Peptide education
Icatibant
Firazyr · Icatibant acetate
Icatibant is a prescription medicine for treating an acute attack of hereditary angioedema (HAE) in adults. It blocks a receptor for bradykinin, a signal involved in the swelling and pain of HAE. Firazyr is the approved subcutaneous injection.
In FAST-3, people with skin or abdominal attacks reached a 50% reduction in the trial's symptom score in a median of 2.0 hours with icatibant and 19.8 hours with placebo. That is an improvement threshold, not the time to complete recovery.
Overview
Quick answer
Treating an attack is different from preventing one. The U.S. label covers acute HAE attacks in adults; it does not establish a general treatment for every kind of swelling. Throat or airway symptoms still need immediate medical attention.
What does icatibant do?
It competes with bradykinin at the B2 receptor. In HAE related to C1 inhibitor deficiency or dysfunction, excess bradykinin is implicated in attacks of swelling and pain.
Is it used every day to prevent attacks?
The Firazyr label describes treatment of an acute attack, not a preventive schedule. The decision about a person's broader HAE care is separate.
What amount appears in the U.S. label?
The label describes 30 mg by subcutaneous injection into the abdomen. For inadequate response or recurring symptoms, it permits additional doses at least 6 hours apart, with no more than 3 doses in 24 hours. Patients may self-administer after training by a healthcare professional. This is label context, not a personal treatment plan.
Does it make throat swelling safe to manage at home?
No. The label says someone with laryngeal symptoms should seek immediate medical attention in an appropriate healthcare facility in addition to taking Firazyr.
Does it work for swelling caused by an ACE inhibitor?
That is a different clinical question and is outside the Firazyr indication. Trials have disagreed: a small comparison with steroid and antihistamine treatment favored icatibant, while a larger placebo-controlled trial found no difference in time to meeting discharge criteria.
Evidence
Evidence snapshot
The label specifies adults aged 18 or older and treatment of attacks.
Median time to at least 50% reduction in the composite symptom score for skin or abdominal attacks, with icatibant versus placebo.
FAST-1 found no significant difference from placebo on its primary endpoint; FAST-2 favored icatibant against tranexamic acid.
A small active-comparator study was positive, but a larger placebo-controlled study found no benefit on its discharge-criteria endpoint.
Injection-site reactions occurred in 97% of icatibant-treated patients in the two placebo-controlled studies summarized in the label.
Claims
Common claims vs evidence
| Claim | Human evidence | Mechanistic evidence | Verdict |
|---|---|---|---|
| Icatibant can shorten symptoms during an HAE attack. | FAST-3 found a shorter median time to at least 50% improvement in a composite symptom score for skin and abdominal attacks. The earlier FAST trials had different results on their primary endpoints. | Icatibant blocks the bradykinin B2 receptor, a target relevant to HAE attacks. | Supported for acute HAE attacks in the adult prescription-drug context, with results depending on the outcome and population measured. |
| An injection means airway swelling no longer needs emergency care. | FAST-3 included only a small number of laryngeal attacks. The label warns that airway obstruction can occur and calls for immediate medical attention. | False. Treatment and immediate medical assessment are both important. | |
| Blocking bradykinin proves icatibant works for ACE inhibitor swelling. | The small active-comparator trial and a larger placebo-controlled trial reached different conclusions. In the latter, median time to discharge criteria was 4.0 hours in each group. | A plausible receptor target does not settle whether a treatment improves an outcome in a different cause of angioedema. | Not established by these studies. ACE inhibitor-associated swelling is not the labeled indication. |
Bottom line
Main takeaway
Firazyr is for acute HAE attacks in adults. Throat swelling remains urgent even when the prescribed medicine has been used.
The headline FAST-3 result measures time to a 50% symptom-score reduction, not complete resolution. The labeled repeat-dose limits are a separate detail.
Read FAST-3 alongside FAST-1 and FAST-2, then keep the ACE inhibitor studies separate by population, comparator, and endpoint.
Identity
What it is
Icatibant is a synthetic peptide containing ten amino-acid residues. The approved Firazyr product is a single-dose prefilled syringe for subcutaneous injection.
Hereditary angioedema can cause recurrent swelling in the skin, abdomen, or airway. The label connects the common C1 inhibitor-deficient forms with excess bradykinin signaling; icatibant acts at the B2 receptor.
Use context
Routes, doses, and cycle patterns
The doses in the U.S. label and clinical studies apply to specific products, populations, and routes. They are not an individual treatment plan.
Human studies and product labels
Firazyr U.S. label
- Purpose
- Treatment of an acute HAE attack in an adult
- Context
- Label-reported, prescription product
- Route
- Subcutaneous injection in the abdominal area
- Amount
- 30 mg per dose
- Frequency
- Additional doses at least 6 hours apart if response is inadequate or symptoms recur
- Duration
- No more than 3 doses in any 24-hour period
The label allows patient self-administration after professional training. It directs people with laryngeal symptoms to seek immediate medical attention in addition to treatment.
FAST-3 blinded comparison
- Purpose
- Acute HAE attack symptoms
- Context
- Study-reported randomized comparison, not a recommendation
- Route
- Subcutaneous injection
- Amount
- One 30 mg injection compared with placebo
- Frequency
- Once in the blinded comparison
- Duration
- Acute attack follow-up
The primary non-laryngeal analysis included 43 people assigned to icatibant and 45 assigned to placebo. The primary outcome was time to at least a 50% reduction in symptom severity.
