B2 Receptor Antagonist Icatibant Research Articles

Therapeutic Polypeptides and Peptidomimetics: Powerful Tools for COVID-19 Treatment.

The coronavirus disease 2019 (COVID-19) pandemic has swept the whole world and brought about a public health crisis of unprecedented proportions. To combat the rapid transmission and possible deaths due to the disease, researchers and companies around the world are developing all possible strategies. Due to the advantages of safety, specificity, and fewer adverse effects, polypeptide and peptidomimetic drugs are considered promising strategies. This review comprehensively summarizes and discusses the progress in development of peptide drugs for use in the treatment of COVID-19. Based on the latest results in this field, we divided them into clinically approved drugs, clinical trial drugs, and clinically ineffective drugs, and outlined the molecular targets and mechanisms of action one by one to reveal their feasibility as promising therapeutic agents for COVID-19. Notably, monoclonal antibodies have shown beneficial effects in the early stages of infection, while Paxlovid can significantly reduce hospitalization and mortality among non-vaccinated patients. Among clinical experimental drugs, both the interleukin-1 receptor antagonist anakinra and the bradykinin B2 receptor antagonist icatibant are well tolerated and effective in patients with COVID-19, but long-term trials are needed to confirm the durability of efficacy.

Large Predominance of Off-Label Prescriptions of C1-Inhibitor Concentrates and Icatibant in a Real-Life Setting: A Retrospective Clinical Study.

C1-inhibitor (C1INH) concentrates and the selective bradykinin B2 receptor antagonist icatibant are approved only for treating hereditary angioedema with C1INH deficiency. Yet, they are regularly prescribed off label in other types of bradykinin-mediated angioedema including angiotensin-converting enzyme inhibitor (ACEi)-related and undetermined angioedema. We conducted a retrospective chart review of inpatient prescriptions of C1INH concentrates and icatibant between 2016 and 2020 in the University Hospital of Angers. The first outcome was the proportion of prescriptions with explicit indication. Then, we determined the compliance of prescriptions with European Medicines Agency approvals and the French bradykinin-mediated angioedema reference center guidelines. Finally, we estimated the economic impact of inappropriate prescribing. The therapeutic indication was explicit in 90.4% of prescriptions (n=66/73). Only 17.8% of prescriptions were for hereditary angioedema with C1INH deficiency, while 31.5% were for ACEi-related and 28.7% for undetermined angioedema. However, most off-label prescriptions were consistent with the French bradykinin-mediated angioedema reference center guidelines (73.3%). We estimated that 13% of drug expenditures were potentially excessive. The predominance of off-label prescriptions may be explained by the infrequency of hereditary angioedema and the absence of approved alternatives in other types of bradykinin-mediated angioedema. Most attacks were related to ACEis. Epinephrine was rarely prescribed as first-line therapy in attacks of unknown origin. Given the high prices of these drugs, we advocate the development of a readily available management algorithm of angioedema to reduce inappropriate prescriptions in our center. In addition, we think that the drug prescription circuit should be redesigned to ensure the traceability of prescribed vials in the dispensing areas.

Real-world off-label use of icatibant for acute management of non-hereditary angioedema.

We retrospectively examined the indications and efficacy of off-label use of the bradykinin B2 receptor antagonist icatibant. The clinical heterogeneity, variability of response to icatibant and lack of efficacy of adrenaline described in this audit highlights both the need for biomarkers that can rapidly distinguish between histaminergic and non-histaminergic angioedema, and for guidelines to improve the utility of icatibant in the non-hereditary angioedema setting.

In Vitro Modeling of Bradykinin-Mediated Angioedema States.

Kinins (peptides related to bradykinin, BK) are formed from circulating substrates, the kininogens, by the action of two proteases, the kallikreins. The only clinical application of a BK receptor ligand, the B2 receptor antagonist icatibant, is the treatment of the rare hereditary angioedema (HAE) caused by the deficiency of C1-esterase inhibitor (C1-INH). Less common forms of HAE (genetic variants of factor XII, plasminogen, kininogen) are presumably mediated by increased BK formation. Acquired forms of BK-mediated angioedema, such as that associated with angiotensin-I converting enzyme (ACE) inhibition, are also known. Antibody-based analytical techniques are briefly reviewed, and support that kinins are extremely short-lived, prominently cleared by ACE. Despite evidence of continuous activation of the kallikrein–kinin system in HAE, patients are not symptomatic most of the time and their blood or plasma obtained during remission does not generate excessive immunoreactive BK (iBK), suggesting effective homeostatic mechanisms. HAE-C1-INH and HAE-FXII plasmas are both hyperresponsive to fibrinolysis activation. On another hand, we suggested a role for the alternate tissue kallikrein–kinin system in patients with a plasminogen mutation. The role of the BK B1 receptor is still uncertain in angioedema states. iBK profiles under in vitro stimulation provide fresh insight into the physiopathology of angioedema.

