Eptifibatide is a synthetic, cyclic heptapeptide and a potent, reversible antagonist of the platelet glycoprotein IIb/IIIa (GPIIb/IIIa) receptor, also known as integrin αIIbβ3. It was developed based on the structure of barbourin, a protein found in the venom of the southeastern pygmy rattlesnake, which exhibits high specificity for the GPIIb/IIIa receptor over other integrins. Its discovery marked a significant advancement in antiplatelet therapy, as the GPIIb/IIIa receptor is the final common pathway for platelet aggregation, regardless of the initial agonist. Eptifibatide’s significance lies in its clinical use as an intravenous antiplatelet agent to prevent thrombotic complications in patients with acute coronary syndromes (ACS) undergoing percutaneous coronary intervention (PCI). It represents a class of drugs that provided a more targeted approach to platelet inhibition compared to earlier agents.
Quick Facts
| Also Known As | Integrilin, MK-0852, Eptifibatide Acetate |
|---|---|
| Sequence | Mpr-Har-Gly-Asp-Trp-Pro-Cys-NH2 (cyclic via disulfide bond between Mpr and Cys) |
| Molecular Formula | C35H49N11O9S2 |
| Molecular Weight | 832.0 Da |
| PubChem CID | 448812 |
Research Parameters
| Half-Life | ~2.5 hours (terminal half-life after IV administration) |
|---|---|
| Stability | Lyophilized powder is stable when stored as recommended. The commercially available injectable solution (Integrilin) is stable for 24 months when refrigerated at 2-8°C. After reconstitution or dilution in normal saline or dextrose solutions, it is stable for 12 hours at room temperature or 24 hours refrigerated. |
| Solubility | For research (lyophilized powder), reconstitution is typically performed with Sterile Water for Injection or 0.9% Sodium Chloride Injection. The commercial product is supplied as a ready-to-use or ready-to-dilute sterile solution. |
| Storage (Lyophilized) | For research-grade material: Store at -20°C, protect from light and moisture. |
| Storage (Reconstituted) | For research solutions: Store at 2-8°C for short-term use (typically within 24 hours). Do not freeze. |
| Typical Research Dose | In clinical research: Bolus of 180 mcg/kg IV, followed by continuous infusion of 2.0 mcg/kg/min. |
| Cycle Parameters | In clinical research protocols: Administered as an intravenous bolus followed by a continuous infusion for a defined period, typically 18-24 hours post-procedure. There is no 'on/off cycle' as used in chronic therapies; it is an acute, short-term intervention. |
| Amino Acid Count | 8 |
Mechanism of Action
Eptifibatide exerts its antiplatelet effect by specifically and reversibly binding to the platelet glycoprotein IIb/IIIa (GPIIb/IIIa) receptor (integrin αIIbβ3). This receptor undergoes a conformational change upon platelet activation, becoming competent to bind fibrinogen and von Willebrand factor, which cross-link adjacent platelets to form an aggregate. Eptifibatide competitively inhibits this binding, preventing the final common pathway of platelet aggregation.
Competitive Antagonism: Eptifibatide contains the Lys-Gly-Asp (KGD) sequence, a mimetic of the Arg-Gly-Asp (RGD) sequence found in fibrinogen and other adhesive proteins. It binds with high affinity and specificity to the GPIIb/IIIa receptor at or near the RGD binding site, sterically hindering the binding of fibrinogen.
Rapid Onset and Reversibility: Due to its reversible binding and short half-life, eptifibatide provides rapid and titratable platelet inhibition. Platelet function recovers within 2-4 hours after discontinuation of the infusion, which is a safety feature in case of bleeding complications.
Dose-Dependent Inhibition: The degree of platelet inhibition is directly related to plasma concentration. Therapeutic regimens aim to achieve >80% inhibition of platelet aggregation in response to agonists like ADP to effectively prevent ischemic events.
