Ecallantide
A kallikrein blocker for hereditary angioedema attacks
Ecallantide is a 60-amino-acid recombinant protein that blocks plasma kallikrein, the enzyme that releases bradykinin during hereditary angioedema attacks. Approved as Kalbitor in 2009, it is injected under the skin during an attack, but only by a healthcare professional because of a risk of anaphylaxis.
What is it?
Hereditary angioedema causes recurrent attacks of swelling of the skin, gut and airway, driven by bradykinin. Ecallantide blocks plasma kallikrein, the enzyme that releases bradykinin, and so treats an attack once it has started. At 60 amino acids it is a small protein rather than a peptide by FDA's definition, which is why it was licensed as a biologic. It is approved for people aged 12 and older.
In the EDEMA4 trial of 72 patients with moderate to severe attacks, the median treatment outcome score at four hours was 50 on ecallantide against 0 on placebo, with no treatment-related serious adverse events. The EDEMA3 trial found a similar four-hour benefit.
Its limitation is anaphylaxis. Across 230 patients and 1,045 doses, 3.5% had reactions meeting criteria for anaphylaxis, none on first exposure and all within an hour. The label carries a boxed warning and requires administration by a healthcare professional able to manage anaphylaxis. Its half-life is about two hours.
At a Glance
Every value in this table is printed from the Grey Peptides dataset, the same record the compound explorer and comparison tool read, so the three can never disagree.
Educational information, not medical advice. The doses on this page come from approved labels, published studies and, where no study exists, amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
Half-Life: How Much Remains
The dataset records a half-life of elimination half-life 2.0 ± 0.5 hours for Ecallantide. After each half-life, half of what was in the circulation is gone, so about 3% remains after five. Real clearance varies with the person, the dose, the route and kidney or liver function; this is arithmetic on a published figure, not a dosing tool.
Published Research
The trials and safety data behind ecallantide, from their PubMed abstracts.
EDEMA4: phase 3
In 72 patients with acute attacks, the median treatment outcome score at 4 hours was 50.0 on ecallantide against 0.0 on placebo (P = 0.004), with symptom severity improving more; there were no deaths, treatment-related serious adverse events or withdrawals for adverse events.
EDEMA3 and the evidence base
A review describing ecallantide as a selective, reversible plasma kallikrein inhibitor and summarising EDEMA3, in which a single 30 mg dose produced a significantly greater symptom response at 4 hours than placebo.
Anaphylaxis after ecallantide
Among 230 patients given 1,045 doses, 8 (3.5%) had reactions meeting anaphylaxis criteria, none on first exposure, all within 1 hour, and all resolved with standard treatment.
Role in managing attacks
A review of hereditary angioedema treatment placing ecallantide among on-demand therapies for acute attacks, alongside long-term and short-term prophylaxis.
Side Effects & Contraindications
Reported Side Effects
From the studies above.
Contraindications & Cautions
Warnings from the Kalbitor label (DailyMed, effective July 1, 2025).
Legal Status
Ecallantide is an approved prescription biologic in the US.
Frequently Asked Questions
?Is ecallantide a peptide?
It is a 60-amino-acid protein. FDA treats chains longer than 40 amino acids as proteins, which is why ecallantide was licensed as a biologic.
?Why must a healthcare professional give it?
Because of anaphylaxis: about 3.5% of patients had anaphylactic reactions in pooled data, and the label requires administration where anaphylaxis can be treated.
?What does ecallantide treat?
Acute attacks of hereditary angioedema in people 12 and older, by blocking the enzyme that releases bradykinin.
?How is ecallantide given?
The label dose is 30 mg as three 10 mg injections under the skin during an attack; if the attack persists, another 30 mg may be given within 24 hours, always by a healthcare professional.
?How quickly does ecallantide work?
In the EDEMA4 trial, the estimated time to significant improvement was 165 minutes on ecallantide against more than 240 minutes on placebo, a difference that was not statistically significant; the main four-hour symptom score did improve significantly.
References
- [fda] US FDA, Drugs@FDA (openFDA): KALBITOR, BLA 125277 (December 1, 2009). Read October 3, 2026.
- [fda-pi] FDA. Kalbitor (ecallantide) US prescribing information (DailyMed set f56aec67-c662-477c-b866-bfc23e8809cf, effective July 1, 2025). Read October 3, 2026.
- [clinical-trial] Cicardi M, et al. "Ecallantide for the treatment of acute attacks in hereditary angioedema." N Engl J Med, 2010;363(6):523-31. PMID: 20818887.
- [pubmed] Garnock-Jones KP. "Ecallantide: in acute hereditary angioedema." Drugs, 2010;70(11):1423-31. PMID: 20614949.
- [pubmed] Craig TJ, et al. "Characterization of anaphylaxis after ecallantide treatment of hereditary angioedema attacks." J Allergy Clin Immunol Pract, 2015;3(2):206-212.e4. PMID: 25609335.
- [pubmed] Duffey H, et al. "Management of acute attacks of hereditary angioedema: role of ecallantide." J Blood Med, 2015;6:115-23. PMID: 25931832.
Sources & Citations
Studies were read from their PubMed records; regulatory sources are listed below, read October 3, 2026.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Consult a licensed healthcare provider before making health decisions.