Effect of bradykinin receptor antagonism on ACE inhibitor-associated angioedema

The B2 receptor antagonist icatibant is approved for treatment of attacks of hereditary angioedema. Icatibant has been reported to decrease time-to-resolution of angiotensin-converting enzyme (ACE) inhibitor-associated angioedema in 1 study of European patients. We sought to test the hypothesis that a bradykinin B2 receptor antagonist would shorten time-to-resolution from ACE inhibitor-associated angioedema. Patients with ACE inhibitor-associated angioedema (defined as swelling of lips, tongue, pharynx, or face during ACE inhibitor use and no swelling in the absence of ACE inhibitor use) were enrolled at Vanderbilt University Medical Center from October 2007 through September 2015 and at Massachusetts General Hospital in 2012. C1 inhibitor deficiency and patients with bowel edema only were excluded. Patients were randomized within 6hours of presentation to subcutaneous icatibant 30mg or placebo at 0 and 6hours later. Patients assessed severity of swelling using a visual analog scale serially following study drug administration or until discharge. Thirty-three patients were randomized and 31 received treatment, with 13 receiving icatibant and 18 receiving placebo. One patient randomized to icatibant did not complete the visual analog scale and was excluded from analyses. Two-thirds of patients were black and two-thirds were women. Time-to-resolution of symptoms was similar in placebo and icatibant treatment groups (P=.19 for the primary symptom and P>.16 for individual symptoms of face, lip, tongue, or eyelid swelling). Frequency of administration of H1 and H2 blockers, corticosteroids, and epinephrine was similar in the 2 treatment groups. Time-to-resolution of symptoms was similar in black and white patients. This study does not support clinical efficacy of a bradykinin B2 receptor antagonist in ACE inhibitor-associated angioedema.

Involvement of the TRPV1 receptor in plasma extravasation in airways of rats treated with an angiotensin-converting enzyme inhibitor

Angiotensin-converting enzyme inhibitors (ACEIs) are widely used in the treatment of hypertension, congestive heart failure and renal disease, and are considered relatively safe and generally well-tolerated drugs. However, adverse effects of ACEIs have been reported, including non-productive cough and angioedema, which can lead to poor adherence to therapy. The mechanisms by which ACEIs promote adverse effects are not fully elucidated, although increased bradykinin plasma levels following ACEI therapy seem to play an important role. Since bradykinin can sensitise the transient potential vanilloid receptor 1 (TRPV1), we investigated the role of TRPV1 in plasma extravasation in the trachea and bronchi of rats treated with the ACEI captopril. We observed that intravenous (i.v.) administration of captopril did not cause plasma extravasation in the trachea or bronchi of spontaneously breathing rats, but induced plasma extravasation in the trachea and bronchi of artificially ventilated rats. The intratracheal (i.t.) instillation of capsaicin or bradykinin also induced an increase in plasma extravasation in the trachea and bronchi of artificially ventilated rats. As expected, capsaicin-induced plasma extravasation was inhibited by i.t. pretreatment with the TRPV1 selective antagonist capsazepine (CPZ) while bradykinin-induced plasma extravasation was reduced by i.t. pretreatment with the selective B2 receptor antagonist Icatibant, originally known as HOE 140 (HOE). Interestingly, bradykinin-induced plasma extravasation was also inhibited by CPZ. The pretreatment with HOE and CPZ, singly or in combination and at doses which do not cause inhibitory effects per se, significantly inhibited the plasma extravasation induced by captopril treatment in artificially ventilated rats. In addition, treatment with a high dose of capsaicin in newborn rats, which induces degeneration of TRPV1-expressing sensory neurons, abolished both capsaicin and captopril-induced plasma extravasation in artificially ventilated rats. In conclusion, our study identified that captopril treatment promoted sensitisation of TRPV1, via B2 receptor activation, inducing plasma extravasation in the airways of mechanically ventilated rats. The present findings add a new view about the role of TRPV1 in the plasma extravasation induced by captopril and could to contribute to the elucidation of mechanisms by which ACEI induces adverse effects on airways.

