Angioedema. Pathogenesis, differential diagnosis, and treatment

Intestinal Angioedema: A Mimic of an Acute Abdomen

Visceral angioedema presents with features mimicking an acute abdomen, causing a great challenge in the diagnosis of the disease thus delaying the treatment. A high degree of radiological suspicion and clinical correlation will help in identifying this less-known entity, avoiding unnecessary surgery. CT scanning is the preferred investigation, but concomitant ultrasonography improves the diagnostic efficacy of CT scanning.

A Comprehensive Review of Bradykinin-Induced Angioedema Versus Histamine-Induced Angioedema in the Emergency Department

Angioedema (AE) is a condition that is frequently encountered in the emergency department (ED). It is a rare condition with localized, asymmetrical swelling of the skin and/or mucosa that is frequently nonpruritic and primarily affects locations with loose connective tissue. Physicians must have a thorough understanding of this condition since it can cause fatal airway compromise, which might be the presenting symptom. Histamine-mediated AE is the most common type of AE seen in EDs. However, ED physicians must be on the lookout for the less common bradykinin-mediated types of AE as these do not respond to the same therapy as histamine-mediated AE. Hospitals may lack specialized drugs or protocols, and many ED staff may be unable to identify or treat bradykinin-mediated AE. It is crucial to understand the pathophysiology of the various kinds of AE in order to optimize treatment. The goal of this review paper is to provide an overview of the pathophysiology, clinical manifestations, and treatment options for bradykinin and histamine-induced AE in the ED.

Imaging Review of Angiotensin-Converting Enzyme Inhibitor-Induced Angioedema of the Head and Neck

Angiotensin-converting enzyme inhibitors (ACE-i) are commonly used medications to treat hypertension and congestive heart failure. Angioedema is a well-established side effect of ACE-i and most commonly manifests as swelling of the mucosal and extra-mucosal soft tissues in the head and neck. CT with contrast is generally used to evaluate for airway compromise and to exclude other etiologies of edema. Herein we present five cases that illustrate the radiological findings specific to ACE-i-induced angioedema on enhanced CT scans.

Extending our understanding of exenatide: a rare case of angio-oedema

Exenatide is a subcutaneous injectable glucagon-like peptide 1 receptor agonist that has been approved by the Federal Drug Administration for the treatment of type 2 diabetes mellitus. While side effects such as nausea, vomiting and local hypersensitivity reactions are more commonly described, angio-oedema has never been previously reported in the literature. We present the case of a 67-year-old woman who presented to the emergency department with acute-onset tongue swelling, difficulty breathing, dizziness and diffuse itching which began shortly after receiving her first dose of intramuscular extended release (ER) exenatide. This case aims to raise awareness of the potential adverse effect of angio-oedema secondary to exenatide ER and serves as a reminder to clinicians to discuss possible adverse effects of medications and early recognition of symptoms which would prompt further medical attention.

Ezetimibe: An Unusual Suspect in Angioedema

We describe a case of new onset angioedema likely due to Ezetimibe therapy in an elderly patient with a prior history of drug-induced bradykinin reactions who had been on the medication for multiple years. This is the second reported incidence of Ezetimibe-associated angioedema in literature. A 90-year-old African American female presented with angioedema of the face and oral mucosa with associated difficulty speaking developing hours after taking Ezetimibe 10 mg PO. She denied adding any new or unusual foods to her diet. A thorough clinical history determined Ezetimibe was the likely culprit. Ezetimibe was immediately discontinued. The swelling subsided after administration of methylprednisolone 125 mg, epinephrine 1 mg/mL, injection 0.3 mL, diphenhydramine 25 mg, and famotidine 20 mg BID within 48 hours. The patient's C1 esterase inhibitor level was measured to be within normal limits. Food panel allergy testing showed very low or undetectable IgE levels in all categories. Based on the limited reports in literature and our current case, we conclude that there is a likely association of angioedema with Ezetimibe. The mechanism, however, is unknown since it is not related to bradykinin or mast cell-mediated activation. Clinicians should advise patients taking Ezetimibe to report any swelling of the lips, face, and tongue and to immediately discontinue its use if these signs are present.

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.

