Current and emerging management options for hereditary angioedema in the US

Summary and future of medicine for hereditary angioedema

Hereditary angioedema (HAE) is a rare autosomal genetic disease for which there are currently nine FDA-approved drugs. This review summarizes drug treatments for HAE based on four therapeutic pathways: inhibiting the contact system, inhibiting bradykinin binding to B2 receptors, supplying missing C1 inhibitors, and inhibiting plasminogen conversion. The review generalizes the clinical use, pharmacological effects and mechanisms of HAE drugs, and it also discusses possible development directions and targets to enhance understanding of HAE and help researchers.

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.

The effect on the immunology laboratory of the expansion in complement therapeutics

The approval in the US and Europe of Eculizumab in 2007 marked a change in complement therapeutics, and with it the landscape for complement testing in the clinical immunology laboratory changed. The change had begun even before that when C1-Inhibitor preparations were approved in the 1980s in Europe. There are now two classes of approved drugs that may impact the immunology laboratory, with two dozen more with novel modalities and potential indications that are in various stages of development. Every pathway and about every component of complement has been targeted by these drug development programs, and the modalities of the drugs in development are diverse. These developments will likely result in more laboratories offering more complement testing, so this review looks forward to some of those possible changes in testing.

Current and future therapies for the treatment of histamine-induced angioedema

INTRODUCTION

Angioedema, a sudden, self-limited swelling of localized areas of any part of the body that may or may not be associated with urticaria, is thought to be the result of a mast-cell mediated process versus a bradykinin etiology. Understanding the mechanism is key in determining the proper treatment. Areas Covered: Clinical presentation of varying angioedema types may be similar; however, the appropriate treatment algorithm is dependent upon clinicians' knowledge of the underlying pathophysiology and classification of angioedema. Literature review of recent guidelines, available medications, and alternative therapies was completed to provide an overview of options.

CONCLUSION

There are no formal guidelines for treatment of acute or chronic histamine-mediated angioedema, and therefore, algorithms for the treatment of acute and chronic urticaria should be followed until such information becomes available. Differentiating histamine-mediated versus bradykinin mediated angioedema is essential, as treatments and treatment responses are quite different. Further research is needed to better understand idiopathic angioedema that is unresponsive to H1/H2 antagonists, LTMAs, or medications designed to treat bradykinin-mediated angioedema.

Hereditary angioedema: what the gastroenterologist needs to know

Up to 93% of patients with hereditary angioedema (HAE) experience recurrent abdominal pain. Many of these patients, who often present to emergency departments, primary care physicians, general surgeons, or gastroenterologists, are misdiagnosed for years and undergo unnecessary testing and surgical procedures. Making the diagnosis of HAE can be challenging because symptoms and attack locations are often inconsistent from one episode to the next. Abdominal attacks are common and can occur without other attack locations. An early, accurate diagnosis is central to managing HAE. Unexplained abdominal pain, particularly when accompanied by swelling of the face and extremities, suggests the diagnosis of HAE. A family history and radiologic imaging demonstrating edematous bowel also support an HAE diagnosis. Once HAE is suspected, C4 and C1 esterase inhibitor (C1-INH) laboratory studies are usually diagnostic. Patients with HAE may benefit from recently approved specific treatments, including plasma-derived C1-INH or recombinant C1-INH, a bradykinin B2-receptor antagonist, or a kallikrein inhibitor as first-line therapy and solvent/detergent-treated or fresh frozen plasma as second-line therapy for acute episodes. Short-term or long-term prophylaxis with nanofiltered C1-INH or attenuated androgens will prevent or reduce the frequency and severity of episodes. Gastroenterologists can play a critical role in identifying and treating patients with HAE, and should have a high index of suspicion when encountering patients with recurrent, unexplained bouts of abdominal pain. Given the high rate of abdominal attacks in HAE, it is important for gastroenterologists to appropriately diagnose and promptly recognize and treat HAE, or refer patients with HAE to an allergist.

A consensus parameter for the evaluation and management of angioedema in the emergency department

Despite its relatively common occurrence and life-threatening potential, the management of angioedema in the emergency department (ED) is lacking in terms of a structured approach. It is paramount to distinguish the different etiologies of angioedema from one another and more specifically differentiate histaminergic-mediated angioedema from bradykinin-mediated angioedema, especially in lieu of the more novel treatments that have recently become available for bradykinin-mediated angioedema. With this background in mind, this consensus parameter for the evaluation and management of angioedema attempts to provide a working framework for emergency physicians (EPs) in approaching the patient with angioedema in terms of diagnosis and management in the ED. This consensus parameter was developed from a collaborative effort among a group of EPs and leading allergists with expertise in angioedema. After rigorous debate, review of the literature, and expert opinion, the following consensus guideline document was created. The document has been endorsed by the American College of Allergy, Asthma & Immunology (ACAAI) and the Society for Academic Emergency Medicine (SAEM).

