Tirofiban Drug Class
Tirofiban is a glycoprotein IIb/IIIa (GP IIb/IIIa) receptor antagonist, specifically a non-peptide tyrosine derivative that reversibly inhibits platelet aggregation. 1, 2
Mechanism of Action
Tirofiban functions as a reversible antagonist of fibrinogen binding to the GP IIb/IIIa receptor, the major platelet surface receptor involved in platelet aggregation 2. This mechanism distinguishes it from other antiplatelet agents:
- Selectively binds to GP IIb/IIIa receptors to prevent fibrinogen-dependent platelet aggregation 1, 2
- Achieves >90% inhibition of platelet aggregation within 10 minutes when given as a 25 mcg/kg bolus followed by 0.15 mcg/kg/min maintenance infusion 2
- Reversibility is rapid: platelet aggregation returns to 50% of baseline within 4 hours and near-baseline within 4-8 hours after stopping the infusion 1, 2
Classification Within GP IIb/IIIa Inhibitors
Tirofiban belongs to the small molecule, non-peptide class of GP IIb/IIIa inhibitors 1. The three FDA-approved intravenous GP IIb/IIIa inhibitors differ in their molecular structure:
- Abciximab: Monoclonal antibody (large molecule)
- Tirofiban: Non-peptide tyrosine derivative (small molecule) 1, 2
- Eptifibatide: Synthetic cyclic heptapeptide (small molecule) 1
Key Pharmacologic Distinctions
Tirofiban's small molecular structure confers specific pharmacologic advantages:
- Plasma half-life: 1.5-2 hours (much shorter than abciximab) 1
- Protein binding: 35% unbound fraction, concentration-independent 2
- Clearance: Primarily renal (65% unchanged in urine), with biliary contribution (25% in feces) 1, 2
- Reversibility: High affinity for GP IIb/IIIa but dissociates much faster than abciximab, making its action reversible within hours 3
Important Clinical Caveat
Dose adjustment is mandatory in severe renal insufficiency (creatinine clearance <30 mL/min): reduce both bolus and infusion doses by 50%, as the half-life is prolonged more than threefold in this population 1, 2. Patients with renal impairment have increased bleeding risk, as demonstrated in the PRISM-PLUS trial 1.
Clinical Indication
Tirofiban is FDA-approved as a platelet aggregation inhibitor to reduce thrombotic cardiovascular events (death, myocardial infarction, or refractory ischemia/repeat cardiac procedure) in patients with non-ST elevation acute coronary syndrome (NSTE-ACS) 2.