Research Applications
Cardiovascular Research: Eptifibatide is a cornerstone tool in cardiovascular research for studying platelet biology and thrombosis. It is used in ex vivo and in vivo models to dissect the role of the GPIIb/IIIa receptor in arterial thrombosis, stent thrombosis, and restenosis. Research has elucidated its efficacy in preventing acute vessel closure and ischemic complications during and after percutaneous coronary interventions.
Platelet Function and Hemostasis Studies: As a specific GPIIb/IIIa antagonist, eptifibatide is invaluable for investigating the mechanisms of platelet aggregation independent of upstream signaling pathways (e.g., ADP, thromboxane A2). It is used in flow cytometry, platelet aggregometry, and other assays to define the contribution of the final common pathway to thrombus formation under various shear conditions and disease states.
Comparative Pharmacology: Research often compares eptifibatide with other antiplatelet agents (e.g., tirofiban, abciximab, P2Y12 inhibitors) to understand differences in pharmacodynamics, reversibility, and clinical outcomes. Studies explore its potential synergistic or additive effects when combined with other antithrombotic drugs.
Safety & Side Effects
The primary safety concern from clinical studies is bleeding, ranging from minor bleeding at vascular access sites to major bleeding events such as intracranial hemorrhage. Thrombocytopenia, including severe thrombocytopenia, is a known adverse effect. Other reported side effects in clinical trials include hypotension, nausea, and headache. In animal toxicology studies, the major dose-limiting toxicity was bleeding. Theoretical concerns include the potential for hypersensitivity reactions, though these are rare. The reversible nature of its binding mitigates bleeding risk compared to irreversible inhibitors.
Dosage Information
Disclaimer: The following information is derived from published clinical and preclinical research protocols and is for research reference only. It does not constitute medical advice.
In clinical research (human trials), eptifibatide is administered exclusively via intravenous (IV) route. The typical research/clinical bolus dose is 180 mcg/kg, followed by a continuous infusion of 2.0 mcg/kg/min. For patients undergoing percutaneous coronary intervention (PCI), an additional 180 mcg/kg bolus is administered 10 minutes after the first bolus, and the infusion is continued for 18-24 hours post-procedure. The duration of infusion in studies typically ranges from 18 to 72 hours, depending on the clinical scenario (e.g., unstable angina, non-ST-elevation myocardial infarction). Dose adjustments are required for patients with renal impairment.
References
Phillips, D.R., et al. 'Effect of Ca2+ on GP IIb-IIIa interactions with integrilin: enhanced GP IIb-IIIa binding and inhibition of platelet aggregation by reductions in the concentration of ionized calcium in plasma anticoagulated with citrate.' Circulation, 1997.
Harrington, R.A., et al. 'Randomized, placebo-controlled trial of the platelet glycoprotein IIb/IIIa inhibitor eptifibatide (Integrilin) in patients undergoing coronary stent implantation.' The Lancet, 1997.
The PURSUIT Trial Investigators. 'Inhibition of platelet glycoprotein IIb/IIIa with eptifibatide in patients with acute coronary syndromes.' The New England Journal of Medicine, 1998.
Scarborough, R.M., et al. 'Barbourin. A GPIIb-IIIa-specific integrin antagonist from the venom of Sistrurus m. barbouri.' The Journal of Biological Chemistry, 1991.
Tcheng, J.E., et al. 'Pharmacodynamics of chimeric glycoprotein IIb/IIIa integrin antiplatelet antibody Fab 7E3 in high-risk coronary angioplasty.' Circulation, 1994.
Gilchrist, I.C., et al. 'Pharmacodynamics and pharmacokinetics of higher-dose, double-bolus eptifibatide in percutaneous coronary intervention.' Circulation, 2001.
McClure, M.W., et al. 'Clinical significance of thrombocytopenia during a non-ST-elevation acute coronary syndrome. The platelet glycoprotein IIb/IIIa in unstable angina: receptor suppression using integrilin therapy (PURSUIT) trial experience.' Circulation, 1999.