Recent advances in the management of hereditary angioedema

Hereditary angioedema (HAE) is a rare genetic condition that manifests as painful and potentially life-threatening episodic attacks of cutaneous and submucosal swelling. It results from functional deficiency of C1 inhibitor (C1 INH), which is a regulator of the complement, fibrinolytic, kinin (contact), and coagulation systems. In patients with HAE, the low plasma concentration of functional C1 INH leads to overactivation of the kinin cascade and local release of bradykinin. Bradykinin is responsible for the pain, vascular permeability changes, and edema associated with HAE. Until recently, therapeutic options for HAE have been very limited. Many new therapies have emerged, however, such as C1 INH replacement drugs and medications aimed at components of the contact system (eg, plasma kallikrein inhibitor and bradykinin B2 receptor antagonist). The authors review current and novel treatments for patients with HAE.

On-demand therapy for hereditary angioedema

Consensus guidelines on hereditary angioedema (HAE) recommend that all patients have access to on-demand treatment of acute attacks. A recent patientcentric guideline recommended that at least 2 on-demand therapies be available because patients often have heterogeneous responses to different medications. Self-administration of therapeutic agents, or administration under supervision by a health care provider in the home setting, is the preferred treatment approach. Future studies are needed to show the benefits of acute on-demand therapies at improving quality of life and reducing morbidity and mortality in patients with HAE.

Anaesthesia Management of a Patient with Hereditary Angioedema with Prophylactic Administration of C1 Esterase Inhibitor: Case report and literature review

Hereditary angioedema (HAE) is a rare disorder caused by a deficiency of C1 esterase inhibitor. Minor trauma and emotional stress are the most common initiating events leading to contact system activation and excessive uncontrolled bradykinin release. This manifests as angioedema, a vascular reaction of the deeper layers of the skin and mucous membranes, with vasodilatation and increased permeability resulting in tissue swelling. Severe angioedema can occur in the perioperative period, leading to fatal airway obstruction. We describe the anaesthetic management of a child with HAE for dental rehabilitation and provide an review of the relevant literature.

Hereditary angioedema caused by c1-esterase inhibitor deficiency: a literature-based analysis and clinical commentary on prophylaxis treatment strategies

Hereditary angioedema (HAE) caused by C1-esterase inhibitor deficiency is an autosomal-dominant disease resulting from a mutation in the C1-inhibitor gene. HAE is characterized by recurrent attacks of intense, massive, localized subcutaneous edema involving the extremities, genitalia, face, or trunk, or submucosal edema of upper airway or bowels. These symptoms may be disabling, have a dramatic impact on quality of life, and can be life-threatening when affecting the upper airways. Because the manifestations and severity of HAE are highly variable and unpredictable, patients need individualized care to reduce the burden of HAE on daily life. Although effective therapy for the treatment of HAE attacks has been available in many countries for more than 30 years, until recently, there were no agents approved in the United States to treat HAE acutely. Therefore, prophylactic therapy is an integral part of HAE treatment in the United States and for selected patients worldwide. Routine long-term prophylaxis with either attenuated androgens or C1-esterase inhibitor has been shown to reduce the frequency and severity of HAE attacks. Therapy with attenuated androgens, a mainstay of treatment in the past, has been marked by concern about potential adverse effects. C1-esterase inhibitor works directly on the complement and contact plasma cascades to reduce bradykinin release, which is the primary pathologic mechanism in HAE. Different approaches to long-term prophylactic therapy can be used to successfully manage HAE when tailored to meet the needs of the individual patient.