Abstract P307: Effect of Bradykinin Receptor Antagonism on ACE Associated Angioedema

The B2 receptor antagonist icatibant is approved for treatment of attacks of hereditary angioedema. Icatibant has been reported to decrease time-to-resolution of ACE inhibitor-associated angioedema in one study of European patients. Patients with ACE inhibitor-associated angioedema (defined as swelling of lips, tongue, pharynx or face during ACE inhibitor use and no swelling in the absence of ACE inhibitor use) were randomized within six hours of presentation to SQ icatibant 30 mg or placebo at zero and six hours later. Patients assessed severity of swelling using a visual analog scale serially following study drug administration or until discharge. Thirty-one patients were randomized to and received treatment, with 13 receiving icatibant and 18 receiving placebo. One patient randomized to icatibant did not complete the visual analog scale and was excluded. Two-thirds of patients were African American and two-thirds were women. Time-to-resolution of symptoms was similar in placebo and icatibant treatment groups [p=0.19 for the primary symptom (Figure) and p>0.16 for individual symptoms of face, lip, tongue, or eyelid swelling]. Frequency of administration of H1 and H2 blockers, corticosteroids, and epinephrine was similar in the two treatment groups. Lip swelling was more severe in blacks (p=0.03), while tongue swelling was more severe in whites (0.02). White patients were significantly more likely to receive epinephrine (p=0.01). Time-to-resolution of symptoms was similar in blacks and whites. This study does not support the clinical efficacy of administration of a B 2 receptor blocker in black or white American patients with ACE inhibitor-associated angioedema.

Prophylaxis in hereditary angioedema (HAE) with C1 inhibitor deficiency.

Hereditary angioedema (HAE) is a rare congenital disorder characterized by recurrent episodes of subcutaneous or submucosal edema. Laryngeal manifestations can be life-threatening. In the majority of cases, the disease can be adequately treated with an on-demand approach--in some cases, however, short- or long-term prophylaxis is indicated. Attenuated androgens used to be the drugs of choice, but they are associated with considerable side effects and no longer commercially available in the German-speaking countries of the EU. They are currently being replaced by more effective and more tolerable agents such C1-inhibitors, the kallikrein inhibitor ecallantide, and the B2 receptor antagonist icatibant, which have recently obtained market authorization. These new drugs have had a major impact, especially on the indications and procedures for long-term prophylaxis. According to the most recent international consensus papers and our own experience, self-administered C1-inhibitors are now the first option for long-term prophylactic therapy. The decision for prophylaxis should no longer be based on single parameters such as the frequency of attacks but on adequate overall disease control including quality of life. More drugs are currently being developed, which may lead to further changes in the treatment algorithms of HAE.

Nanofiltrated C1-esterase-inhibitor in the prophylactic treatment of bradykinin-mediated angioedema.

Patients suffering from bradykinin-induced angioedema show recurrent swelling of subcutaneous and submucosal structures. Increased bradykinin levels lead to an increase in vascular permeability and edema formation. Current therapy consists of B2 bradykinin receptor antagonists, C1-esterase-inhibitor (C1-INH) concentrate, or the kallikrein inhibitor ecallantide. In most cases the treatment of acute attacks is sufficient. Prophylactic therapy is recommended only in severe cases. C1-INHc has been shown a safe and efficient option. Its effect on the quality of life has not yet been analyzed. Patients with inadequate disease control despite an "on-demand therapy" including C1-INHc and/or the B2 receptor antagonist icatibant were switched to long-term prophylaxis consisting in an individual dose of intravenous C1-INHc (Cinryze). None of the patients had been previously treated with ecallantide. Disease-specific quality-of-life questionnaires and patient records were used for evaluation. Disease control, quality of life, adverse events, and administered dosage per month were compared for 6 months on on-demand therapy and the following 6 months under prophylactic therapy. Data of seven patients with hereditary angioedema (HAE) and one patient with acquired angioedema were evaluated. Prophylactic therapy with Cinryze led to a significant and clinically relevant reduction in the overall attack frequency from 6.7 to 2.3 per month without relevant side effects. The frequency of severe attacks was reduced by 89% and quality of life significantly improved. Prophylaxis with Cinryze led to a significantly improved quality of life in our cohort of patients with high-frequency bradykinin-induced angioedema attacks that were not sufficiently treated with on-demand medication.

