Icatibant: a novel approach to the treatment of angioedema related to the use of angiotensin-converting enzyme inhibitors

Exploring the management of recurrent angioedema caused by different mechanisms

PURPOSE OF REVIEW

We aim to explore the most recent insights into the pathogenesis of recurrent angioedema caused by different mechanisms and then focus on the management and treatment approaches available.

RECENT FINDINGS

The recently developed DANCE consensus classification identifies five types of angioedema: mast cell-mediated (AE-MC), bradykinin-mediated, because of intrinsic vascular endothelium dysfunction (AE-VE), drug-induced (AE-DI), and due to unknown mechanisms (AE-UNK). These subtypes require different management with treatment choices targeting the main pathogenetic pathways involved in each form. For AE-MC and AE-BK, the therapeutic landscape has been significantly widened in recent years. Conversely, there is a lack of consensus for the hereditary forms because of newly discovered mutations ( factor 12 , plasminogen, kininogen-1 , myoferlin, angiopoietin-1 , heparan sulfate 3-O-sulfotransferase 6 ) and AE-UNK.

SUMMARY

Recurrent angioedema can present with or without wheals. Angioedema without wheals may be driven by bradykinin and/or mast cell mediators. The different forms respond to specific drugs and require a different management. For its potentially life-threatening and disfiguring features, angioedema should be promptly recognized and effectively treated. For this reason, enhancing awareness about various angioedema subtypes and their management provide a useful tool for the clinical practice.

Discovery of α-Amidobenzylboronates as Highly Potent Covalent Inhibitors of Plasma Kallikrein

Hereditary angioedema (HAE), a rare genetic disorder, is associated with uncontrolled plasma kallikrein (PKa) enzyme activity leading to the generation of bradykinin swelling in subcutaneous and submucosal membranes in various locations of the body. Herein, we describe a series of potent α-amidobenzylboronates as potential covalent inhibitors of PKa. These compounds exhibited time-dependent inhibition of PKa (compound 20 IC50 66 nM at 1 min, 70 pM at 24 h). Further compound dissociation studies demonstrated that 20 showed no apparent reversibility comparable to d-Phe-Pro-Arg-chloromethylketone (PPACK) (23), a known nonselective covalent PKa inhibitor.

Clinical Practice Statement: What is the Emergency Department Management of Patients with Angioedema Secondary to an ACE-Inhibitor?

BACKGROUND

Angioedema is a complication that has been reported in up to 1.0% of individuals taking angiotensin-converting enzyme inhibitors (ACE-Is). Importantly, the onset of angioedema can occur anywhere from hours to several years after initiation of therapy with ACE-Is. Although most cases of ACE-I-induced angioedema (ACE-I-AE) are self-limiting, a major clinical concern is development of airway compromise, which can potentially require emergent airway management. The underlying pathophysiology of ACE-I-AE is incompletely understood, but is considered to be due in large part to excess bradykinin. Numerous medications have been proposed for the treatment of ACE-I-AE. This article is an update to the 2011 Clinical Practice Committee (CPC) statement from the American Academy of Emergency Medicine.

METHODS

A literature search in PubMed was performed with search terms angioedema and ACE inhibitors from August 1, 2012 to May 13, 2019. Following CPC guidelines, articles written in English were identified and then underwent a structured review for evaluation.

RESULTS

The search parameters resulted in 323 articles. The abstracts of these articles were assessed independently by the reviewers, who determined there were 63 articles that were specific to ACE-I-AE, of which 46 were deemed appropriate for grading in the final focused review.

CONCLUSIONS

The primary focus for the treatment of ACE-I-AE is airway management. In the absence of high-quality evidence, no specific medication therapy is recommended for its treatment. If, however, the treating physician feels the patient's presentation is more typical of an acute allergic reaction or anaphylaxis, it may be appropriate to treat for those conditions. Any patient with suspected ACE-I-AE should immediately discontinue that medication.