Emerging concepts in the diagnosis and treatment of patients with undifferentiated angioedema

Angioedema is a sudden, transient swelling of well-demarcated areas of the dermis, subcutaneous tissue, mucosa, and submucosal tissues that can occur with or without urticaria. Up to 25% of people in the US will experience an episode of urticaria or angioedema during their lifetime, and many will present to the emergency department with an acute attack. Most cases of angioedema are attributable to the vasoactive mediators histamine and bradykinin. Histamine-mediated (allergic) angioedema occurs through a type I hypersensitivity reaction, whereas bradykinin-mediated (non-allergic) angioedema is iatrogenic or hereditary in origin.Although their clinical presentations bear similarities, the treatment algorithm for histamine-mediated angioedema differs significantly from that for bradykinin-mediated angioedema. Corticosteroids, and epinephrine are effective in the management of histamine-mediated angioedema but are ineffective in the management of bradykinin-mediated angioedema. Recent advancements in the understanding of angioedema have yielded pharmacologic treatment options for hereditary angioedema, a rare hereditary form of bradykinin-mediated angioedema. These novel therapies include a kallikrein inhibitor (ecallantide) and a bradykinin β2 receptor antagonist (icatibant). The physician's ability to distinguish between these types of angioedema is critical in optimizing outcomes in the acute care setting with appropriate treatment. This article reviews the pathophysiologic mechanisms, clinical presentations, and diagnostic laboratory evaluation of angioedema, along with acute management strategies for attacks.

New treatment options for acute edema attacks caused by hereditary angioedema

PURPOSE

New treatment options for acute edema attacks caused by hereditary angioedema (HAE) are reviewed.

SUMMARY

HAE is characterized by mutations in the C1 inhibitor gene leading to either a reduced expression of C1 inhibitor in the plasma or expression of a functionally impaired C1 inhibitor. HAE is classified into two major types based on the cause of the C1 inhibitor deficiency. Type I HAE is defined by a reduced expression of C1 inhibitor in the plasma, whereas type II HAE is characterized by the expression of a dysfunctional C1 inhibitor protein. Clinical data were reviewed for C1 inhibitor, ecallantide, and icatibant in the treatment of acute edema attacks caused by HAE. C1 inhibitor leads to a faster onset of edema relief and is effective in decreasing the duration of edema. Dosing strategies include fixed dosing and weight-based dosing. Optimal dosing strategies have not been established, but fixed dosing (500-1000 units) or 20 units/kg has been effective in clinical trials and reports. No comparative trials suggest that one strategy is superior to another; however, the approved labeling for acute treatment is based on weight. Ecallantide is also efficacious for treating acute episodes; however, the available evidence is limited to a single published trial. Icatibant has shown variable effects in two trials with placebo and active controls.

CONCLUSION

In patients with HAE, most edema episodes only involve the skin and gastrointestinal tract, though airway obstruction caused by laryngeal angioedema is the most common cause of death. I.V. C1 inhibitor should be considered first-line treatment for acute edema attacks because of its fast onset of action and effectiveness, though it is not clear whether fixed or weight-based dosing is preferred. Ecallantide can be considered as a second-line treatment option.

Diagnosis and management of hereditary angioedema: an emergency medicine perspective

BACKGROUND

Hereditary angioedema (HAE) is a rare and often debilitating condition associated with substantial morbidity and mortality in the absence of appropriate intervention. An underlying deficiency in functional C1-inhibitor (C1-INH) protein induces a vulnerability to unchecked activation of the complement, contact, and coagulation/fibrinolytic systems. The clinical consequence is a pattern of recurring attacks of non-pitting, non-pruritic edema, the urgency of which varies by the affected site. Laryngeal edema can escalate rapidly to asphyxiation, and severe cases of abdominal swelling can lead to hypovolemic shock.

OBJECTIVES

This report reviews the emergency diagnosis and treatment of hereditary angioedema and the impact of recently introduced treatments on treatment in the United States.

DISCUSSION

Until recently, emergency physicians in the United States were hindered by the lack of rapidly effective treatment options for HAE attacks. In this article, general clinical and laboratory diagnostic procedures are reviewed against the backdrop of two case studies: one patient presenting with a known history of HAE and one with previously undiagnosed HAE. In many countries outside the United States, plasma-derived C1-INH concentrate has for decades been the first-line treatment for acute attacks. The end of 2009 ushered in a new era in the pharmacologic management of HAE attacks in the United States with the approval of two new treatment options for acute treatment: a plasma-derived C1-INH concentrate and a kallikrein inhibitor.

CONCLUSION

With access to targeted and effective treatments, emergency physicians are now better equipped for successful and rapid intervention in urgent HAE cases.