AT₂ receptor activation induces natriuresis and lowers blood pressure.

Compound 21 (C-21) is a highly selective nonpeptide AT2 receptor (AT2R) agonist. To test the hypothesis that renal proximal tubule AT2Rs induce natriuresis and lower blood pressure in Sprague-Dawley rats and mice. In rats, AT2R activation with intravenous C-21 increased urinary sodium excretion by 10-fold (P<0.0001); this natriuresis was abolished by direct renal interstitial infusion of specific AT2R antagonist PD-123319. C-21 increased fractional excretion of Na(+) (P<0.05) and lithium (P<0.01) without altering renal hemodynamic function. AT2R activation increased renal proximal tubule cell apical membrane AT2R protein (P<0.001) without changing total AT2R expression and internalized/inactivated Na(+)-H(+) exchanger-3 and Na(+)/K(+)ATPase. C-21-induced natriuresis was accompanied by an increase in renal interstitial cGMP (P<0.01); C-21-induced increases in urinary sodium excretion and renal interstitial cGMP were abolished by renal interstitial nitric oxide synthase inhibitor l-N(6)-nitroarginine methyl ester or bradykinin B2 receptor antagonist icatibant. Renal AT2R activation with C-21 prevented Na(+) retention and lowered blood pressure in the angiotensin II infusion model of experimental hypertension. AT2R activation initiates its translocation to the renal proximal tubule cell apical membrane and the internalization of Na(+)-H(+) exchanger-3 and Na(+)/K(+)ATPase, inducing natriuresis in a bradykinin-nitric oxide-cGMP-dependent manner. Intrarenal AT2R activation prevents Na(+) retention and lowers blood pressure in angiotensin II-dependent hypertension. AT2R activation holds promise as a renal proximal tubule natriuretic/diuretic target for the treatment of fluid-retaining states and hypertension.

Angioedema is not just ‘deep urticaria’ but an entity of its own

Angioedema is not just ‘deep urticaria’ but an entity of its own

Aliskiren Reduces Myocardial Ischemia–Reperfusion Injury by a Bradykinin B 2 Receptor– and Angiotensin AT 2 Receptor–Mediated Mechanism

Angiotensin-converting enzyme inhibitors and angiotensin AT1 receptor blockers reduce myocardial ischemia-reperfusion injury via bradykinin B2 receptor- and angiotensin AT2 receptor-mediated mechanisms. The renin inhibitor aliskiren increases cardiac tissue kallikrein and bradykinin levels. In the present study, we investigated the effect of aliskiren on myocardial ischemia-reperfusion injury and the roles of B2 and AT2 receptors in this effect. Female Sprague-Dawley rats were treated with aliskiren (10 mg/kg per day) and valsartan (30 mg/kg per day), alone or in combination, together with the B2 receptor antagonist icatibant (0.5 mg/kg per day) or the AT2 receptor antagonist PD123319 (30 mg/kg per day), for 4 weeks before myocardial ischemia-reperfusion injury. Aliskiren increased cardiac bradykinin levels and attenuated valsartan-induced increases in plasma angiotensin II levels. In vehicle-treated rats, myocardial infarct size (% area at risk, mean±SEM, n=7-13) was 43±3%. This was reduced to a similar extent by aliskiren, valsartan, and their combination to 24±3%, 25±3%, and 22±2%, respectively. Icatibant reversed the cardioprotective effects of aliskiren and the combination of aliskiren plus valsartan, but not valsartan alone, indicating that valsartan-induced cardioprotection was not mediated by the B2 receptor. PD123319 reversed the cardioprotective effects of aliskiren, valsartan, and the combination of aliskiren plus valsartan. Aliskiren protects the heart from myocardial ischemia-reperfusion injury via a B2 receptor- and AT2 receptor-mediated mechanism, whereas cardioprotection by valsartan is mediated via the AT2 receptor. In addition, aliskiren attenuates valsartan-induced increases in angiotensin II levels, thus preventing AT2 receptor-mediated cardioprotection by valsartan.

Icatibant in the treatment of Angiotensin-converting enzyme inhibitor-induced angioedema.