Drugs frequently involved in inducing hypersensitivity reactions

Adverse drug reactions represent a major public health problem, both from an economic point of view and, mainly, from the point of view of the induced pathology (iatrogenic diseases), being difficult to differentiate from other pathological conditions or even from the treated disease. Thus, these aspects prevent the use of the first-choice drugs needed for a particular treatment, in different therapeutic classes: beta-lactam antibiotics; sulfonamides; macrolide antibiotics; quinolones; non-steroidal anti-inflammatories; corticosteroids; Angiotensin converting enzyme (ACE) inhibitors; general anesthetics; biological drugs; antiepileptic drugs etc. On the other hand, adverse drug reactions represent a major problem for both clinical practice and preclinical research, in order to develop new drugs. Hypersensitivity reactions mainly refer to the adverse effects that can be harmful, disturbing, and sometimes fatal, that appear under the conditions of a normal immune system, including allergies and autoimmune reactions, both triggered by an immunological-allergic mechanism. The main purpose of this paper is to review the main classes of drugs involved in inducing hypersensitivity reactions.

Evaluation and Management of Angioedema in the Emergency Department

Angioedema is defined by non-dependent, non-pitting edema that affects several different sites and is potentially life-threatening due to laryngeal edema. This narrative review provides emergency physicians with a focused overview of the evaluation and management of angioedema. Two primary forms include histamine-mediated and bradykinin-mediated angioedema. Histamine-mediated forms present similarly to anaphylaxis, while bradykinin-mediated angioedema presents with greater face and oropharyngeal involvement and higher risk of progression. Initial evaluation and management should focus on evaluation of the airway, followed by obtaining relevant historical features, including family history, medications, and prior episodes. Histamine-mediated angioedema should be treated with epinephrine intramuscularly, antihistaminergic medications, and steroids. These medications are not effective for bradykinin-mediated forms. Other medications include C1-INH protein replacement, kallikrein inhibitor, and bradykinin receptor antagonists. Evidence is controversial concerning the efficacy of these medications in an acute episode, and airway management is the most important intervention when indicated. Airway intervention may require fiberoptic or video laryngoscopy, with preparation for cricothyrotomy. Disposition is dependent on patient's airway and respiratory status, as well as the sites involved.

Treatment of Life-Threatening ACE-Inhibitor-Induced Angioedema

Incidence of angioedema associated with angiotensin-converting enzyme inhibitors (ACE-I) has been estimated at 0.1%-2.2% of patients receiving treatment. Despite the potential severity of this disease state, standardized treatment is lacking. Traditional pharmacotherapy options include medications that target inflammatory mediators and the angiotensin pathway. However, because ACE-I-induced angioedema is caused by accumulation of bradykinin, these medications fail to target the underlying pathophysiology. Recently, novel therapies that target the kallikrein-bradykinin pathway have been studied. These include icatibant, ecallantide, C1 esterase inhibitors, and fresh-frozen plasma. Recent randomized controlled trials exhibit contradictory results with the use of icatibant. This is a focused review on traditional and novel treatment strategies for ACE-I-induced angioedema.

Efficacy of Treatment of Non-hereditary Angioedema

Non-hereditary angioedema (AE) with normal C1 esterase inhibitor (C1INH) can be presumably bradykinin- or mast cell-mediated, or of unknown cause. In this systematic review, we searched PubMed, EMBASE, and Scopus to provide an overview of the efficacy of different treatment options for the abovementioned subtypes of refractory non-hereditary AE with or without wheals and with normal C1INH. After study selection and risk of bias assessment, 61 articles were included for data extraction and analysis. Therapies were described for angiotensin-converting enzyme inhibitor-induced AE (ACEi-AE), for idiopathic AE, and for AE with wheals. Described treatments consisted of ecallantide, icatibant, C1INH, fresh frozen plasma (FFP), tranexamic acid (TA), and omalizumab. Additionally, individual studies for anti-vitamin K, progestin, and methotrexate were found. Safety information was available in 26 articles. Most therapies were used off-label and in few patients. There is a need for additional studies with a high level of evidence. In conclusion, in acute attacks of ACEi-AE and idiopathic AE, treatment with icatibant, C1INH, TA, and FFP often leads to symptom relief within 2 h, with limited side effects. For prophylactic treatment of idiopathic AE and AE with wheals, omalizumab, TA, and C1INH were effective and safe in the majority of patients.

