Which antiplatelet drug is administered intravenously?

Tirofiban is an antiplatelet drug that is administered intravenously. It is a platelet glycoprotein IIb/IIIa inhibitor, which means it works by blocking the binding of fibrinogen and other adhesive molecules to platelets, thus preventing platelet aggregation. This mechanism makes it particularly effective in the acute management of patients with unstable angina or those undergoing percutaneous coronary interventions, where rapid and potent antiplatelet effects are desired. The intravenous route allows for immediate bioavailability and quick action during critical situations in the hospital setting.

The other options listed do not require intravenous administration. Vorapaxar, for instance, is an oral antiplatelet medication that acts by inhibiting the protease-activated receptor-1 (PAR-1) on platelets. Cilostazol is also administered orally and has mechanisms that involve vasodilation and inhibition of platelet aggregation. Aspirin, while a commonly used antiplatelet agent, is usually given orally in various formulations. Thus, Tirofiban is uniquely positioned as the only intravenous option among the choices provided.