tirofiban
Summary
Tirofiban is a non-peptide glycoprotein IIb/IIIa receptor antagonist used as an antiplatelet agent in acute coronary syndromes. It reversibly blocks the final common pathway of platelet aggregation by preventing fibrinogen binding to activated platelets.
Detail
Tirofiban is a reversible, competitive antagonist of the glycoprotein IIb/IIIa receptor on platelets. The GP IIb/IIIa receptor is the final common pathway for platelet aggregation, regardless of the initial stimulus (ADP, thrombin, collagen, etc.). When platelets are activated, this receptor undergoes conformational changes that allow it to bind fibrinogen and von Willebrand factor, leading to platelet cross-linking and clot formation. Tirofiban blocks this binding, preventing platelet aggregation. It is administered intravenously and has a short half-life (approximately 2 hours), with platelet function returning to normal within 4-8 hours after discontinuation. Clinically, it's used in high-risk acute coronary syndromes (unstable angina/NSTEMI) and during percutaneous coronary interventions (PCI) to reduce thrombotic complications. The primary risk is bleeding, including thrombocytopenia (occurs in 1-2% of patients). Unlike abciximab, tirofiban is reversible and has a lower immunogenicity profile. It's contraindicated in patients with active bleeding, severe hypertension, or recent surgery/trauma.
Sources
- Goodman & Gilman's The Pharmacological Basis of Therapeutics
- Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine
- Basic & Clinical Pharmacology by Katzung
- First Aid for the USMLE Step 1
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