Icatibant Compared to Steroids and Antihistamines for ACE-Inhibitor-Induced Angioedema

Article chosen

Bas M, Greve J, Stelter K, et al. A Randomized Trial of Icatibant in ACE-Inhibitor-Induced Angioedema. N Engl J Med 2015;372:418-25. doi:10.1056/NEJMoa1312524.

Pharmacologic management of angioedema induced by angiotensin-converting enzyme inhibitors

Purpose

The published evidence on pharmacologic approaches to the management of angiotensin-converting enzyme inhibitor (ACEI)–induced angioedema is reviewed.

Summary

Angioedema is a serious, potentially life-threatening adverse effect of ACEI use. Although the underlying mechanism is not fully understood, excess bradykinin produced through a complex interplay between the kallikrein-kinin and renin-angiotensin-aldosterone systems is thought to play a major role. The nonallergic nature of the reaction renders traditional therapies (corticosteroids and antihistamines) ineffective because those agents do not modify the proposed pathophysiology. Fresh frozen plasma (FFP) provides kinase II, a protein that breaks down bradykinin. Case reports support FFP as a treatment for ACEI-induced angioedema, but no formal evaluations have been completed to date. Both ecallantide and complement 1 esterase (C1) inhibitor concentrate reduce bradykinin production through upstream inhibition of kallikrein. C1 inhibitor concentrate has been used successfully to manage ACEI-induced angioedema in a few reported cases, but robust supportive studies are lacking. Conversely, ecallantide has been evaluated in multiple randomized trials but has not been shown to offer advantages over traditional therapies. The use of icatibant, a direct antagonist of bradykinin B2 receptors, was reported to be beneficial in several case reports and in a small Phase II study, safely and rapidly reducing symptoms of ACEI-induced angioedema. An ongoing Phase III trial (NCT01919801) will better define the role of icatibant in the management of ACEI-induced angioedema.

Conclusion

FFP, C1 inhibitor, and icatibant appear to be safe and effective therapeutic options for the management of ACEI-induced angioedema, whereas it appears ecallantide should be avoided.

Life-threatening ACE inhibitor-induced angio-oedema successfully treated with icatibant: a bradykinin receptor antagonist

We present a case of a 75-year-old woman treated with an ACE inhibitor, who presented with angio-oedema of the tongue and had difficulty speaking. No symptoms of anaphylaxis or urticaria were present. The patient was treated intravenously with antihistamine and glucocorticoid in combination with adrenaline inhalations. After 6 h in the hospital the swelling progressed, and the patient was admitted to the intensive care unit and treated with one injection of icatibant-a bradykinin receptor antagonist. The patient reported subjective relief after 20-30 min and the swelling resolved within 2 h. Although the angio-oedema was potentially life threatening, the patient avoided intubation and mechanical ventilation. ACE inhibitor-induced angio-oedema is most likely caused by an accumulation of bradykinin and substance P. Consequently, a bradykinin receptor antagonist is the rational treatment of choice instead of antiallergic medications, which have no proven efficacy in this condition.

