Bradykinin 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.

Penicillin causes non-allergic anaphylaxis by activating the contact system

Immediate hypersensitivity reaction (IHR) can be divided into allergic- and non-allergic-mediated, while “anaphylaxis” is reserved for severe IHR. Clinically, true penicillin allergy is rare and most reported penicillin allergy is “spurious”. Penicillin-initiated anaphylaxis is possible to occur in skin test- and specific IgE-negative patients. The contact system is a plasma protease cascade initiated by activation of factor XII (FXII). Many agents with negative ion surface can activate FXII to drive contact system. Our data showed that penicillin significantly induced hypothermia in propranolol- or pertussis toxin-pretreated mice. It also caused a rapid and reversible drop in rat blood pressure, which did not overlap with IgE-mediated hypotension. These effects could be countered by a bradykinin-B2 receptor antagonist icatibant, and consistently, penicillin indeed increased rat plasma bradykinin. Moreover, penicillin not only directly activated contact system FXII-dependently, but also promoted bradykinin release in plasma incubated-human umbilical vein endothelial cells. In fact, besides penicillin, other beta-lactams also activated the contact system in vitro. Since the autoactivation of FXII can be affected by multiple-factors, plasma from different healthy individuals showed vastly different amidolytic activity in response to penicillin, suggesting the necessity of determining the potency of penicillin to induce individual plasma FXII activation. These results clarify that penicillin-initiated non-allergic anaphylaxis is attributed to contact system activation, which might bring more effective diagnosis options for predicting penicillin-induced fatal risk and avoiding costly and inappropriate treatment clinically.

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

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.

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.

At-Home Treatment of Patients with Acute Attacks of Hereditary Angioedema with the Bradykinin B2 Receptor-Antagonist Icatibant

At-Home Treatment of Patients with Acute Attacks of Hereditary Angioedema with the Bradykinin B2 Receptor-Antagonist Icatibant

Treatment of angiotensin-converting enzyme inhibitor–related angioedema with the bradykinin B2 receptor antagonist icatibant

Treatment of angiotensin-converting enzyme inhibitor–related angioedema with the bradykinin B2 receptor antagonist icatibant

Therapeutic Efficacy of Icatibant in Angioedema Induced by Angiotensin-Converting Enzyme Inhibitors: A Case Series

The pathophysiology of angiotensin-converting enzyme inhibitor (ACEi)-induced angioedema most likely resembles that of hereditary angioedema, ie, it is mainly mediated by bradykinin-induced activation of vascular bradykinin B2 receptors. We hypothesize that the bradykinin B2 receptor antagonist icatibant might be an effective therapy for ACEi-induced angioedema. Eight patients with acute ACEi-induced angioedema were treated with a single subcutaneous injection of icatibant. The outcome was assessed by the time to first improvement of symptoms, complete symptom relief, and drug safety. In addition, we retrospectively assessed the clinical course of 47 consecutive patients of our clinic with ACEi-induced angioedema. First symptom improvement after icatibant injection occurred at a mean time of 50.6 minutes (standard deviation [SD] 21 minutes) and complete relief of symptoms at 4.4 hours (SD 0.8 hours). No patient received tracheal intubation, other drug treatment, tracheotomy, or a second icatibant injection. There were no adverse effects except erythema occurring at the injection site. In the historical comparison group treated with methylprednisolone and clemastine, the mean time to complete relief of symptoms was 33 hours (SD 19.4 hours). Some of these patients received a tracheotomy (3/47), were intubated (2/47), or received a second dose of methylprednisolone (12/47). Although sample size limits the external validity of our results, the substantial decrease of time to complete symptom relief suggests that this new treatment is likely effective as a pharmacotherapeutic approach to treat ACEi-induced angioedema.

Successful treatment of hereditary angioedema with bradykinin B2‐receptor antagonist icatibant

The bradykinin B2 receptor antagonist icatibant has recently become available for treating hereditary angioedema. Our observations demonstrate icatibant to be effective and safe for the treatment of both, abdominal and cutaneous attacks in a practice setting beyond clinical studies.

Neuroprotection against Retinal Ischemia–Reperfusion Injury by Blocking the Angiotensin II Type 1 Receptor

PURPOSE. To investigate the effects of an angiotensin-converting enzyme (ACE) inhibitor and an angiotensin II antagonist against retinal ischemia-reperfusion injury in the rat retina. METHODS. Retinal ischemia was induced by increasing intraocular pressure to 130 mm Hg. Rats were treated with an ACE inhibitor (captopril), an angiotensin II type 1 receptor (AT1-R) antagonist (candesartan), an AT2-R antagonist (PD123319), bradykinin, or a bradykinin B2 receptor antagonist (icatibant). At 7 days after the ischemia, retinal damage was evaluated. Immunohistochemistry and image analysis were used to measure changes in the levels of reactive oxygen species (ROS) and the localization of AT1-R. Dark-adapted full-field electroretinography (ERG) was also performed. RESULTS. Pretreatment with captopril or candesartan significantly inhibited the ischemic injury of the inner retina. However, PD123319, bradykinin, or icatibant did not reduce the ischemic damage. In control retinas, retinal vessels were positive for AT1-R. In contrast, 12 hours after ischemia, immunohistochemical analysis detected numerous AT1-R-positive cells in the inner retina in vehicle-treated rats. After ischemia, the production of ROS was detected in retinal cells. However, pretreatment with captopril or candesartan suppressed the production of ROS. On the seventh postoperative day, the amplitudes of the ERG b-waves were significantly lower in the vehicle group than in the groups pretreated with captopril or candesartan. CONCLUSIONS. The present findings demonstrate that ischemic damage promotes the expression of AT1-R in the inner retina. Both the ACE inhibitor and the AT1-R antagonist that were examined can block the stimulation of the AT1-R and attenuate the subsequent ischemic damage in the rat retina.

