Summary

Eptifibatide (Integrilin) is a synthetic cyclic heptapeptide derived from the structure of barbourin, a disintegrin found in pygmy rattlesnake venom. It functions as a reversible antagonist of the platelet glycoprotein IIb/IIIa (GPIIb/IIIa) receptor, preventing platelet aggregation. Licensed by the MHRA, EMA, and FDA as an adjunct to percutaneous coronary intervention (PCI) and for acute coronary syndromes (unstable angina and NSTEMI), eptifibatide is supported by large Phase 3 RCTs including PURSUIT (n=10,948) and ESPRIT. Though its routine use has declined in the era of oral P2Y12 inhibitors, it remains an important reference compound in platelet pharmacology and a notable example of venom-derived peptide drug design.

Overview

Eptifibatide is a synthetic cyclic heptapeptide that functions as a reversible antagonist of the glycoprotein IIb/IIIa (GPIIb/IIIa) receptor on platelets. Marketed under the brand name Integrilin, it is a licensed medicine approved by the MHRA, EMA, and FDA as an adjunct to percutaneous coronary intervention (PCI) and for the management of acute coronary syndromes (ACS), including unstable angina and non-ST-elevation myocardial infarction (NSTEMI).

Eptifibatide was developed based on the structure of barbourin, a disintegrin peptide found in the venom of the southeastern pygmy rattlesnake (Sistrurus miliarius barbouri). The disintegrin contains a Lys-Gly-Asp (KGD) sequence that confers high specificity for the GPIIb/IIIa receptor. Eptifibatide incorporates this KGD motif within a cyclic heptapeptide structure, providing receptor specificity and a manageable pharmacokinetic profile.

While eptifibatide is not a substance encountered in the non-medical research peptide community, it represents an important example of venom-derived peptide drug design and is a key reference compound in platelet pharmacology research. Its use has declined in recent years with the advent of newer oral P2Y12 inhibitors, but it retains a role in high-risk PCI procedures.

Research Summary

PURSUIT Trial — Unstable Angina / NSTEMI

The pivotal evidence for eptifibatide in non-ST-elevation ACS comes from the PURSUIT trial (PRISM-PLUS Investigators, NEJM, 1998). This was a large randomised, double-blind, placebo-controlled trial enrolling 10,948 patients with unstable angina or NSTEMI.

Patients received eptifibatide (180 µg/kg bolus followed by 2.0 µg/kg/min infusion for 72–96 hours) or placebo, in addition to standard care including aspirin and heparin. The primary endpoint — death or non-fatal MI at 30 days — occurred in 14.2% of the eptifibatide group versus 15.7% of placebo (p=0.042). The benefit was most pronounced in patients undergoing early PCI.

IMPACT-II Trial — PCI

The IMPACT-II trial (NEJM, 1997) enrolled 4,010 patients undergoing PCI and tested two eptifibatide regimens (135 µg/kg bolus + 0.5 µg/kg/min infusion, or 135 µg/kg bolus + 0.75 µg/kg/min infusion) versus placebo. The trial demonstrated a trend toward reduced composite endpoints (death, MI, urgent revascularisation) at 30 days, though the effect was modest and did not reach statistical significance for the lower-dose arm.

ESPRIT Trial — High-Risk PCI

The ESPRIT trial (O'Shea et al., JAMA, 2001) used a higher double-bolus regimen (180 µg/kg bolus ×2, 10 minutes apart, followed by 2.0 µg/kg/min infusion) in 2,064 patients undergoing coronary stenting. The trial was stopped early due to efficacy — the composite endpoint of death, MI, urgent target vessel revascularisation, or thrombotic bailout at 48 hours was reduced from 10.5% (placebo) to 6.6% (eptifibatide) (p=0.0015).

Declining Use

Several meta-analyses and more recent trials (EARLY-ACS, 2009) have questioned the incremental benefit of GPIIb/IIIa inhibitors in the era of dual antiplatelet therapy (DAPT) with prasugrel and ticagrelor. Current ESC and NICE guidelines recommend eptifibatide primarily for bailout use during high-risk PCI rather than routine upstream use.

Evidence grade: Strong — supported by multiple large Phase 3/4 RCTs and meta-analyses, though contemporary use has narrowed.

Commonly Discussed Protocols

All protocols below are documented from clinical trial literature and prescribing information for research reference only. Eptifibatide is a licensed POM in the UK and must only be administered under medical supervision in a hospital setting.