Off-Label Use of Agents for Management of Serious or Life-threatening Angiotensin Converting Enzyme Inhibitor–Induced Angioedema

Objective: To evaluate the place in therapy of fresh frozen plasma (FFP), C1 esterase concentrate (C1-INH), ecallantide, and icatibant in the management of angiotensin-converting enzyme inhibitor–induced angioedema (ACEI-IA). Data Sources: A literature search was performed using PubMed (1946 through August 2015) and Embase (<1966 through August 2015). References from identified articles were reviewed. Study Selection and Data Extraction: Consensus papers, practice guidelines, case reports/series, clinical trials, and meeting abstracts published in English and involving humans were included. Data Synthesis: No medications are currently Food and Drug Administration–approved for managing ACEI-IA. Emerging evidence suggests that FFP and medications approved for management of acute attacks of hereditary angioedema, another bradykinin-mediated event, may be effective for use in ACEI-IA. Positive efficacy results were reported with FFP and C1-INH while mixed results have been seen with ecallantide. Off-label icatibant has the most evidence supporting its use in ACEI-IA with rapid symptom resolution (10 minutes to 6 hours) and avoidance of intubation and tracheotomy in several cases. These agents were well-tolerated in ACEI-IA. Conclusion: ACEI-IA is typically a self-limiting event. First-line therapies include ACEI discontinuation, observation, and supportive medications (eg, corticosteroids, antihistamines, and epinephrine). Symptom progression can be life-threatening and may require interventions such as tracheotomy and intubation. Off-label use of FFP and medications approved for hereditary angioedema have resulted in rapid resolution of symptoms and avoidance of intubation. Among these agents, icatibant has the most supporting evidence and has been incorporated into practice guidelines and algorithms as a second-line agent for serious life-threatening ACE-IA.

Treatment of ACEI-related angioedema with icatibant: a case series

No specific drugs are licensed for the treatment of ACE inhibitor (ACEI)-acquired angioedema (ACEI-AAE). Icatibant, an antagonist of the B2 receptor of bradykinin, is a potential treatment for this condition; however, its use in this setting is poorly documented. We report here clinical outcomes of 13 patients with ACEI-AAE treated with icatibant, in a real-life setting. Thirteen patients on ACEI seen in an Emergency Department (ED) with angioedema involving face, lips or the upper airways were analyzed. Angioedema due to known causes other than ACEI treatment was excluded. Initially, all patients received standard therapy (antihistamine, corticosteroids and epinephrine). Due to the lack of response and a worsening severity of symptoms, all patients received one subcutaneous injection of icatibant (30 mg/mL). Following icatibant treatment, all patients experienced improvement in the symptoms. The median time from onset of clinical symptoms to injection of icatibant was 3 h (IQR 2.5-5.5 h). Symptom relief was reported at 30 min (IQR 27.5-70 min). A complete resolution of symptoms was observed at 5 h (IQR 4-7 h). Ten patients had previously experienced angioedema attacks. The Median time to complete resolution of the previous attacks was higher (54 h; IQR 33-63 h), than after icatibant (p = 0.002) therapy. No patients required tracheal intubation or tracheotomy, and all patients were discharged within 24 h. No adverse events were reported. Before discharge, all patients were instructed to discontinue ACEI, and to take a different antihypertensive agent. This case series supports the efficacy of icatibant in improving symptoms of ACEI-AAE.

Angiotensin-converting enzyme inhibitor-induced angioedema

Angiotensin-converting enzyme inhibitors (ACE-I) are widely used, effective, and well-tolerated antihypertensive agents. The mechanisms by which those agents act can cause side effects such as decreased blood pressure, hyperkalemia, and impaired renal function. ACE-I can induce cough in 5%-35% and angioedema in up to 0.7% of treated patients. Because cough and angioedema are considered class adverse effects, switching treatment to other ACE-I agents is not recommended. Angioedema due to ACE-I has a low fatality rate, although deaths have been reported when the angioedema involves the airways. Here, we review the role of bradykinin in the development of angioedema in patients treated with ACE-I, as well as the incidence, risk factors, clinical presentation, and available treatments for ACE-I-induced angioedema. We also discuss the risk for recurrence of angioedema after switching from ACE-I to angiotensin receptor blockers treatment.

