Source: FDA label
| Molecular formula | C305H442N88O91S8 |
|---|---|
| Molecular weight | 7054 g/mol |
| Registered trials | 13 |
| PubChem CID | 44152182 |
| Drug class | Plasma Kallikrein Inhibitor [EPC] |
| Brand names | Kalbitor |
Boxed warning: The FDA label for this compound includes a boxed warning, the FDA's strongest safety warning. See the full prescribing information for details.
Mechanism of Action
12.1 Mechanism of Action Hereditary angioedema (HAE) is a rare genetic disorder caused by mutations to C1-esterase-inhibitor (C1-INH) located on Chromosome 11q and inherited as an autosomal dominant trait. HAE is characterized by low levels of C1-INH activity and low levels of C4. C1-INH functions to regulate the activation of the complement and intrinsic coagulation (contact system pathway) and is a major endogenous inhibitor of plasma kallikrein. The kallikrein-kinin system is a complex proteo
Hereditary angioedema attacks can cause sudden, painful swelling, and people living with the condition often want treatment options that act specifically on the underlying process. Ecallantide, sold as Kalbitor, is one such option built to interrupt a specific protein pathway involved in these attacks.
Key takeaways
- Ecallantide (Kalbitor) is approved to treat acute attacks of hereditary angioedema in patients 12 and older.
- It works by inhibiting plasma kallikrein, a protein central to HAE attacks.
- The label carries a boxed warning.
- At least 13 registered trials have studied ecallantide, including a completed Phase 3 efficacy and safety study.
- FDA Adverse Event Reporting System data show hereditary angioedema itself as the most-reported term, alongside headache and malaise.
What Ecallantide Is
Ecallantide is classified as a plasma kallikrein inhibitor. Hereditary angioedema is a rare genetic disorder caused by mutations affecting C1-esterase-inhibitor, a protein that normally regulates the kallikrein-kinin system. Low C1-esterase-inhibitor activity allows plasma kallikrein to drive the swelling seen in HAE attacks, and ecallantide works by blocking this protein directly.
What Ecallantide Is Approved For
Kalbitor is indicated for treatment of acute attacks of hereditary angioedema in patients 12 years of age and older. It is not described as a preventive therapy, but rather as treatment for attacks as they occur. The label carries a boxed warning, which prescribers and patients should be aware of.
What the Evidence Shows
At least 13 trials have registered ecallantide as a study drug. Among these, a completed Phase 3 trial evaluated the efficacy and safety of the compound (then known as DX-88) specifically for treating acute HAE attacks. A separate completed observational study examined real-world safety of Kalbitor in the same patient population, and a completed Phase 2 trial explored its use for reducing surgical blood loss.
Reported Side Effects
FAERS data reflect reports submitted to a passive surveillance system, which means these are counts of reported reactions, not confirmed incidence or proven causation. The most frequently reported term is hereditary angioedema itself (782 reports), which likely reflects reports describing the underlying condition or breakthrough attacks rather than a drug-caused effect. Beyond this, reports include general symptoms such as malaise (86), headache (84), and pain (70), along with hypersensitivity (68). Other reports describe off-label use (170), perceived drug ineffectiveness (147), and dose omission issues (72), reflecting real-world usage patterns rather than a single safety signal.
FAQ
What is ecallantide used for?
Ecallantide, marketed as Kalbitor, is approved to treat acute attacks of hereditary angioedema in patients 12 years of age and older. It is used to manage attacks as they happen rather than to prevent them. It works by inhibiting plasma kallikrein, a protein that drives the swelling seen in these attacks.
How does ecallantide work?
Ecallantide is a plasma kallikrein inhibitor. In hereditary angioedema, low activity of C1-esterase-inhibitor allows plasma kallikrein to become overactive, contributing to swelling attacks. By blocking plasma kallikrein directly, ecallantide targets this underlying mechanism.
Does ecallantide have a boxed warning?
Yes, the FDA label for Kalbitor includes a boxed warning. Patients and prescribers should review the full label for details on this warning before use.
What side effects have been reported with ecallantide?
Reports submitted to the FDA Adverse Event Reporting System include hereditary angioedema, headache, malaise, and pain, among others. These are counts of reported reactions, not confirmed incidence or proof that the drug caused the event. Reports of off-label use and perceived ineffectiveness also appear in the data.
How much clinical evidence exists for ecallantide?
At least 13 trials have been registered studying ecallantide. These include a completed Phase 3 trial on treating acute hereditary angioedema attacks and a completed observational safety study of Kalbitor in the same patient population.
This page is an editorial information resource. It does not sell, prescribe, or recommend any medication.
Content is editorial information, not medical advice. Talk to your doctor before any treatment decision.
Sources: FDA label (DailyMed) ClinicalTrials.gov FDA Adverse Event Reporting System (FAERS) PubChem
Updated 2026-11-07