Idiopathic Intestinal Angioedema: A Diagnostic Dilemma

Angioedema is an allergic reaction that usually involves the face and pharynx. Intestinal angioedema is a rare subtype that is typically linked to the use of angiotensin-converting enzymes inhibitors (ACEIs). Intestinal angioedema is challenging to diagnose, as it can mimic gastroenteritis or other inflammatory bowel conditions. Herein, we present a 34-year-old female who presented with recurrent episodes of abdominal pain. She underwent extensive workup for her abdominal pain and rash, and all was unrevealing except for high Immunoglobulin E (Ig E). Multiple imaging came back negative for any pathology. The allergy and immunology team evaluated the patient, and they believed her symptoms are likely caused by isolated intestinal angioedema with a histamine-related rash. She was started on high doses of antihistamines; her symptoms partially improved. Subsequently, she was started on a trial of omalizumab, which resulted in complete resolution of her symptoms. In conclusion, intestinal angioedema is a rare disease that should be suspected in cases of recurrent abdominal pain with negative workup, especially if the patient is taking ACEIs. Few cases were reported in the literature for patients on ACEI. In our case, the diagnosis was a challenge, as the patient was never on ACEI.

Hereditary Angio-Oedema for Dermatologists

Among angio-oedema patients, hereditary angio-oedema (HAE) should not be overlooked. Besides skin swellings, these patients might have very painful abdominal attacks and potentially life-threatening angio-oedema of the upper airway. They will not respond to traditional anti-allergic therapy with antihistamines, corticosteroids, and adrenaline, and instead need specific drugs targeting the kallikrein-kinin pathway. Classically, patients with HAE have a quantitative or qualitative deficiency of the C1 inhibitor (C1INH) due to different mutations in SERPING1, although a new subtype with normal C1INH has been recognised more recently. This latter variant is diagnosed based on clinical features, family history, or molecular genetic testing for mutations in F12, ANGPT1,or PLG.The diagnosis of HAE is often delayed due to a general unfamiliarity with this orphan disease. However, undiagnosed patients are at an increased risk of unnecessary surgical interventions or life-threatening laryngeal swellings. Within the last decade, new and effective therapies have been developed and launched for acute and prophylactic therapy. Even more drugs are under evaluation in clinical trials. It is therefore of utmost importance that patients with HAE are diagnosed as soon as possible and offered relevant therapy with orphan drugs to reduce morbidity, prevent mortality, and improve quality of life.

[Angioedema: differential diagnosis]

Angioedema (AO) is a clinical syndrome defined by a local swelling of the deep dermis or subcutaneous/submucosal tissues. AO is of rapid installation, non-pruritic, always circumscribed and transitory without any sequellae. A swelling not fulfilling these characteristics is not an AO. Characterization of the bradykinic or histaminic mechanism should not be started until it is firmly established that the patient has an AO. Among differential diagnosis of AO, two clinical situations can be particularly misleading: generalized edema with flare and remission or with a subjective or objective localized predominance; permanent localized edema but with fluctuation during time. Diagnosis of AO should be questioned if the evolution is unusual or if there is a resistance to the treatment. Hereditary AO are rare diseases whereas histaminic AO are much more frequent (beware of overdiagnosis of a rare disease). Even in patients with a known and real AO, a differential diagnosis should be evoked when a new clinical manifestation is atypical or is treatment resistant.

Examination of genetic variants involved in generation and biodisposition of kinins in patients with angioedema

Background

Angioedema (AE) is idiopathic in the majority of cases. We studied patients with AE for genetic variants of proteins involved with bradykinin generation and biodisposition.

Methods

One hundred sixty one patients with AE were recruited at a university hospital clinic. Patients were categorized according to the proposed pathogenesis of AE: low C1 inhibitor (C1-INH) and C4 levels, autoimmune disease, cancer, angiotensin-converting enzyme (ACE) inhibitor-induced, nonsteroidal antiinflammatory drug (NSAID)-induced, or idiopathic. In addition, each patient had a blood sample analyzed for a complement profile and enzymes (C1-INH and C4). Fifty-two of the patients were tested for genetic variants in factor XII, plasminogen-activator inhibitor-1 (PAI-1), ACE, and aminopeptidase P (APP).