ACE inhibitor-associated upper-airway swelling trial
- Purpose
- Time to meeting discharge criteria
- Context
- Study-reported, outside the HAE label
- Route
- Subcutaneous injection
- Amount
- 30 mg compared with placebo
- Frequency
- Once in the randomized study
- Duration
- Acute episode
This 121-person randomized trial found no difference in its primary endpoint. A separate smaller study using a different comparator had a positive result.
What varies
- Indication: acute HAE attacks are not the same as all other causes of swelling.
- Airway: laryngeal symptoms require immediate medical attention after treatment.
- Route and product: the label concerns a specified subcutaneous prescription injection.
- Endpoint: 50% symptom improvement is not complete resolution.
Research
Research evidence
Controlled human studies support a narrow acute HAE indication. FAST-1 and FAST-2 used the same primary endpoint but had different comparators and results; FAST-3 used a different symptom-score endpoint. Studies in ACE inhibitor-associated swelling produced conflicting results and cannot be treated as proof for that use.
| Study / evidence area | Population | Design | Product context | Main outcome | Limitations | Weight |
|---|---|---|---|---|---|---|
| FAST-3 | People with C1 inhibitor-deficient or dysfunctional HAE | Randomized, double-blind, placebo-controlled phase 3 study | 30 mg subcutaneous icatibant versus placebo | For skin or abdominal attacks, median time to at least 50% symptom reduction was 2.0 hours with icatibant versus 19.8 hours with placebo. | The main comparison was non-laryngeal. The small laryngeal sample does not remove the need for urgent airway care. | Strong |
| FAST-1 and FAST-2 | People with HAE and skin or abdominal attacks | Two randomized controlled trials with different comparators | Icatibant versus placebo or tranexamic acid | Both trials measured time to clinically significant relief of the main symptom. FAST-1 found no significant difference from placebo; FAST-2 favored icatibant against tranexamic acid. | The comparators differed and both trials had relatively small groups. | Strong |
| ACE inhibitor-associated upper-airway angioedema | Adults with ACE inhibitor-associated swelling | Two separate randomized trials with different comparators | Subcutaneous icatibant outside the HAE indication | A small active-comparator study favored icatibant. A later placebo-controlled study found no difference in time to discharge criteria. | Populations, comparators, and endpoints differ. Neither study changes the approved HAE indication. | Mixed |
Use context
Reported use context
The Firazyr label describes treatment of acute HAE attacks in adults. FAST-3 tested a single 30 mg subcutaneous dose for an acute attack.
Study and label context
One 30 mg injection was compared with placebo for an acute attack.
Study-reported only, not a recommendation.Cautions
Safety and unknowns
- Airway obstruction is a risk with laryngeal HAE attacks. The label calls for immediate medical attention in addition to Firazyr treatment.
- Injection-site reactions occurred in 97% of treated participants in the label's placebo-controlled trials. Fever, increased liver enzymes, dizziness, and rash are also listed among common adverse reactions.
- Firazyr may reduce the blood-pressure-lowering effect of ACE inhibitors; the label notes that the HAE trials excluded people taking those medicines.
- The U.S. label says safety and effectiveness have not been established in patients under 18. Pregnancy and lactation evidence is limited.
Product quality
Product identity and quality
Firazyr is a sterile, single-dose, prefilled syringe with a defined drug concentration. The clinical evidence concerns that regulated product context.
A similar name on another preparation does not establish matching identity, concentration, or sterility.
Product and route
The label and FAST-3 studied a subcutaneous prescription injection, not an arbitrary formulation.
Training and urgent care
The label describes professional training for self-administration and immediate medical attention for laryngeal symptoms.
Mechanism
How it is proposed to work
Icatibant blocks the B2 receptor that responds to bradykinin. In HAE, that signaling is associated with the swelling and pain of an attack.
The drug is a competitive, selective B2 receptor antagonist. It acts at the receptor rather than replacing deficient C1 inhibitor.
Mechanism alone does not determine the result in other forms of angioedema; the ACE inhibitor trials used different comparators and produced conflicting results.
FAQ
Common questions
Does icatibant prevent hereditary angioedema attacks?
The Firazyr label describes treatment of acute attacks in adults, not prevention.
Does an injection replace emergency care for throat swelling?
No. The label says people with laryngeal symptoms should seek immediate medical attention as well as receiving treatment.
Details
Technical details
Sources
References
- 1.
DailyMed. Firazyr prescribing information
- 2.
PubMed. FAST-3 randomized trial in hereditary angioedema
doi:10.1016/j.anai.2011.08.015 PMID:22123383 NCT00912093
- 3.
ClinicalTrials.gov. FAST-3 study results
NCT00912093
- 4.
PubMed. FAST-1 and FAST-2 randomized trials in hereditary angioedema
PMID:20818888
- 5.
PubMed. Randomized trial in ACE inhibitor-induced angioedema
doi:10.1056/NEJMoa1312524 PMID:25629740
- 6.
PubMed. Placebo-controlled trial in ACE inhibitor-induced upper-airway angioedema
doi:10.1016/j.jaip.2017.03.003 PMID:28552382