Ticlopidine

Ticlopidine is an oral thienopyridine antiplatelet medication used to reduce thrombotic events in patients with a history of stroke or transient ischemic attack (TIA). It is a prodrug that is converted in the liver to active thiol metabolites, which irreversibly inhibit the P2Y12 receptor on platelets. This prevents ADP-induced platelet activation and aggregation, thereby lowering the risk of arterial clot formation. The antiplatelet effect lasts for the life of the platelet, typically about 7 to 10 days.

Ticlopidine is primarily used for stroke and TIA prevention, especially in patients who cannot take aspirin or in whom combination therapy is considered. It has also been used in certain settings after cerebrovascular events or during vascular procedures. Its use has declined due to safety concerns and the availability of alternatives with more favorable risk profiles.

Dosing is oral, with regimens historically around 250 mg twice daily (taken with meals). The onset of maximum antiplatelet effect is gradual, and full protection accrues over days to weeks. It is not generally used for acute coronary syndromes because of its slower onset relative to other antiplatelet agents.

Adverse effects are notable for hematologic toxicity, including neutropenia and agranulocytosis, as well as thrombotic thrombocytopenic purpura, rash, dyspepsia, and liver enzyme elevations. Bleeding risk is increased, and regular monitoring of blood counts is required, especially during the first months of therapy. Caution is advised in patients with liver disease, renal impairment, elderly individuals, and those taking other anticoagulants or NSAIDs.

Due to safety concerns, ticlopidine has largely been replaced by clopidogrel and other P2Y12 inhibitors in modern practice, though it remains of historical importance and may be used in specific cases where alternatives are unsuitable.