Antithrombotic drugs for secondary stroke prophylaxis.

Stroke is the third most common cause of adult mortality in the United States. Antithrombotic agents form the mainstay of stroke prevention. Aspirin produces a modest reduction in the risk of second stroke and is widely recommended for initial therapy. The thienopyridines ticlopidine and clopidogrel are alternatives for secondary prevention in patients who do not respond to or cannot take aspirin. They are no more effective than aspirin and have been associated with thrombotic thrombocytopenic purpura. The combination of aspirin and extended-release dipyridamole has several mechanisms of action and an additive effect on reducing stroke risk compared with either agent alone. A 2-fold increase in risk reduction and favorable safety profile suggest that the combination can serve as first-line prophylaxis against a second stroke.