Page data last changed: . Registry refreshes and identity assessments are separate from scientific content review.
A protease-resistant decapeptide that blocks bradykinin-driven swelling.
Also known as: Firazyr
Part of the Foundational & therapeutic peptides cluster
Overview
Icatibant is a synthetic decapeptide peptidomimetic that selectively antagonizes the bradykinin B2 receptor. Because hereditary angioedema attacks are driven by excess bradykinin, blocking this receptor addresses the cause of the swelling, and it is an approved therapeutic for acute attacks. This page is educational only.
Source & context
Biological / chemical source: Synthetic decapeptide (peptidomimetic)
Primary research or clinical context: Approved for acute attacks of hereditary angioedema
Peptidomimetic stability
Icatibant contains five non-natural amino acids that make it resistant to peptidases, allowing subcutaneous self-administration during an attack. It exemplifies how incorporating unnatural residues converts a fragile peptide sequence into a durable receptor blocker.
Targeting the mediator
By competitively occupying the B2 receptor, icatibant prevents bradykinin from increasing vascular permeability. It is notably ineffective for ACE-inhibitor-induced angioedema, a distinction frequently used to teach the specificity of receptor-targeted peptides.
Sequence of the selected reference form
Sequence backbone for the reference form: Icatibant parent free peptide. Termini, stereochemistry and modifications are described below.
RRPXGXSXXR
R1 is D-Arg; X4 is L-(2S,4R)-Hyp; X6 is L-3-(2-thienyl)alanine; X8 is D-Tic; X9 is L-Oic with(2S,3aS,7aS) stereochemistry.. X marks a noncanonical residue; see the expanded sequence and reference chemistry below.
Analyze sequences in the playground →Structure & chemistry
Molecular identity & reference confidence
Source-supported reference
The selected full stereochemical parent agrees between the official label, PubChem and NIH GSRS. The old CID leaves five stereocentres undefined. The label also corrects the imported thienyl description to the 2-thienyl side chain.
- Molecular form
- Icatibant parent free peptide
- Species
- Synthetic bradykinin analogue; no natural source species applies
- Termini (N / C)
- Free D-arginyl amino terminus / Free L-arginine carboxylic acid
Average reference mass · Molecular identity assessment: 2026-10-05
Reference policy updated: 2026-10-05
- PubChem PUG REST selected parent properties · 2026-10-05
- PubChem selected-parent biologic notation · 2026-10-05
- PubChem selected-parent identifiers with depositor attribution · 2026-10-05
- NIH GSRS independently selected parent record · 2026-10-05
- Official product label chemical description, selected parent distinguished from formulation · 2026-10-05
H-D-Arg-Arg-Pro-Hyp-Gly-2Thi-Ser-D-Tic-Oic-Arg-OH
- Molecular formula
- C59H89N19O13S
- Average reference mass
- ≈ 1,304.5
- Backbone
- Icatibant parent free peptide
- C-terminus
- Free L-arginine carboxylic acid
- PubChem CID: 6918173
- CAS RN: 130308-48-4
- UNII: 7PG89G35Q7
Chemistry values: curated profile, PubChem.
Clinical development snapshot
ClinicalTrials.gov lists 33 registered studies with “Icatibant” as an intervention (snapshot 2026-09-06). A registry footprint is not evidence of efficacy or approval.
| NCT | Title | Phase | Status | Updated |
|---|---|---|---|---|
| NCT04113109 | Mechanisms Underlying Hypotensive Response to ARB/NEP Inhibition - Aim 2 | Phase 4 | completed | 2026-08-11 |
| NCT05509569 | A Survey of Icatibant in Pediatric Participants With Hereditary Angioedema | — | completed | 2026-08-07 |
| NCT05834777 | Prevention of Intradialytic Hypotension by Inhibiting Bradykinin B2 Receptor | Phase 3 | recruiting | 2026-04-15 |
| NCT04488081 | I-SPY COVID-19 TRIAL: An Adaptive Platform Trial for Critically Ill Patients | Phase 2 | active not recruiting | 2026-03-16 |
| NCT06346899 | A Study of Lanadelumab (Takhzyro) and Icatibant (Firazyr®) in Persons With HAE in China | — | completed | 2026-01-21 |
| NCT07009262 | A Study Observing US Patients With HAE Type I or II Who Take Icatibant to Treat HAE Attacks | — | completed | 2026-01-13 |
Icatibant — reconstitution calculator
Enter how much peptide is in the vial and how much diluent (e.g. bacteriostatic water) is added. The tool returns the resulting solution concentration — and, for any amount you type, the volume it corresponds to. This is educational arithmetic, not a dosing recommendation.
Reference form: Icatibant parent free peptideAverage reference mass: 1,304.5 Da
Enter an amount to see the volume it corresponds to.
Educational concentration mathematics only. This tool does not recommend a dose, amount, or protocol, and nothing here is medical advice. Many peptides are not authorized by Health Canada for human use — see our reconstitution and bacteriostatic-water guides for context.
FAQ about Icatibant
What is Icatibant?+
Icatibant is a synthetic decapeptide peptidomimetic that selectively antagonizes the bradykinin B2 receptor. Because hereditary angioedema attacks are driven by excess bradykinin, blocking this receptor addresses the cause of the swelling, and it is an approved therapeutic for acute attacks. This page is educational only.
What Canadian product status is recorded for Icatibant?+
Canadian product status for Icatibant has not been verified in this profile. No verified record here does not mean no authorization exists. Status depends on the product, formulation and use; consult Health Canada's product records.
What is the length of the selected reference form for Icatibant?+
The selected reference form (Icatibant parent free peptide) has 10 residues or residue-derived units in its backbone. Other forms in this family may have a different length.
Related peptides
References & further reading
- 1.Gras (2009). Icatibant for hereditary angioedema. Drugs Today (Barc)
- 2.Deeks (2010). Icatibant. Drugs
- 3.Mustonen et al. (2023). Icatibant in viral infections. Infect Dis (Lond)
- 4.Dubois et al. (2010). Icatibant. Br J Clin Pharmacol
- 5.Šimac et al. (2022). Is Icatibant Safe for the Treatment of Hereditary Angioedema During Pregnancy?. Curr Allergy Asthma Rep
- 6.Li et al. (2025). Icatibant Acts as a Balanced Ligand of MRGPRX2 in Human Skin Mast Cells. Biomolecules
- 7.Longhurst (2010). Management of acute attacks of hereditary angioedema: potential role of icatibant. Vasc Health Risk Manag
- 8.Medical Letter (2011). In brief: icatibant (Firazyr) for hereditary angioedema. Med Lett Drugs Ther
- 9.PubChem — compound summary for Icatibant (CID 6918173)
- 10.Wikipedia — Icatibant