Results

The cause of angioedema was identified in 59/161 (37%) of the cases: 3 (2%) patients had a low plasma C1-INH and C4; 20 (12%) were ACE inhibitor-induced; 12 (7%) were associated with autoimmune disorders; 7 (4%) were associated with malignancy; and 17 (11%) were associated with NSAIDs. In the remaining 102 (63%) patients the cause of angioedema was idiopathic. Of 52 patients with genetic analysis, 13 (25%) had a genetic variant in APP, 10 (19%) in ACE, 13 (25%) in PAI-1, and 0 in Factor XII.

Conclusions

In addition to related diseases and medications causing AE, certain genetic variants encoding proteins involved in bradykinin generation and/or catabolism pathways may be involved in the pathogenesis of AE.

Chronic idiopathic angioedema: a single center experience

OBJECTIVE

Chronic idiopathic angioedema (CIA) is defined as three or more episodes of angioedema in a period of > 6 months without a clear etiology. In the study, we tried to explore clinical and laboratory characteristics of patients with CIA unaccompanied by urticaria.

METHODS

We retrospectively reviewed clinical and laboratory characteristics of 1238 patients with chronic urticaria and/or angioedema referred to our allergy clinic.

RESULTS

Eight hundred and forty-one (67.9%) subjects had chronic urticaria without angioedema (CU Group), 323 (26.1%) had both urticaria and angioedema (CU + CA group), and 74 (5.9%) had chronic angioedema without urticaria (CA). In 29 (39.2%) cases of CA, no etiologic factor of angioedema was discovered, thus the patients were defined as having chronic idiopathic angioedema (CIA Group). Twenty-two (75.8%) subjects had antihistamine-responsive CIA and seven (24.1%) had antihistamine-unresponsive CIA. There were no statistically significant differences in clinical (except of urticarial eruptions) and laboratory characteristics between CU, CA + CU, and CIA groups. Antihistamine responsive and antihistamine-unresponsive CIA groups had no distinguishable clinical or laboratory features.

CONCLUSIONS

We suppose that CIA, at least its antihistamine-responsive form, represents a rare form of chronic spontaneous urticaria. The reasons why in CIA there are no other clinical signs of mast cell/basophil activation, such as pruritus, urticarial, and dermatographism, are largely unknown and have to be elucidated in future studies.

Risk factors associated with severe and recurrent angioedema: an epidemic linked to ACE-inhibitors

OBJECTIVES/HYPOTHESIS

To evaluate the etiology and risk factors for severe manifestation and recurrent episodes of angioedema; to evaluate efficacy of short-term and long-term management strategies for angioedema among a high-risk population.

STUDY DESIGN

Institutional review board-approved retrospective review of a large, urban population.

METHODS

Data from 875 adult patients treated from January 2008 to December 2013 with the diagnosis of angioedema were obtained using the Clinical Looking Glass utility and review of medical records. Demographic and clinicopathologic risk factors were recorded. The major outcomes evaluated were hospital admission, need for airway intervention, and recurrent episodes of angioedema following the first presentation. Initial treatment strategy and follow-up recommendations were also recorded.

RESULTS

The most common cause of angioedema was angiotensin converting enzyme inhibitor (ACEi)-induced (496 [56.6%]). Significant risk factors for severe cases of angioedema included older age, Hispanic race, ACEi-induced angioedema type, American Society of Anesthesiologists class III or above, coexistent cardiopulmonary disease, and a positive smoking history. A total of 17.2% of patients experienced recurrent attacks of angioedema; of those patients, 25.9% were still taking an ACEi at subsequent presentation. Risk factors for recurrent episodes included older age, idiopathic angioedema type, and coexistent cardiopulmonary disease. Only 54.1% of patients who experienced ACEi-induced angioedema had electronic medical record documentation of these allergies.

CONCLUSIONS

Knowledge of risk factors for severe and recurrent episodes of angioedema and improved education for both healthcare providers and patients, specifically related to ACEi use and allergy documentation, may significantly decrease the burden and morbidity of angioedema among high risk populations.

LEVEL OF EVIDENCE

2b.

Radiologic manifestations of angioedema

OBJECTIVES

The purpose of this pictorial review is to present imaging findings of angioedema involving the various organs.

CONCLUSION

The role of imaging for patients with angioedema includes the evaluation of the upper airway for obstruction and the exclusion of other possible aetiologies, such as neoplastic or infectious processes. Glossomegaly is a common finding of head and neck angioedema. Angioedema may involve organ systems beyond the superficial regions and the head and neck including the gastrointestinal and genitourinary tracts. Angioedema of the visceral organs is often accompanied by adjacent fluid, and it is commonly diffuse or concentric but can also be multifocal and asymmetric.

