond to antiplatelet medication in vitro, however,
piracetam and ASA were equivalent in secondary
stroke prophylaxis (
stroke, TIA, or vascular death 10.1% in the
piracetam group vs. 9.7% in the ASA group).
Piracetam was significantly superior to ASA in the secondary endpoint (P=0.0039). The data suggest that the overall efficacy of
piracetam in secondary
stroke prophylaxis is not as good as that of ASA but that
piracetam is better tolerated. However, our data furthermore show that nonresponders to pharmacological inhibition of platelet function are more frequent under
piracetam therapy and that they may influence the results of large studies on secondary prophylaxis in
vascular diseases.