Ecallantide for the treatment of hereditary angiodema in adults

Hereditary angioedema (HAE) is a clinical disorder characterized by a deficiency of C1 esterase inhibitor (C1-INH). HAE has traditionally been divided into two subtypes. Unique among the inherited deficiencies of the complement system, HAE Types I and II are inherited as an autosomal dominant disorder. The generation of an HAE attack is caused by the depletion and/or consumption of C1-inhibitor manifested as subcutaneous or submucosal edema of the upper airway, face, extremities, or gastrointestinal tract mediated by bradykinin. Attacks can be severe and potentially life-threatening, particularly with laryngeal involvement and treatment of acute attacks in the United States has been severely limited. In December 2009 the FDA approved ecallantide for the treatment of acute HAE attacks. Ecallantide is a small recombinant protein acting as a potent, specific and reversible inhibitor of plasma kallikrein which binds to plasma kallikrein blocking its binding site, directly inhibiting the conversion of high molecular weight kininogen to bradykinin. Administered subcutaneously, ecallantide was demonstrated in two clinical trials, EDEMA3 and EDEMA4, to decrease the length and severity of acute HAE attacks. Although there is a small risk for anaphylaxis, which limits home administration, ecallantide is a novel, safe, effective and alternative treatment for acute HAE attacks.

Population pharmacokinetics of plasma-derived C1 esterase inhibitor concentrate used to treat acute hereditary angioedema attacks

BACKGROUND

C1 esterase inhibitor (C1-INH) replacement is recommended as a first-line therapy for acute edema attacks in hereditary angioedema (HAE). Only limited pharmacokinetic analyses of the administered C1-INH in plasma are available.

OBJECTIVE

To investigate retrospectively the population pharmacokinetics of a plasma-derived C1-INH (pC1-INH) concentrate used to treat acute HAE attacks in a randomized, placebo-controlled phase 2/3 study in patients with HAE.

METHODS

Acute abdominal and facial attacks were treated with either a pC1-INH concentrate (Berinert) at single intravenous doses of 10 or 20 U/kg body weight or placebo. Plasma sampling was conducted 0, 1, and 4 hours after dosing. A nonlinear retrospective population pharmacokinetic model was obtained using the assumption of a 1-compartment model.

RESULTS

The final population pharmacokinetic model was based on data from 97 patients treated with 10 or 20 U/kg of pC1-INH concentrate. The estimated mean half-life was 32.7 hours (90% confidence interval, 16.6-48.8 hours), and the estimated mean clearance was 0.92 mL/kg/h (90% confidence interval, 0.50-1.33 mL/kg/h).

CONCLUSIONS

The half-life of the same pC1-INH concentrate reported in a previous study was confirmed by this retrospective population pharmacokinetic analysis in patients treated for acute HAE attacks. In contrast to other treatment options with shorter half-lives, the long half-life of pC1-INH concentrate may provide an extended period of protection, even after the symptoms of an attack have subsided.

Ecallantide for the treatment of acute attacks in hereditary angioedema

BACKGROUND

Hereditary angioedema is a rare genetic disorder characterized by acute, intermittent, and potentially life-threatening attacks of edema of the skin and mucosa. We evaluated ecallantide, a newly developed recombinant plasma kallikrein inhibitor, for the treatment of acute attacks of angioedema.

METHODS

In this double-blind, placebo-controlled trial, patients with hereditary angioedema presenting with an acute attack were randomly assigned, in a 1:1 ratio, to receive subcutaneous ecallantide, at a dose of 30 mg, or placebo. Two measures of patient-reported outcomes were used to assess the response: treatment outcome scores, which range from +100 (designated in the protocol as significant improvement in symptoms) to -100 (significant worsening of symptoms), and the change from baseline in the mean symptom complex severity score, which range from +2 (representing a change from mild symptoms at baseline to severe symptoms after) to -3 (representing a change from severe symptoms at baseline to no symptoms after). The primary end point was the treatment outcome score 4 hours after study-drug administration. Secondary end points included the change from baseline in the mean symptom complex severity score at 4 hours and the time to significant improvement.

RESULTS

A total of 71 of the 72 patients completed the trial. The median treatment outcome score at 4 hours was 50.0 in the ecallantide group and 0.0 in the placebo group (interquartile range [IQR], 0.0 to 100.0 in both groups; P=0.004). The median change in the mean symptom complex severity score at 4 hours was -1.00 (IQR, -1.50 to 0.00) with ecallantide, versus -0.50 (IQR, -1.00 to 0.00) with placebo (P=0.01). The estimated time to significant improvement was 165 minutes with ecallantide versus more than 240 minutes with placebo (P=0.14). There were no deaths, treatment-related serious adverse events, or withdrawals owing to adverse events.