TEACHING POINTS

• The evaluation of the upper airway obstruction is important for head and neck angioedema. • Glossomegaly with decreased attenuation is common in head and neck angioedema. • Angioedema of the visceral organs can be multifocal and asymmetric. • Angioedema of the visceral organs is often accompanied by adjacent fluid. • It is important to include clinical and laboratory findings for the diagnosis of angioedema.

Angioedema with normal laboratory values: the next step

When faced with a patient with recurrent swelling, a thorough laboratory evaluation to determine the underlying etiology ensues. When the laboratory work-up is unrevealing, health care practitioners are frequently left in a quandary. This review will attempt to provide up-to-date information on how to approach the diagnosis and management of angioedema in a patient with normal laboratory values. The subtypes that will be reviewed in detail include: hereditary angioedema with normal C1 inhibitor (HAE with normal C1INH), drug-induced angioedema, and idiopathic angioedema. We present literature to aid the physician in the diagnosis and treatment of these disorders.

Angioedema--assessment and treatment

BACKGROUND

Angioedema has numerous hereditary, acquired and iatrogenic causes. A number of studies show that angioedema is inadequately assessed and treated during its acute phase as well as in the follow-up period. We present an algorithm for the assessment and treatment of patients with angioedema. KNOWLEDGE BASE: The article is based on a literature search in PubMed, a review of bibliographies and the authors' clinical experience and research.

RESULTS

The majority of angioedema patients have accompanying urticaria. Pathophysiologically, angioedemas are divided into histaminergic and non-histaminergic forms. In a large group of patients no positive trigger is identified. On assessment in hospital the most frequently identified cause is drug intake, normally angiotensin-converting-enzyme inhibitors and NSAIDs , while allergic/pseudoallergic and idiopathic reactions are more commonly seen in general practice. There are a number of rare causes of angioedema, all of which are important to keep in mind. The acute and prophylactic treatment will depend on the subtype of angioedema and is best provided through cross-disciplinary collaboration.

INTERPRETATION

Angioedema is a potentially life-threatening condition and should be assessed and treated systematically. It is important to remember that angioedema is either histaminergic or non-histaminergic, as the treatment of the two types is different.

Urticaria and angioedema

Urticaria and angioedema are common disorders that can severely impair the quality of a patient's life and can be extremely difficult to treat. Symptoms can persist for years to decades. The causes of urticaria and angioedema are varied and may be immunologic, nonimmunologic, or idiopathic. This article reviews the literature and provides primary care physicians with up-to-date information of the epidemiology, basic pathophysiology, diagnosis, and management of this common and often debilitating condition. Additionally, clinical manifestations of acute and chronic urticaria, hereditary and acquired angioedema, as well as the physical urticarias will be discussed.

A case of angioedema due to acquired C1 esterase inhibitor deficiency masquerading as suspected peritonitis: a case report

Angioedema due to acquired C1 esterase deficiency is a rare condition and a non-inflammatory disease characterized by episodes of edema of the mucosa of the upper airway or gastrointestinal tract. The purpose of this case report is to heighten awareness among emergency physicians of a peritonitis-like condition that can develop into angioedema due to acquired C1 esterase inhibitor deficiency, and thereby help to prevent false diagnosis resulting in unnecessary surgical intervention. We report the case of a 21-year-old man who presented to the Emergency Department (ED) with abdominal pain. He was later diagnosed with angioedema of the gastrointestinal tract due to acquired C1 esterase deficiency that was initially suspected as peritonitis. Careful evaluation of the acute abdomen in acquired C1 esterase deficiency is very important in the ED to distinguish between medical and surgical causes of an acute abdomen.