A randomized trial of icatibant in ACE-inhibitor-induced angioedema

BACKGROUND

Angioedema induced by treatment with angiotensin-converting-enzyme (ACE) inhibitors accounts for one third of angioedema cases in the emergency room; it is usually manifested in the upper airway and the head and neck region. There is no approved treatment for this potentially life-threatening condition.

METHODS

In this multicenter, double-blind, double-dummy, randomized phase 2 study, we assigned patients who had ACE-inhibitor-induced angioedema of the upper aerodigestive tract to treatment with 30 mg of subcutaneous icatibant, a selective bradykinin B2 receptor antagonist, or to the current off-label standard therapy consisting of intravenous prednisolone (500 mg) plus clemastine (2 mg). The primary efficacy end point was the median time to complete resolution of edema.

RESULTS

All 27 patients in the per-protocol population had complete resolution of edema. The median time to complete resolution was 8.0 hours (interquartile range, 3.0 to 16.0) with icatibant as compared with 27.1 hours (interquartile range, 20.3 to 48.0) with standard therapy (P=0.002). Three patients receiving standard therapy required rescue intervention with icatibant and prednisolone; 1 patient required tracheotomy. Significantly more patients in the icatibant group than in the standard-therapy group had complete resolution of edema within 4 hours after treatment (5 of 13 vs. 0 of 14, P=0.02). The median time to the onset of symptom relief (according to a composite investigator-assessed symptom score) was significantly shorter with icatibant than with standard therapy (2.0 hours vs. 11.7 hours, P=0.03). The results were similar when patient-assessed symptom scores were used.

CONCLUSIONS

Among patients with ACE-inhibitor-induced angioedema, the time to complete resolution of edema was significantly shorter with icatibant than with combination therapy with a glucocorticoid and an antihistamine. (Funded by Shire and the Federal Ministry of Education and Research of Germany; ClinicalTrials.gov number, NCT01154361.).

Drug-induced angioedema: experience of Italian emergency departments

Acute angioedema represents a cause of admission to the emergency department requiring rapid diagnosis and appropriate management to prevent airway obstruction. Several drugs, including angiotensin-converting enzyme inhibitors (ACE-I), nonsteroidal anti-inflammatory drugs (NSAIDs) and oral antidiabetics, have been reported to induce angioedema. The aim of this prospective observational study conducted in a setting of routine emergency care was to evaluate the incidence and extent of drug-induced non-histaminergic angioedema in this specific clinical setting, and to identify the class of drugs possibly associated with angioedema. Patients admitted to seven different emergency departments (EDs) in Rome with the diagnosis of angioedema and urticaria were enrolled during a 6-month period. Of the 120,000 patients admitted at the EDs, 447 (0.37 %) were coded as having angioedema and 655 (0.5 %) as having urticaria. After accurate clinical review, 62 cases were defined as drug-induced, non-histaminergic angioedema. NSAIDs were the most frequent drugs (taken by 22 out of 62 patients) associated with the angioedema attack. Of the remaining patients, 15 received antibiotic treatment and 10 antihypertensive treatment. In addition, we observed in our series some cases of angioedema associated with drugs (such as antiasthmatics, antidiarrheal and antiepileptics) of which there are few descriptions in the literature. The present data, which add much needed information to the existing limited literature on drug-induced angioedema in the clinical emergency department setting, will provide more appropriate diagnosis and management of this potentially life-threatening adverse event.

Guidance for diagnosis and treatment of acute angioedema in the emergency department: consensus statement by a panel of Italian experts

Angioedema attacks, characterized by the transient swelling of the skin and mucosae, are a frequent cause of visits to the emergency department. Swellings of the oral cavity, tongue, or larynx can result in life-threatening airway obstruction, while abdominal attacks can cause severe pain and often lead to unnecessary surgery. The underlying pathophysiologic process resulting in increased vascular permeability and plasma extravasation is mediated by vasoactive molecules, most commonly histamine and bradykinin. Based on the mediator involved, distinct angioedema forms can be recognized, calling for distinct therapeutic approaches. Prompt recognition is challenging for the emergency physician. The low awareness among physicians of the existence of rare forms of angioedema with different aetiologies and pathogenesis, considerably adds to the problem. Also poorly appreciated by emergency personnel may be the recently introduced bradykinin-targeted treatments. The main objective of this consensus statement is to provide guidance for the management of acute angioedema in the emergency department, from presentation to discharge or hospital admission, with a focus on identifying patients in whom new treatments may prevent invasive intervention.

