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approvedImmune & Inflammation

Ecallantide

Also known as: Kalbitor, DX-88

Ecallantide (Kalbitor) is a 60-amino acid recombinant protein that acts as a potent and specific inhibitor of plasma kallikrein. FDA-approved in 2009 for the treatment of acute attacks of hereditary angioedema (HAE) in patients 12 years and older, it is the first kallikrein inhibitor approved for this indication. Produced in Pichia pastoris yeast, ecallantide blocks the kallikrein-kinin pathway that drives the excessive bradykinin production responsible for the debilitating swelling episodes characteristic of HAE.

3 cited references·4 researched benefits

Quick Answer

Ecallantide (Kalbitor) is a 60-amino acid kallikrein inhibitor FDA-approved for acute hereditary angioedema (HAE) attacks. It works by specifically blocking plasma kallikrein, the enzyme responsible for excessive bradykinin generation that causes severe tissue swelling. Administered as a 30 mg subcutaneous injection, ecallantide provides rapid symptom relief within 1-4 hours in clinical trials. It must be given by a healthcare professional due to a small risk of anaphylaxis.

Key Facts

Mechanism
Ecallantide is a Kunitz-type protease inhibitor engineered via phage display to bind plasma kallikrein with high affinity (Ki ~25 pM). By inhibiting kallikrein, it blocks the cleavage of high-molecular-weight kininogen (HMWK) to bradykinin, the vasoactive peptide responsible for increased vascular permeability and edema formation in HAE. Unlike C1-inhibitor replacement therapies that act upstream, ecallantide targets the specific protease (kallikrein) that is dysregulated when C1-inhibitor is deficient or dysfunctional. This mechanism also indirectly attenuates the contact activation (factor XII) pathway of coagulation.
Research Status
approved
Half-Life
~2 hours
Molecular Formula
C₂₈₇H₄₅₂N₇₈O₈₈S₇
Primary Use
Immune & Inflammation
Table of Contents

Benefits

  • Rapid resolution of acute HAE attacks — significant symptom improvement within 1-4 hours in EDEMA clinical trialsstrong
  • Effective for all HAE attack types including abdominal, facial, and peripheral swelling episodesstrong
  • Highly specific mechanism — selectively inhibits plasma kallikrein without broadly suppressing other serine proteasesstrong
  • Does not require IV access — subcutaneous administration allows treatment outside hospital ICU settingsmoderate

Dosage Protocols

RouteDosage RangeFrequencyNotes
Subcutaneous injection30 mg (three 10 mg injections)Per acute HAE attackAdministered as three separate 1 mL subcutaneous injections at different sites (abdomen, thigh, or upper arm). Must be administered by a healthcare professional. An additional 30 mg dose may be given within 24 hours if the attack persists.

Medical disclaimer

Dosage information is provided for educational reference only. Always follow your prescriber's instructions and consult a qualified healthcare provider before starting any peptide protocol.

Side Effects

  • Injection site reactions — erythema, swelling, pain, and pruritus at the subcutaneous injection site in 7-15% of patientscommon
  • Headache — reported in approximately 8-16% of patients in clinical trialscommon
  • Nausea and diarrhea — gastrointestinal symptoms in 5-13% of patientscommon
  • Anaphylaxis — reported in approximately 3-4% of patients; carries a black box warning requiring administration by a healthcare professionalserious
  • Upper respiratory tract infection symptoms — nasopharyngitis and fever in some patientsrare

Frequently Asked Questions

Why must ecallantide be given by a healthcare professional?
Ecallantide carries an FDA black box warning for anaphylaxis risk, occurring in approximately 3-4% of treated patients. Anaphylactic reactions have been observed as early as 8 minutes after injection. Because of this risk, ecallantide must be administered by a healthcare professional with appropriate medical support available to manage anaphylaxis, including injectable epinephrine. Patients cannot self-administer at home, unlike some other HAE therapies such as icatibant or C1-inhibitor concentrates.
How does ecallantide differ from icatibant for HAE treatment?
Both ecallantide and icatibant target the kallikrein-bradykinin pathway but at different points. Ecallantide inhibits plasma kallikrein, preventing bradykinin generation, while icatibant (Firazyr) blocks the bradykinin B2 receptor directly. Icatibant can be self-administered at home, whereas ecallantide requires healthcare professional administration due to anaphylaxis risk. Both show comparable efficacy for acute HAE attacks in clinical trials.
What is hereditary angioedema and why do standard treatments fail?
Hereditary angioedema (HAE) is a rare genetic disorder (affecting ~1 in 50,000 people) caused by deficiency or dysfunction of C1-inhibitor protein. This leads to uncontrolled activation of plasma kallikrein and excessive bradykinin production, causing recurrent episodes of severe subcutaneous and submucosal swelling. Standard antihistamines, corticosteroids, and epinephrine used for allergic angioedema are ineffective because HAE swelling is bradykinin-mediated, not histamine-mediated.

References

  1. 1
    Ecallantide for the treatment of acute attacks in hereditary angioedema (EDEMA4 trial)(2010)PubMed ↗
  2. 2
    A phase 3 trial of ecallantide in hereditary angioedema: the EDEMA3 study(2011)PubMed ↗
  3. 3
    Ecallantide: a plasma kallikrein inhibitor for the treatment of hereditary angioedema(2010)PubMed ↗

Latest Research

Last updated: 2026-02-19