CONCLUSIONS

Four hours after administration of ecallantide or placebo for acute attacks of angioedema in patients with hereditary angioedema, patient-reported treatment outcome scores and mean symptom complex severity scores were significantly better with ecallantide than with placebo. (Funded by Dyax; ClinicalTrials.gov number, NCT00262080.)

EDEMA4: a phase 3, double-blind study of subcutaneous ecallantide treatment for acute attacks of hereditary angioedema

BACKGROUND

Hereditary angioedema (HAE) is a genetic disorder resulting from low levels of C1-inhibitor activity that manifests as acute attacks of variable and sometimes life-threatening edema. Ecallantide is a novel potent inhibitor of human plasma kallikrein, a key mediator of the excessive formation of bradykinin associated with the signs and symptoms of an HAE attack.

OBJECTIVE

To evaluate the efficacy and safety of ecallantide in the treatment of acute HAE attacks.

METHODS

In this double-blind, placebo-controlled study, patients with a moderate to severe HAE attack were randomized 1:1 to receive 30 mg of subcutaneous ecallantide or placebo. The primary efficacy end point was change from baseline in mean symptom complex severity score 4 hours after dosing. Additional end points included treatment outcome score 4 hours after dosing and maintenance of significant overall improvement through 24 hours.

RESULTS

Ninety-six patients were enrolled. Mean (SD) change from baseline in mean symptom complex severity score 4 hours after dosing was significantly greater with ecallantide use (-0.8 [0.6]) compared with placebo use (-0.4 [0.8]) (P = .01 comparing distributions). Ecallantide therapy was also associated with a significantly larger mean (SD) treatment outcome score 4 hours after dosing vs placebo use (ecallantide: 53.4 [49.7]; placebo: 8.1 [63.2]; P = .003 comparing distributions). The benefit of ecallantide was apparent within 2 hours after dosing and was maintained through 24 hours after dosing. The safety profile was similar between the treatment groups.

CONCLUSION

Ecallantide appears to be an effective and safe treatment for acute attacks of HAE.

Upper airway considerations in hereditary angioedema

PURPOSE OF REVIEW

The purpose of the present review is to outline the clinical aspects and management of the upper airway involvement in the patients suffering from hereditary angioedema.

RECENT FINDINGS

Molecular mechanisms of hereditary angioedema reviewed in the literature conclude that it is an autosomal dominant disorder, characterized by the deficiency of C1 inhibitor due to mutations of its gene (SERPING). Hereditary angioedema manifests as episodes of localized swelling in any site of the body from skin, gastrointestinal tract to the upper airway, where it is severe and life-threatening. The age of onset, frequency of attacks and the factors triggering upper airway swelling in hereditary angioedema are variable among different patients. Acute laryngeal edema should be managed in emergency with monitoring of airway patency. To avoid airway obstruction, therapy should begin early either with current treatment (C1 inhibitor concentrate) or with new drugs developed recently. In patients with recurrent upper airway swelling attacks, long-term prophylaxis is recommended.

CONCLUSION

The use of old and new treatment in acute attacks as well as in prophylaxis (long and short-term) has changed the outcome of patients with hereditary angioedema who present upper airway swelling.

Hereditary angioedema: New therapeutic options for a potentially deadly disorder

Although the biochemistry of hereditary angioedema (HAE) is fairly well understood today, the lag in diagnosis of a decade or more suggests that clinicians have low awareness of this disease. This lag in diagnosis and hence treatment certainly stems from the rarity and complexity of the presentation which can be easily mistaken for allergic and non-allergic reactions alike. The symptoms of the disease include acute swelling of any or multiple parts of the body. The attacks may be frequent or rare, and they may vary substantially in severity, causing stomach discomfort or periorbital swelling in mild cases and hypovolemic shock due to abdominal fluid shift or asphyxiation in the most severe cases. Given that these patients are at significant risk for poor quality of life and death, greater awareness of this disease is needed to ensure that newly available, effective medications are used in these patients. These new medications represent significant advances in HAE therapy because they are targeted at the plasma cascades implicated in the pathophysiology of this disease. The clinical presentation of HAE, overlapping symptoms with other angioedemas, and available therapies are reviewed.