Diagnosis and Treatment of Bradykinin-Mediated Angioedema: Outcomes from an Angioedema Expert Consensus Meeting

Several types of angioedema exist beyond hereditary angioedema (HAE) types I/II; however, the diagnostic and treatment needs of these conditions are not well understood. Noticeably, there are no licensed treatments available for other forms of angioedema beyond HAE types I/II, and similarly they are unresponsive to conventional antihistamine/glucocorticoid treatment. A group of angioedema experts met in Budapest in May 2013 to discuss such issues, presenting their experience, reviewing available literature and identifying unmet diagnostic and treatment needs in three different angioedema types: HAE with normal C1-inhibitor (C1-INH; previously referred to as type III HAE); nonallergic angiotensin-converting enzyme inhibitor (ACEI)-induced angioedema (ACEI-AAE), and acquired angioedema due to C1-INH deficiency (C1-INH-AAE). The group identified unmet diagnostic and treatment needs in HAE-nC1-INH, C1-INH-AAE and ACEI-AAE, explored remedies and made recommendations on how to diagnose and treat these forms of angioedema. The group discussed the difficulties associated with using diagnostic markers, such as the level and function of C1-INH, C1q and C4 to reliably diagnose the angioedema type, and considered the use of genetic testing to identify mutations in <i>FXII</i> or <i>XPNPEP2 </i>that have been associated with HAE-nC1-INH and ACEI-AAE, respectively. Due to the lack of approved treatments for HAE-nC1-INH, ACEI-AAE and C1-INH-AAE, the group presented several case studies in which therapies approved for treatment of HAE types I/II, such as icatibant, ecallantide and pasteurized, nanofiltered C1-INH, were successful. It was uniformly agreed that further studies are needed to improve the diagnosis and treatment of angioedema other than HAE types I/II. i 2014 S. Karger AG, Basel

Hereditary angioedema: epidemiology, management, and role of icatibant

Hereditary angioedema (HAE) is an autosomal dominant, potentially life-threatening condition, manifesting as recurrent and self-limiting episodes of facial, laryngeal, genital, or peripheral swelling with abdominal pain secondary to intra-abdominal edema. The estimated prevalence of HAE in the general population is one individual per 50,000, with reported ranges from 1:10,000 to 1:150,000, without major sex or ethnic differences. Various treatment options for acute attacks and prophylaxis of HAE are authorized and available in the market, including plasma-derived (Berinert®, Cinryze®, and Cetor®) and recombinant (Rhucin® and Ruconest™) C1 inhibitors, kallikrein inhibitor-ecallantide (Kalbitor®), and bradykinin B2 receptor antagonist-icatibant (Firazyr®). Some of these drugs are used only to treat HAE attacks, whereas others are only approved for prophylactic therapies and all of them have improved disease outcomes due to their different mechanisms of action. Bradykinin and its binding to B2 receptor have been demonstrated to be responsible for most of the symptoms of HAE. Thus icatibant (Firazyr®), a bradykinin B2 receptor antagonist, has proven to be an effective and more targeted treatment option and has been approved for the treatment of acute attacks of HAE. Rapid and stable relief from symptoms of cutaneous, abdominal, or laryngeal HAE attacks has been demonstrated by 30 mg of icatibant in Phase III clinical trials. Self-resolving mild to moderate local site reactions after subcutaneous injection of icatibant were observed. Icatibant is a new, safe, and effective treatment for acute attacks of HAE. HAE has been reported to result in enormous humanistic burden to patients, affecting both physical and mental health, with a negative impact on education, career, and work productivity, and with substantial economic burdens. The timely and proper use of disease-specific treatments could improve patients’ quality of life, reduce the disease-specific morbidity and mortality, and, last but not least, reduce costs associated with hospitalizations and emergency room visits. Therefore, the paradigm of HAE treatment has the potential to evolve significantly, thereby exponentially improving a patient’s quality of life.