We describe the case of a 75-year-old woman who presented with massive tongue and lip swelling secondary to angiotensin-converting enzyme inhibitor-induced angioedema. An awake fibre-optic intubation was performed because of impending airway obstruction. As there was no improvement in symptoms after 72 hours, the selective bradykinin B2 receptor antagonist icatibant (Firazyr) was administered and the patient's trachea was successfully extubated 36 hours later. To our knowledge this is the first documented case of icatibant being used for the treatment of angiotensin-converting enzyme inhibitor-induced angioedema in the United Kingdom and represents a novel therapeutic option in its management.

Angiotensin II Type 2 Receptor–Mediated and Nitric Oxide–Dependent Renal Vasodilator Response to Compound 21 Unmasked by Angiotensin-Converting Enzyme Inhibition in Spontaneously Hypertensive Rats In Vivo

Angiotensin II type 2 receptor (AT2R)-mediated vasodilation has been demonstrated in different vascular beds in vitro and in perfused organs. In vivo studies, however, consistently failed to disclose renal vasodilator responses to compound 21, a selective AT2R agonist, even after angiotensin II type 1 receptor blockade. Here, we investigated in vivo whether angiotensin-converting enzyme inhibition, reducing endogenous angiotensin II levels, could unmask the effects of selective AT2R stimulation on blood pressure and renal hemodynamics in normotensive and hypertensive rats. After pretreatment with the angiotensin-converting enzyme inhibitor captopril, intravenous administration of compound 21 did not affect blood pressure and induced dose-dependent renal vasodilator responses in spontaneously hypertensive but not in normotensive rats. The D1 receptor agonist fenoldopam, used as positive control, reduced blood pressure and renal vascular resistance in both strains. The AT2R antagonist PD123319 and the nitric oxide synthase inhibitor L-NMMA (N(G)-monomethyl-L-arginine acetate) abolished the renal vasodilator response to compound 21 without affecting responses to fenoldopam. The cyclooxygenase inhibitor indomethacin partially inhibited the renal vascular response to compound 21, whereas the bradykinin B2 receptor antagonist icatibant was without effect. Angiotensin-converting enzyme inhibition unmasked a renal vasodilator response to selective AT2R stimulation in vivo, mediated by nitric oxide and partially by prostaglandins. AT2R may have a pathophysiological role to modulate renal hemodynamic effects of angiotensin II in the hypertensive state.

Abstract 473: Compound-21 Acts at Renal Proximal Tubule AT2 Receptors to Inhibit Na+ Reabsorption via Bradykinin, Nitric Oxide, and Cyclic GMP

Angiotensin (Ang) AT2 receptors (AT2Rs) are expressed in the kidney at vascular and tubular sites. Previous studies from our lab have shown that renal AT2R activation induces natriuresis and that Ang III is the endogenous agonist for this response. Compound 21 (C21) is a highly selective non-peptide AT2R agonist with approx. 25,000-fold selectivity for AT2Rs over AT1 receptors (AT1Rs). However, C21, particularly at high concentrations, has recently been shown to have AT2R-independent effects in the vasculature. We hypothesized that C21 induces natriuresis via AT2R translocation to the apical membrane and by activating a bradykinin (BK)-nitric oxide (NO)-cyclic GMP (cGMP) signaling pathway in the renal proximal tubule (RPT). In anesthetized, uninephrectomized, volume-expanded rats, intravenous (iv) C21 infusion (100, 200 and 300 ng/kg/min; each dose for 30 min) increased urinary Na+ excretion (UNaV) from 0.16±0.03 to 1.12±0.19, 1.51±0.08 and 2.03±0.21 μmol/min, respectively; all P &lt;0.001). This natriuretic response was not altered by 24 h subcutaneous infusion of AT1R antagonist candesartan (CAND; 0.01 mg/kg/min), but was abolished by renal interstitial (RI) infusion of specific AT2R antagonist PD-123319 (PD). Blood pressure was unaltered by C21 or PD, but was lower in CAND-infused rats (P &lt;0.0001). C21 infusion increased fractional excretion of Na+ (FENa) from 0.36±0.07 to 0.90±0.18% (P&lt;0.05) and lithium (FELi) from 30.2±3.3 to 57.2±5.2% (P &lt;0.01) without altering glomerular filtration rate or renal blood flow. Compared to control, C21 infusion increased RPT cell apical membrane AT2R protein (0.11±0.006 vs. 0.08±0.004 DU respectively) without changing total cell AT2R. C21-induced natriuresis was also accompanied by an increase in RI cGMP from 3.78±0.82 to 17.1±3.39 pmol/ml (P&lt;0.01). The C21-induced increases in both UNaV and RI cGMP were abolished by RI infusion of NO synthase inhibitor L-NAME or BK B2 receptor antagonist icatibant. The results demonstrate that C21 initiates AT2R translocation to the RPT cell apical membrane inducing natriuresis in a BK-NO-cGMP-dependent manner in the absence of concurrent AT1R blockade. C21 holds promise as a natriuretic/diuretic agent for the treatment of fluid retaining states and hypertension.

