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Endocrine · Reference monograph

Plasma kallikrein inhibitor for hereditary angioedema attacks

Reference compound — not available from Purity Peptides. Shown for research context.

Overview

Ecallantide is a 60-amino-acid recombinant protein that potently and selectively inhibits plasma kallikrein. It is based on a Kunitz domain from human tissue factor pathway inhibitor, re-engineered by Dyax using phage-display technology to bind plasma kallikrein with very high affinity. It is produced in the yeast Pichia pastoris and, at roughly 7 kDa, sits at the boundary between large peptides and small proteins.

Ecallantide was approved by the FDA in 2009 as Kalbitor for acute attacks of hereditary angioedema, a rare disorder usually caused by deficiency or dysfunction of C1 esterase inhibitor. Its EU marketing application was withdrawn. Scientifically, ecallantide is significant for two reasons. First, it helped confirm the central role of plasma kallikrein and bradykinin in angioedema, an insight that later guided long-acting kallikrein inhibitors. Second, it is a widely cited success of phage display as a protein engineering method, a field recognised by the 2018 Nobel Prize in Chemistry. Hypersensitivity reactions, including anaphylaxis, are its best-documented safety concern.

Mechanism studied

  1. Ecallantide
  2. Plasma kallikrein inhibition
  3. Bradykinin ↓
  4. Oedema endpoints

Ecallantide is a reversible, high-affinity inhibitor of plasma kallikrein, a serine protease of the contact activation system. Plasma kallikrein cleaves high-molecular-weight kininogen to release bradykinin, a nonapeptide that binds endothelial B2 receptors and increases vascular permeability. In hereditary angioedema, insufficient C1 esterase inhibitor activity leaves kallikrein poorly controlled, so bradykinin accumulates and fluid leaks into tissues. By occupying the kallikrein active site, ecallantide blocks bradykinin generation upstream of its receptor. This places it mechanistically between C1 inhibitor replacement and the B2 receptor antagonist icatibant, which acts downstream at the receptor itself.

Research highlights

  • 01Engineered from a human Kunitz domain using phage display, a method later recognised by the 2018 Nobel Prize in Chemistry.
  • 02Approved in the US in 2009 as one of the first agents targeting plasma kallikrein directly.
  • 03Clinical studies helped establish bradykinin, not histamine, as the key mediator of hereditary angioedema attacks.
  • 04Hypersensitivity and anaphylaxis observations shaped research into immunogenicity of engineered proteins.
  • 05Its success informed development of later long-acting kallikrein inhibitors, including antibody and small-molecule approaches.

Latest published research

190 papers on PubMed →

  1. Diverse Trial Designs, Populations, and Outcomes: A Systematic Literature Review of Trials for the Treatment of Hereditary Angioedema Attacks

    Tachdjian R et al. · Advances in therapy · 2026 Sep · PMID 42313271

  2. Sebetralstat (Ekterly) for treatment of hereditary angioedema attacks

    The Medical letter on drugs and therapeutics · 2026 Feb 16 · PMID 41649362

  3. Performance evaluation of the QIAstat-Dx gastrointestinal panel 2 for the detection of Clostridioides difficile against multiple commercial assays

    Sabharwal L et al. · Journal of clinical microbiology · 2025 Nov 12 · PMID 41117599

  4. Barely There But Existent: Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema

    Butt MA et al. · Cureus · 2025 Oct · PMID 41209890

  5. Ecallantide

    · 2006 · PMID 33497163

  6. Targeting the contact-kinin system: A cyclopeptide with anti-thromboinflammatory properties against stroke

    Wang W et al. · European journal of pharmacology · 2025 Jul 5 · PMID 40058753

  7. Indirect treatment comparison of oral sebetralstat and intravenous recombinant human C1 esterase inhibitor for on-demand treatment of hereditary angioedema attacks

    Li HH et al. · Allergy, asthma, and clinical immunology : official journal of the Canadian Society of Allergy and Clinical Immunology · 2025 Mar 15 · PMID 40089800

  8. Interplay between on-demand treatment trials for hereditary angioedema and treatment guidelines

    Cohn DM et al. · The Journal of allergy and clinical immunology · 2025 Mar · PMID 39724968

Live feed from PubMed (NCBI) for “Ecallantide”, updated 2026-10-30. Listing a paper is not an endorsement of its findings.

Registered studies

13 on ClinicalTrials.gov →

From the public ClinicalTrials.gov registry for “Ecallantide”, updated 2026-10-30. Shown for research context only; Purity Peptides products are not for human use.

Key references

  1. [1]Manufacturer's prescribing information — FDA / EMA / ANVISA
  2. [2]Cicardi et al., 2010 — N Engl J Med 363:523–531

FAQ

  • Ecallantide is a 60-residue recombinant polypeptide of about 7 kDa built on a Kunitz domain scaffold. It is often described as a small protein, sitting at the boundary between large peptides and conventional protein therapeutics.

  • Dyax used phage display to screen large libraries of variants of a human Kunitz domain, selecting those that bound plasma kallikrein most tightly. Ecallantide emerged from this directed-evolution approach.

  • Ecallantide blocks plasma kallikrein, preventing bradykinin from being generated. Icatibant blocks the bradykinin B2 receptor, preventing bradykinin that has already formed from acting. Both are studied as tools in kallikrein-kinin research.

FOR RESEARCH USE ONLY.Not for human or veterinary use. Not intended to diagnose, treat, cure, or prevent any disease.

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