Successful Treatment of 103 Attacks of Hereditary Hngioedema (HAE) with Bradykinin B2 Receptor Antagonist Icatibant

Bradykinin, via its B2 receptor, is the most important mediator of HAE attacks. Icatibant is a highly specific antagonist for the B2 receptor and has been previously shown to be effective in the treatment of HAE attacks.

Suppression of Choroidal Neovascularization by Inhibiting Angiotensin-Converting Enzyme: Minimal Role of Bradykinin

Angiotensin-converting enzyme (ACE), also known as kininase II, functions not only to convert angiotensin I to angiotensin II, but also to cleave bradykinin into inactive fragments. Thus, ACE inhibition causes the tissue accumulation of bradykinin, exerting either of two opposite effects: anti- or proangiogenic. The purpose of the present study was to investigate the role of bradykinin in the development of choroidal neovascularization (CNV), with or without ACE inhibition. Laser photocoagulation was used to induce CNV in wild-type C57BL/6J mice and angiotensin II type 1 receptor (AT1-R)-deficient mice. Wild-type mice were pretreated with the ACE inhibitor imidapril, with or without the bradykinin B2 receptor (B2-R) antagonist icatibant daily for 6 days before photocoagulation, and the treatment was continued daily until the end of the study. CNV response was analyzed by volumetric measurements using confocal microscopy 1 week after laser injury. The mRNA and protein levels of vascular endothelial growth factor (VEGF), intercellular adhesion molecule (ICAM)-1, and monocyte chemotactic protein (MCP)-1 in the retinal pigment epithelium-choroid complex were examined by RT-PCR and ELISA, respectively. ACE inhibition led to significant suppression of CNV development to the level seen in AT1-R-deficient mice. B2-R blockade together with high-dose but not low-dose ACE inhibition resulted in more potent suppression of CNV than did ACE inhibition alone. B2-R blockade alone exhibited little or no effect on CNV. VEGF, ICAM-1, and MCP-1 levels, elevated by CNV induction, were significantly suppressed by ACE inhibition. VEGF but not ICAM-1 or MCP-1 levels were further attenuated by B2-R blockade with ACE inhibition. These results suggest a limited contribution of the kallikrein-kinin system to the pathogenesis of CNV, in which the renin-angiotensin system plays more essential roles for facilitating angiogenesis. The present study indicates the possibility of ACE inhibition as a novel therapeutic strategy to inhibit CNV.

A novel therapeutic concept for the treatment of acute angioedema attacks in hereditary angioedema patients: multiple successful treatments even in severe swelling attacks with the bradykinin-B2 receptor antagonist Icatibant

Several forms of angioedema seem to be induced by elevated bradykinin (BK) concentrations. They are either caused by increased BK production, as is the case in hereditary angioedema (HAE) involving the lack of a functional C1-esterase inhibitor, or by reduced BK inactivation (e.g. during ACE-inhibitor treatment). BK-induced angioedema does not respond to the current standard treatment for angioedema caused by increased histamine levels, corticosteroids and antihistamines. Until now acute attacks of HAE have been treated with intravenously administered C1-esterase inhibitor concentrate derived from human plasma. However, no specific treatment has been approved for ACE-inhibitor-induced angioedema. It would be necessary that such an approach inhibits directly the activation of the bradykinin-B2 receptor by BK. During the ongoing international phase III HAE study FAST2, we treated several HAE patients subcutaneously with Icatibant, a specific bradykinin-B2 receptor antagonist. In the open-label part of this study we administered Icatibant for the treatment of 21 acute HAE attacks. Eleven attacks were located in the head-neck region, of which three involved the laryngeal area, six the abdominal and four the genital area. Following treatment with Icatibant, patients reported rapid onset of symptom relief and complete remission of symptoms within a few hours. We were especially impressed by the successful treatment of the edema involving the laryngeal area. The study drug was safe and well tolerated. We have noted short-lived local injection site reactions, which resolved spontaneously without intervention. In our hands Icatibant showed high efficacy for the treatment of acute HAE attacks with a rapid onset of symptom relief. Subcutaneous administration might improve the quality of life for HAE patients. Icatibant could also represent a new therapeutic paradigm for the treatment of ACE-inhibitor-induced angioedema cases but this hypothesis needs to be tested in a clinical study.