Hereditary Angioedema with Normal C1-INH (HAE Type III)

Hereditary angioedema (HAE) with normal C1 inhibitor (C1-INH), also known as HAE type III, is a familial condition only clinically recognized within the past three decades. Similar to HAE from C1-INH deficiency (HAE types I and II), affected individuals experience unpredictable angioedema episodes of the skin, gastrointestinal tract, and airway. Unique clinical features of HAE with normal C1-INH include the predominance of affected women, frequent exacerbation by estrogen, and a prominence of angioedema that involves the face and oropharynx. The underlying pathophysiology of HAE with normal C1-INH is poorly understood, but indirect evidence points to contact pathway dysregulation with bradykinin-mediated angioedema. Currently, evaluation is complicated by a lack of confirmatory laboratory testing such that clinical criteria must often be used to make the diagnosis of HAE with normal C1-INH. Factor XII mutations have been identified in only a minority of persons affected by HAE with normal C1-INH, limiting the utility of such analysis. To date, no controlled clinical studies have examined the efficacy of therapeutic agents for HAE with normal C1-INH, although published evidence supports frequent clinical benefit with medications shown effective in HAE due to C1-INH deficiency.

Icatibant Duration of Action During Bradykinin Challenge

Binding of bradykinin to bradykinin B2 receptors is the key mediator of hereditary angioedema (HAE) attacks. The duration of action of the bradykinin B2 receptor antagonist icatibant was measured by examining bradykinin-responsive pharmacodynamic (PD) endpoints.

Hereditary Angioedema: Management of Laryngeal Attacks

Hereditary angioedema (HAE) patients suffering from laryngeal attacks in the United States faced severely limited treatment options until 2008. These potentially life-threatening episodes occur in over one-half of the patients affected by HAE during their lifetimes. Acute therapy had been relegated to supportive care, intubation, and consideration of fresh frozen plasma (FFP)--the latter with the potential for actually accelerating the speed and severity of the swelling. In this article we will review the recently approved and emerging HAE treatments that have evolved from the recognition that bradykinin generation is the fundamental abnormality leading to attacks of angioedema. Acute therapy for laryngeal attacks will be discussed including purified plasma-derived C1 inhibitor (C1INH), recombinant C1INH, an inhibitor of plasma kallikrein (ecallantide), and a B2 receptor antagonist (icatibant). Prophylactic care has also been transformed from a reliance on attenuated androgens with their attendant side effects to C1INH replacement. The arrival of these novel therapies promises to transform the future management of HAE.

Tissue kallikrein increase endothelial progenitor cells via B2-PI 3-kinase/Akt pathway

ObjectiveTissue kallikrein (TK) has been demonstrated to improve neovasculogenesis after myocardial infarction (MI). In the present study, we examined whether TK plays a role in the peripheral endothelial progenitor cells...

Successful long‐term treatment with the bradykinin B2 receptor antagonist icatibant in a patient with hereditary angioedema

Hereditary angioedema (HAE) is a rare, autosomal dominant disorder caused by a C1-esterase inhibitor (C1-INH) deficiency (type 1) or qualitative defect (type 2). It is characterized by recurrent subcutaneous or submucosal edema attacks in various organs with a frequency from a few attacks to over one hundred attacks per year. We report on the treatment of 141 attacks in a patient with hereditary angioedema with the bradykinin B2 receptor antagonist icatibant. During the entire observation period, efficacy of icatibant was maintained and not altered due to repeated administrations. No systemic or cardiovascular side affects were observed. In the present case, icatibant proved to be an effective and safe drug for the symptomatic treatment of acute HAE attacks. Its efficacy was not impaired by repeated administrations over a three-year period in this patient.