What it is
Eptifibatide is a ring of seven building blocks: six amino acids and one capping residue. Its label spells them out — a mercaptopropionyl group, homoarginine (arginine with one extra carbon), glycine, aspartate, tryptophan, proline and a cysteinamide — with a disulfide bond tying the first to the last. It weighs 831.96.
It is made by chemical synthesis, not extracted from anything.
Where the idea came from
The design started in a snake. A 1999 review by its developer (Scarborough, PMID 10577440) states eptifibatide "was developed by mimicking the GP IIb/IIIa blocker barbourin, found in the venom of the southeastern pigmy rattlesnake." Barbourin belongs to the venom disintegrins — proteins that stop prey's blood clotting by jamming the platelet receptor. Structural work on barbourin (PMID 10815769) centres on its KGD loop; eptifibatide carries the same idea in a homoarginine-glycine-aspartate run inside a far smaller ring.
The same review describes the target profile: high specificity for the receptor, a short half-life, fast onset, and fast reversal once the drip stops.
How it works
Platelets clump by grabbing fibrinogen and von Willebrand factor through a surface receptor called glycoprotein IIb/IIIa. Eptifibatide occupies that receptor. The label describes the block as dose-dependent and reversible, which it attributes to the peptide letting go of the platelet.
| Measure (label) | Figure |
|---|---|
| Plasma half-life | About 2.5 hours |
| Bound to plasma protein | About 25% |
| Share cleared by the kidneys (healthy subjects) | About 50% |
| Kidney impairment (CrCl < 50 mL/min) | Clearance about halved; levels about doubled |
The trial record
| Trial | Patients | Setting | Result on the label |
|---|---|---|---|
| PURSUIT | 10,948 | Unstable angina or NSTEMI, 726 centres, 27 countries | Death or MI at 30 days 14.2% vs 15.7% placebo (p = 0.042); at 3 days 5.9% vs 7.6% |
| ESPRIT | 2,064 | Planned coronary stenting | Composite of death, MI, urgent revascularisation or bailout at 48 hours reduced |
| IMPACT II | — | Mostly balloon angioplasty | Listed among the three placebo-controlled studies |
Two details from PURSUIT: the gain came mainly from fewer non-fatal heart attacks (10.7% vs 12%), while deaths were close (3.5% vs 3.7%); and the lower-infusion arm was stopped early when both active arms bled at the same rate. All patients also received aspirin and, in most cases, heparin — eptifibatide was tested as an addition, not alone.
Safety
Bleeding is the label's most common complication, mostly at the arterial access site or from the gut or urinary tract. The label contraindicates it with recent bleeding, severe uncontrolled blood pressure, major surgery within six weeks, stroke within 30 days or any brain bleed, another IIb/IIIa blocker, and dialysis. It also lists a drop in platelet count, which calls for stopping both eptifibatide and heparin.
Where it stands
Drugs@FDA lists Integrilin (Merck, NDA 020718, 1998-05-18) as discontinued, and 14 generic applications, 8 with a current prescription presentation (openFDA, 2026-10-05). It is a hospital drug given by intravenous infusion; the dose is set by weight and kidney function within a cardiac procedure. PubMed indexes 1,360 records, 188 tagged as randomised controlled trials (2026-10-05).
Related reading
Eptifibatide is one of several approved drugs in this library that began as a natural molecule from another species — salmon calcitonin is another. For how a ring closed by a disulfide bond holds a short chain in shape, see lanreotide and octreotide; for the bond that joins every residue in the chain, see the peptide bond.