ACS (Unstable Angina / NSTEMI)

  • Bolus: 180 µg/kg intravenous bolus
  • Infusion: 2.0 µg/kg/min continuous IV infusion
  • Duration: Up to 72 hours (or 96 hours if PCI performed)
  • Renal adjustment: Infusion reduced to 1.0 µg/kg/min if creatinine clearance <50 mL/min

PCI (ESPRIT Double-Bolus Regimen)

  • Bolus 1: 180 µg/kg IV
  • Bolus 2: 180 µg/kg IV, 10 minutes after first bolus
  • Infusion: 2.0 µg/kg/min continuous IV infusion for 18–24 hours post-PCI
  • Renal adjustment: Infusion reduced to 1.0 µg/kg/min if CrCl <50 mL/min

Discontinuation Before Surgery

  • Pre-operative: Stop infusion at least 2–4 hours before major surgery (CABG) due to reversible platelet inhibition
  • Note: This reversibility is a key advantage over irreversible antiplatelet agents

Stacking

In clinical practice, eptifibatide is used in combination with:

  • Aspirin: Standard concurrent therapy
  • Heparin (unfractionated): Standard concurrent anticoagulation
  • P2Y12 inhibitors (clopidogrel, prasugrel, ticagrelor): Used in 'triple therapy' — increases bleeding risk significantly

Eptifibatide is NOT combined with other GPIIb/IIIa inhibitors (abciximab, tirofiban). There is no established research literature on combining eptifibatide with non-cardiovascular peptides.

Storage & Reconstitution

  • Formulation: Supplied as a sterile solution in 10 mg/mL or 2 mg/mL vials (pre-mixed, no reconstitution needed)
  • Storage: Store at 2–8°C (refrigerated). Do not freeze. Protect from light.
  • Administration: Ready-to-use solution; may be diluted in 0.9% sodium chloride for infusion. Do not shake.
  • Shelf life: 24 months from manufacture when stored at 2–8°C.
  • Note: May be stored at room temperature (25°C) for up to 2 months if used before expiry date.

Blood Work

In clinical practice, the following are monitored during eptifibatide therapy:

  • Activated clotting time (ACT) or aPTT: Monitored to guide concurrent heparin dosing; eptifibatide itself does not significantly prolong aPTT.
  • Platelet count: Baseline and at 4 hours post-initiation — monitor for acute profound thrombocytopenia (rare but serious adverse effect, incidence <1%)
  • Haemoglobin / haematocrit: Monitor for bleeding — major bleeding occurs in approximately 10–13% of patients in therapeutic dose ranges
  • Creatinine / renal function: Eptifibatide is renally cleared; dose adjustment required for CrCl <50 mL/min
  • Activated partial thromboplastin time (aPTT): For heparin titration

UK Legal Status

Eptifibatide is a Prescription-Only Medicine (POM) in the UK, licensed by the MHRA for:

  • Prevention of early myocardial infarction in patients with unstable angina or NSTEMI
  • Adjunctive therapy in patients undergoing PCI

Supplied as Integrilin. It is restricted to hospital use and administered only by specialists in cardiology/critical care. It is available on the NHS for its licensed indications subject to local formulary approval. Unlicensed supply for human use is illegal. Purchase by research institutions for in vitro or animal studies is legal under research chemical exemptions, but suppliers must not market it for human consumption.

References

References

  1. PRISM-PLUS Study Investigators. Inhibition of the platelet glycoprotein IIb/IIIa receptor with tirofiban in unstable angina and non-Q-wave myocardial infarction (PURSUIT). N Engl J Med. 1998;339(7):436-43. doi:10.1056/NEJM199808133390704
  2. IMPACT-II Investigators. Randomised placebo-controlled trial of eptifibatide on complications in patients undergoing coronary angioplasty. Lancet. 1997;349(9063):1422-8. doi:10.1016/S0140-6736(97)01024-3
  3. O'Shea JC, Buller CE, Cantor WJ, et al. ESPRIT: Long-term efficacy of eptifibatide in PCI. JAMA. 2002;287(5):618-21. doi:10.1001/jama.287.5.618
  4. Scarborough RM, Naughton MA, Teng W, et al. Design of potent and specific integrin antagonists: Potent and selective inhibition of GPIIb-IIIa. J Biol Chem. 1993;268(2):1066-73.
  5. Giugliano RP, White JA, Bode C, et al. EARLY-ACS: Early versus delayed eptifibatide in acute coronary syndrome. N Engl J Med. 2009;360(21):2176-90. doi:10.1056/NEJMoa0900110
  6. Integrilin (eptifibatide) Summary of Product Characteristics. Schering-Plough Ltd. MHRA. Accessed 2025.