Hereditary angioedema: treatment, management, and precautions in patients presenting for dental care

Hereditary angioedema (HAE) is a nonhistamine-mediated process causing edema of the tissues of the upper airway, dermis, and subcutaneous tissue. As such it does not respond well to epinephrine, antihistamines, or glucocorticoids. Instead it is treated with attenuated androgenic hormones, episolone aminocaproic acid (EACA), or tranexamic acid, C1 esterase inhibitor, and fresh-frozen plasma. Medical or surgical management of the airway may be necessary in an acute situation. Minor trauma, such as that associated with dental procedures and psychologic stress, may precipitate an attack; however, swelling may not manifest itself for 12-48 hours after a procedure. Symptoms of angioedema may be exacerbated in these patients if they are given an angiotensin-converting enzyme inhibitor. This paper reviews this entity and presents 2 patients who presented for acute care with dental/oral surgical complaints.

Ecallantide: its pharmacology, pharmacokinetics, clinical efficacy and tolerability

Ecallantide (Kalbitor, Dyax Corporation) is a highly specific recombinant plasma kallikrein inhibitor developed for treatment of hereditary angioedema (HAE). Advantages of this agent over plasma-derived treatments are that it poses no risk of viral contamination, is highly selective, has a quick onset of action and can be administered subcutaneously. In clinical trials, ecallantide appears to be a safe and effective drug useful for the treatment of HAE patients suffering from an acute attack. Ecallantide was found to be superior compared with placebo in relieving symptoms, decreasing the severity of attacks and shortening the duration of attacks. The primary safety concern appears to be related to hypersensitivity reactions. Phase IV postmarketing surveillance studies to monitor the incidence of these reactions will be implemented by the company now that the drug has been US FDA approved.

Progress in phage display: evolution of the technique and its application

Phage display, the presentation of (poly)peptides as fusions to capsid proteins on the surface of bacterial viruses, celebrates its 25th birthday in 2010. The technique, coupled with in vitro selection, enables rapid identification and optimization of proteins based on their structural or functional properties. In the last two decades, it has advanced tremendously and has become widely accepted by the scientific community. This by no means exhaustive review aims to inform the reader of the key modifications in phage display. Novel display formats, innovative library designs and screening strategies are discussed. I will also briefly review some recent uses of the technology to illustrate its incredible versatility.

Clinical review of hereditary angioedema: diagnosis and management

Hereditary angioedema (HAE) is caused by a deficiency in C1 esterase inhibitor and is characterized by sudden attacks of edema associated with discomfort and pain. The disease places patients at risk for disability and death if left untreated. Symptom severity and frequency can be extremely variable even among affected members of the same family. Attacks are not associated with inflammation or allergy, with most occurring secondary to trauma or stress. Swelling can affect any part of the body or multiple sites at once. Commonly affected areas include the extremities, genitalia, trunk, gastrointestinal tract, face, and larynx. Swelling typically worsens over 24 to 36 hours and resolves within 48 hours in less severe cases. Attacks result in 15,000 to 30,000 emergency department visits each year. Many of these emergency cases will undergo unnecessary surgeries or medical procedures due to misdiagnosis. The hallmarks of HAE--recurrent episodes of swelling without urticaria, a family history of HAE, first attack in childhood, and worsening at puberty--can be identified by a thorough family history, and the diagnosis can be confirmed by laboratory studies. Nevertheless, diagnosis may be delayed by 2 decades. We review available therapies and clinical characteristics that will both help clinicians diagnose HAE and distinguish among emergencies and nonemergency cases.

Therapeutic potential of complement modulation

The complement system is an essential component of innate immunity that has been more recently recognized as an unexpected player in various pathological states. These include age-related macular degeneration, atypical haemolytic uraemic syndrome, allergy, foetal loss, and axonal and myelin degradation after trauma. Its importance has also been recognized in physiological processes including haematopoietic stem cell homing to the bone marrow, liver regeneration and modulation of adaptive immune responses. Although the complement system has long been known to be involved in autoimmune and inflammatory diseases, few agents that target the complement system are currently approved for clinical use. However, renewed interest in modulating this system in various pathological conditions has emerged, and several agents are now in development.

Synthesis of chemically modified bioactive peptides: recent advances, challenges and developments for medicinal chemistry

Although not complying with Lipinski’s rule, peptides are to an increasing extent being developed into new active pharmaceutical ingredients. This is mainly due to novel application routes, formulations and chemical modifications, which confer on the peptides improved uptake and increased metabolic stability. A brief survey of currently approved peptide drugs and the present scope of the application of peptides as drugs is provided. Cyclic peptides are emerging as an interesting class of peptides with conformational rigidity and homogeneity, high receptor affinity and selectivity, increased metabolic stability and – in special cases – even oral availability. Challenges and new methodology for the synthesis of cyclic peptides are outlined and an overview of approaches toward the design of peptide conformation and peptide modification by nonproteinogenic building blocks is given.