Ticlopidine: a new antiplatelet agent for cerebrovascular disease.

Ticlopidine is a new prototype antiplatelet drug chemically unrelated to currently available agents. It causes an alteration in platelet membrane reactivity to a variety of aggregating stimuli and a marked prolongation of bleeding time, the mechanism of which remains unclear. Two major phase III multicenter trials, the ticlopidine-aspirin stroke study (TASS) and the Canadian-American ticlopidine study (CATS) reported that the agent may reduce the occurrence of stroke, myocardial infarction, or vascular death in patients of both sexes who have had recent cerebral ischemia. Ticlopidine has been well tolerated in preliminary studies, with the most commonly described adverse effects being rash and gastrointestinal complaints. The most important adverse effect is neutropenia, which was reported in both TASS and CATS, approximating a frequency of 0.9% and 0.8%, respectively. Ticlopidine holds considerable promise as adjunctive therapy in selected patients.