Is icatibant FDA-approved, and what does the research show?

What is icatibant?

Icatibant is a man-made peptide of ten amino acids, which its label calls a synthetic decapeptide ¹. Five of the ten are amino acids the body does not use to build its own proteins ¹. It is sold in the United States by Takeda as Firazyr ¹.

It belongs to one drug class, bradykinin B2 receptor antagonists ¹. Bradykinin is a substance the body produces that widens blood vessels ¹. The label calls it "a vasodilator which is thought to be responsible for the characteristic HAE symptoms of localized swelling, inflammation, and pain" ¹. The B2 receptor is the docking site on cells where bradykinin acts, and an antagonist is a molecule that sits in that site and blocks it ¹. Icatibant is not a peptide people take for weight, muscle, skin or energy.

Is icatibant FDA-approved?

Yes. Icatibant is approved by FDA as the prescription medicine Firazyr, with initial U.S. approval in 2011 ¹. FDA's Drugs@FDA record shows the new drug application, NDA 022150, approved on August 25, 2011, with marketing status "Prescription," and names Takeda Pharms USA as its sponsor ². The approval letter approved it "for the treatment of acute attacks of hereditary angioedema in adults 18 years of age and older" ⁵. Drugs@FDA also lists eight generic icatibant acetate applications with marketing status "Prescription" as of November 9, 2026, the date of its data ².

The label has one indication: "FIRAZYR (icatibant) is indicated for the treatment of acute attacks of hereditary angioedema (HAE) in adults 18 years of age and older" ¹. Hereditary angioedema is an inherited disorder marked by "recurrent attacks of angioedema of the skin, larynx, and gastrointestinal tract" ⁴. That is sudden swelling of the skin, the larynx (voice box) or the gut ⁴. The label says it "is caused by an absence or dysfunction of C1-esterase-inhibitor," a protein that normally keeps in check the chain of enzymes that produces bradykinin ¹.

What the status means for a reader is a prescription from a clinician, and a medicine used only when an attack is under way ¹. The label says patients "may self-administer FIRAZYR upon recognition of symptoms of an HAE attack after training under the guidance of a healthcare professional" ¹. It lists no use for weight, for wellness or for any condition other than hereditary angioedema ¹. It says that "safety and effectiveness in pediatric patients below the age of 18 years have not been established" ¹. The label was last revised in June 2025 ¹.

See the FDA status of every peptide, updated weekly.

How does icatibant work?

The label describes icatibant as "a competitive antagonist selective for the bradykinin B2 receptor, with an affinity similar to bradykinin" ¹. In plain words, it competes with bradykinin for the same receptor and binds it about as strongly, so bradykinin cannot deliver its signal ¹. The label states the result in one sentence: "Icatibant inhibits bradykinin from binding the B2 receptor and thereby treats the clinical symptoms of an acute, episodic attack of HAE" ¹.

In healthy young subjects given bradykinin as a challenge, intravenous icatibant inhibited the fall in blood pressure, the vessel widening and the fast heartbeat that bradykinin causes ¹. The inhibition depended on dose and time ¹. The label adds that "the clinical significance of these findings is unknown" ¹. After an injection under the skin, nearly all of the dose reaches the blood ¹. The drug is cleared with a mean half-life, the time for the blood level to fall by half, of 1.4 hours ¹.

What does the research show?

The evidence for icatibant is at the top tier: FDA approval on three controlled trials, with 223 patients in the label's count ¹. Their mean age was 38 years, 64 percent were women and 95 percent were white ¹. Response was measured mainly on a visual analog scale, or VAS, a 100-millimeter line on which patients mark how bad a symptom is ¹.

Studied in people against placebo: FAST-3, a phase 3 (late-stage, pre-approval), randomized, double-blind, placebo-controlled trial published online in October 2011, enrolled 98 adults with a median age of 36 ³, ¹, ⁶. Randomized means patients were assigned to a treatment by chance, and double-blind that neither they nor their doctors knew which ³. Placebo-controlled means the comparison was an inactive injection ³.

Patients with moderate to severe skin or abdominal attacks, or mild to moderate laryngeal attacks, were randomized to icatibant or placebo ¹. Those with severe laryngeal attacks received icatibant open-label, meaning everyone knew what was given ¹. A laryngeal attack is swelling of the larynx, which can close the airway ¹.

The primary endpoint was the time to a 50 percent fall in a three-item VAS score of skin swelling, skin pain and abdominal pain ¹. Among patients with skin or abdominal attacks, the median was 2.0 hours in the 43 on icatibant and 19.8 hours in the 45 on placebo ³, ¹. The 95 percent confidence intervals were 1.5 to 3.0 hours and 6.1 to 26.3 hours ¹. The difference was statistically significant, with a p-value (the chance of a gap this large arising by luck) below 0.001 ¹.

Almost complete relief took a median of 8.0 hours against 36.0 hours ³, ¹. Rescue medication was used by 3 of 43 on icatibant (7 percent) and 18 of 45 on placebo (40 percent) ¹.

The paper adds two earlier time points. The first onset of symptom relief came at a median of 0.8 hours against 3.5 ³. Relief of the main symptom began at a median of 1.5 hours against 18.5 ³. For the five mild to moderate laryngeal attacks, three on icatibant and two on placebo, the median time to a 50 percent fall was 2.5 hours against 3.2 ³. Shire sponsored the trial, which ran from July 2009 to October 2010 ⁶.

