Ribofan

Indications

• Myocardial ischaemia
• Unstable angina
• ST-segment elevation myocardial infarction (STEMI)
• Adjunct to percutaneous coronary intervention (PCI)

Dosage

Adults: Initial intravenous injection of 25 micrograms/kg over 3 minutes, followed by a continuous infusion of 0.15 micrograms/kg/min for 12 to 24 hours, with a maximum duration of treatment of 48 hours. If creatinine clearance is 30-50 mL/min, the infusion rate should be reduced to 1 microgram/kg/min.

Mechanism of action

Tirofiban functions as a reversible antagonist of fibrinogen binding to the GP IIb/IIIa receptor, a key platelet surface receptor that mediates platelet aggregation. By binding to this receptor, tirofiban inhibits the binding of fibrinogen, which is essential for platelet aggregation. This inhibition is dose- and concentration-dependent and is reversible upon cessation of the drug infusion.

Pharmacodynamics

Tirofiban prevents clot formation during episodes of acute coronary syndromes, such as chest pain or heart attacks, and during procedures aimed at treating blocked coronary arteries. It is a non-peptide antagonist of the GP IIb/IIIa receptor, achieving greater than 90% inhibition of platelet aggregation within 30 minutes of administration when dosed as recommended. This significant inhibition contributes to a reduced incidence of ischemic events in patients with unstable angina compared to standard heparin therapy.

Pharmacokinetics

Tirofiban is administered intravenously, and its pharmacokinetics involve rapid distribution and elimination. The onset of action occurs swiftly due to direct infusion into the bloodstream, with a half-life that allows for rapid adjustment of dosage based on patient response. It is primarily eliminated by renal pathways, and caution is advised in patients with renal impairment, necessitating dose adjustments.

Contra-indications

• Active peptic ulcer (within 3 months)
• Severe bleeding disorders
• Severe hypertension
• Uncontrolled severe hypertension
• Recent major surgery or trauma (within 3 months)
• Intracranial hemorrhage
• Traumatic or protracted cardiopulmonary resuscitation within last 2 weeks

Adverse effects

• Hemorrhage
• Thrombocytopenia
• Arrhythmias
• Cardiac arrest
• Congestive heart failure
• Hypotension
• Rash
• Cerebral ischemia
• Headache
• Nausea

Interactions

• Anticoagulants (e.g., heparin, warfarin) may increase bleeding risk
• Aspirin may enhance the antiplatelet effect
• Clopidogrel may be used in combination but should be monitored for bleeding

Precautions

• Caution in patients with renal impairment
• Caution in patients with a history of bleeding disorders
• Monitor for signs of bleeding during and after treatment
• Consider risk of thrombocytopenia with prolonged use

Pregnancy

Manufacturer advises use only if potential benefit outweighs risk-no information available.

Breast-feeding

Manufacturer advises avoid-no information available.

Storage

Store below 25°C. Protect from light. Do not freeze.

Formulations

• Tirofiban 25 micrograms/kg solution for injection
• Tirofiban 75 mg/100 ml solution for infusion

Mechanism of action

Tirofiban is a reversible antagonist of fibrinogen binding to the GP IIb/IIIa receptor, the major platelet surface receptor involved in platelet aggregation. Platelet aggregation inhibition is reversible following cessation of the infusion of tirofiban. Tirofiban inhibits platelet aggregation by reversibly binding to the platelet receptor glycoprotein (GP) IIb/IIIa of human platelets, thus preventing the binding of fibrinogen. Inhibition of platelet aggregation occurs in a dose- and concentration-dependent manner.

Pharmacodynamics

Tirofiban prevents the blood from clotting during episodes of chest pain or a heart attack, or while the patient is undergoing a procedure to treat a blocked coronary artery. It is a non-peptide antagonist of the platelet glycoprotein (GP) IIb/IIIa receptor, and inhibits platelet aggregation. When administered intravenously, tirofiban inhibits ex vivo platelet aggregation in a dose- and concentration-dependent manner. When given according to the recommended regimen, >90% inhibition is attained by the end of the 30-minute infusion. Tirofiban has been recently shown in patients with unstable angina to reduce ischemic events at 48 hours following infusion when compared to standard heparin therapy.