Factors associated with hospitalization of patients with angiotensin-converting enzyme inhibitor-induced angioedema

Angiotensin-converting enzyme inhibitor (ACE-I)-induced angioedema can be life-threatening without emergent intervention. The putative mediator is believed to be bradykinin, similar to hereditary angioedema, so these patients respond poorly to corticosteroids and antihistamines. This study was designed to determine characteristics and clinical outcomes of patients presenting to an emergency department (ED) with ACE-I angioedema. This was a retrospective chart review of 100 patients presenting to the ED from 2007 to 2008 with an ICD-9 code of 995.1 (angioedema) or 995.2 (drug-induced angioedema). Two hundred fifty-two patients with these ICD-9 codes were identified and placed in random order, and the first 100 meeting inclusion criteria were included. Statistical analysis was primarily descriptive. All 100 patients had an ICD-9 code of 995.1 (angioedema). Patients presented in every month, with spring months (April-June) having the most presentations (32%). The median age was 59 years, 75% were African American, and 66% were admitted to the hospital. Two patients (2%) required endotracheal intubation. Lisinopril was the most commonly prescribed ACE-I (84%). The most common symptom was moderate lip and tongue swelling (89%) followed by mild difficulty breathing (12%). Tongue swelling was significantly associated with admission. Time from symptom onset to ED presentation was not associated with need for admission. Concomitant medications did not differ between admitted and discharged patients. ACE-I angioedema is associated with significant morbidity and health care use because many patients require hospitalization, suggesting an unmet need for novel therapies targeted to treat this condition.

An evidence-based review of the potential role of icatibant in the treatment of acute attacks in hereditary angioedema type I and II

INTRODUCTION

Icatibant, a first-in-class B2 bradykinin receptor antagonist, appears to have a favorable efficacy and safety profile for the treatment of acute attacks of hereditary angioedema in adults.

AIMS

To update the evidence and provide an overview of the available data on icatibant.

EVIDENCE REVIEW

Peer reviewed articles published and listed in Medline Search and published updated guidelines for the treatment of acute attacks in hereditary angioedema type I and II in adults were reviewed. The validity and quality of evidence were evaluated.

PLACE IN THERAPY

Clinical evidence for the treatment of acute hereditary angioedema attacks with icatibant is strong. Approximately 10% of the patients require a second dose. No serious adverse reactions have been reported. The only significant side effects consistently registered by 90% of patients are transient local pain, swelling, and erythema at the local injection site.

CONCLUSION

Subcutaneously administered 30 mg icatibant has been shown to be a safe and efficacious treatment in clinical trials. It is the only specific treatment authorized for self-administration by the subcutaneous route offering increased patient independence.

Drug allergy: causes and desensitization

Allergic drug reactions occur when a drug, usually a low molecular weight molecule, has the ability to stimulate an immune response. This can be done in one of two ways. The first is by binding covalently to a self-protein, to produce a haptenated molecule that can be processed and presented to the adaptive immune system to induce an immune response. Sometimes the drug itself cannot do this but a reactive breakdown product of the drug is able to bind covalently to the requisite self-protein or peptide. The second way in which drugs can stimulate an immune response is by binding non-covalently to antigen presenting or antigen recognition molecules such as the major histocompatibility complex (MHC) or the T cell receptor. This is known as the p-I or pharmacological interaction hypothesis. The drug binding in this situation is reversible and stimulation of the response may occur on first exposure, not requiring previous sensitization. There is probably a dependence on the presence of certain MHC alleles and T cell receptor structures for this type of reaction to occur.