Studied in people in two earlier trials: FAST-1 and FAST-2, both double-blind and randomized, were published together in August 2010 ⁴. FAST-1 randomized 56 patients with skin or abdominal attacks to icatibant or placebo, and FAST-2 randomized 74 to icatibant or tranexamic acid, a medicine taken by mouth ⁴. The primary endpoint was the median time to clinically significant relief ⁴. In FAST-1 it was 2.5 hours on icatibant against 4.6 on placebo, a difference that was not statistically significant, with a p-value of 0.14 ⁴. In FAST-2 it was 2.0 hours against 12.0 on tranexamic acid, significant, with a p-value below 0.001 ⁴.

In FAST-1, 3 patients on icatibant and 13 on placebo needed rescue medication ⁴. The authors wrote that "the early use of rescue medication may have obscured the benefit of icatibant in the placebo trial" ⁴. The time to first improvement, as judged by patients and by investigators, was significantly shorter with icatibant in both trials ⁴. Both were funded by Jerini ⁴.

The label reports the same two trials as a second placebo-controlled trial and an active-controlled trial, in which 26 and 35 patients received icatibant ¹. Across all three trials, it gives the median time to a 50 percent fall as 2.0 to 2.3 hours ¹.

Repeat attacks were treated in open-label extensions of all three trials: 225 patients received 1,076 doses for 987 attacks ¹. Over each patient's first five treated attacks, the median times to a 50 percent fall were similar, from 1.5 to 2.4 hours ¹. Ninety-three percent of attacks were treated with a single injection ¹. Sixty patients with laryngeal attacks were treated in the controlled trials, with results the label calls similar to those for skin and abdominal attacks ¹. In a separate open-label trial, 56 patients injected the drug themselves during an attack, with a median time to a 50 percent fall of 2.6 hours ¹.

None of the sources cited here studies icatibant for weight, muscle, skin aging or any wellness use ³, ¹, ⁴. Every treatment trial above enrolled patients with hereditary angioedema during an attack ³, ¹, ⁴.

What are the side effects?

Injection-site reactions lead, and nearly every trial patient had one ¹. The label says they "occurred in almost all patients (97%) in clinical trials" ¹. In the two placebo-controlled trials, 77 patients received icatibant and 75 placebo, and an injection-site reaction was reported by 75 (97 percent) against 25 (33 percent) ¹. The reactions listed include bruising, burning, redness, numbness, irritation, swelling, pain, itching, hives and warmth at the site ¹.

Three other reactions were more common than on placebo ¹. Fever occurred in 3 patients (4 percent) against none ¹. A rise in transaminases, liver enzymes measured in a blood test, occurred in 3 (4 percent) against none, and dizziness in 2 (3 percent) against 1 ¹. Rash, nausea and headache were reported in the open-label extensions ¹.

In FAST-3, adverse events of any kind occurred in 41 percent on icatibant and 52 percent on placebo ³. Every icatibant patient had an injection-site reaction, and none reported a serious adverse event ³. counts injection-site reactions against its 41 percent adverse-event rate is not stated in the abstract.] FAST-1 and FAST-2 reported no icatibant-related serious adverse events ⁴.

Four patients developed antibodies to icatibant across the controlled trials, and three of them later tested negative ¹. No hypersensitivity or anaphylactic reaction was reported with it in the trials, the label says ¹. Since approval, hives have been reported ¹. The label lists no contraindications, and the section reads "None" ¹.

The label's one warning concerns laryngeal attacks ¹. It reads: "Given the potential for airway obstruction during acute laryngeal HAE attacks, patients should be advised to seek medical attention in an appropriate healthcare facility immediately in addition to treatment with FIRAZYR" ¹. The label also says: "Tiredness, drowsiness, and dizziness have been reported following the use of FIRAZYR. Patients should be advised not to drive or use machinery if they feel tired or dizzy" ¹.

Two cautions rest on pharmacology and animal work. Because it blocks bradykinin, the label says icatibant "may attenuate the antihypertensive effect of ACE inhibitors," a common class of blood-pressure medicines ¹. The trials excluded people taking them ¹.

In isolated guinea pig and rat hearts, icatibant reduced coronary blood flow and prolonged the rhythm disturbances that follow the reopening of a blocked artery ¹. In anesthetized dogs with an induced heart attack, infusing it into the coronary artery doubled the death rate ¹. So the label says it "should be used during acute coronary ischemia, unstable angina pectoris, or in the weeks following a stroke only if the benefit exceeds the theoretical risk to the patient" ¹.

In pregnancy, the label says published literature and the pharmacovigilance database for Firazyr "have not identified a drug-associated risk of major birth defects, miscarriage or adverse maternal or fetal outcomes" ¹. Rabbits given it had more premature births and abortions ¹. Older adults had about twice the drug exposure of younger ones, with no difference in efficacy or safety identified ¹.

In sport

WADA's (the World Anti-Doping Agency's) 2026 Prohibited List names neither icatibant, Firazyr nor the bradykinin receptor antagonists ⁷. Icatibant holds FDA approval, granted in 2011 ².

What JumpstartMD offers

JumpstartMD does not prescribe icatibant. Our peptide library covers it so you have the facts on its FDA status and the evidence, current as of November 10, 2026.

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