Acute urticaria and angioedema: diagnostic and treatment considerations

Urticaria is defined as wheals consisting of three features: (i) central swelling of various sizes, with or without surrounding erythema; (ii) pruritus or occasional burning sensations; and (iii) the skin returning to normal appearance, usually within 1-24 hours. Angioedema is defined as: (i) abrupt swelling of the lower dermis and subcutis; (ii) occasional pain instead of pruritus; (iii) commonly involving the mucous membranes; and (iv) skin returning to normal appearance, usually within 72 hours. Acute urticaria and angioedema is defined by its duration (<6 weeks) compared with chronic urticaria and angioedema. The most common causes are infections, medications, and foods. The best tools in the evaluation of these patients are a comprehensive history and physical examination. There are a variety of skin conditions that may mimic acute urticaria and angioedema and the various reaction patterns associated with different drugs. Oral antihistamines are first-line treatment. In the event of a life-threatening reaction involving urticaria with angioedema, epinephrine may be needed to stabilize the patient. This review focuses on the value of a comprehensive clinical evaluation at the onset of symptoms. It underscores the importance of coordination of care among physicians, and the development of an action plan for evidence-based investigations, diagnosis, and therapy.

Probable Amlodipine-Induced Angioedema

Objective:

To report a case of angioedema likely associated with amlodipine administration in a patient with a right thalamic hemorrhagic stroke.

Case Summary:

A 50-year-old female experienced angioedema during hospitalization for s right thalamic hemorrhagic stroke. She had no past history of angioedema and all of her medications were assessed for risk of angioedema. After careful evaluation, case reports linking calcium channel blockers (CCBs) and angioedema led to further examination of amlodipine as a cause. Amlodipine therapy had been initiated 24 hours prior to the development of angioedema, which then resolved 72 hours after discontinuation of the drug. In total, the patient experienced oropharyngeal swelling for 10 days.

Discussion:

In determining a cause for the patient's angioedema we eliminated genetic, allergic, physically induced, thyroid autoimmune disease-associated, and medication-induced causes. Three case reports describing 7 patients have linked the CCBs verapamil, diltiazem, and nifedipine with angioedema. The onset and resolution of symptoms in our patient were very similar to those seen in other case reports. Application of the Naranjo probability scale found a probable link between amlodipine and angioedema.

Conclusions:

Although few reports of CCB-induced angioedema exisi, to our knowledge, this is the first reported case to suggest a link between angioedema and amlodipine therapy. Clinicians should consider amlodipine as a potential cause of angioedema.

Acute pancreatitis due to hereditary angioedema

BACKGROUND

Hereditary angioedema (HAE) is an infrequent disorder characterized by abnormalities in the levels and/or function of complement C1 esterase inhibitor. Clinical manifestations of HAE are due to recurrent episodic swelling of the subcutaneous or submucosal tissue. When swelling involves the gastrointestinal mucosa, patients may present with nausea, vomiting, diarrhea, and severe abdominal pain. However, HAE is almost never suspected as a potential cause of acute pancreatitis.

OBJECTIVE

To describe a patient with HAE-associated pancreatitis requiring intensive medical care that responded favorably to conservative and supportive measures.

METHODS

Various tests were performed, including abdominal imaging, measurement of pancreatic enzymes levels, liver function tests, measurement of complement levels, and endoscopic retrograde cholangiopancreatography.

RESULTS

The results of these tests confirmed the diagnosis of HAE-associated acute pancreatitis. No other obvious origin, such as gallstones or alcohol use, was identified.

CONCLUSION

This case illustrates the need for a high clinical suspicion of acute pancreatitis when caring for patients with HAE who present with abdominal symptoms. There continues to be an urgent need for better and additional therapeutic options for HAE patients, including those to prevent and abort ongoing attacks.

Idiopathic Recurrent Angioedema

The treatment of idiopathic, chronic, recurrent angioedema with or without urticaria is difficult, both for patients and their physicians, because treatment often is only partially effective and is labor-intensive, expensive, and lengthy. New medications for urticaria and angioedema that currently are being tested clinically may prove effective.

Tongue swelling in the recovery room: a case report and discussion of postoperative angioedema

We present a case of potentially life-threatening postoperative swelling of the tongue and oropharynx that developed in the postanesthesia care unit in a patient taking lisinopril. The principal treatment of angioedema is the discontinuation of the precipitating agent and airway management. Patients with swelling limited to the face and oral cavity may only require monitoring. However, those with swelling in the floor of the mouth, tongue, and supraglottic or glottic areas should have their airway secured by tracheal intubation immediately. Early intubation in patients displaying these characteristics may decrease the incidence of emergent surgical airways. Angioedema is self-limiting, and the swelling usually resolves spontaneously in two to 3 days. Proper identification of angiotensin-converting enzyme inhibitor-associated angioedema requiring a timely airway intervention may reduce mortality, and recognition of its self-limiting course can prevent unnecessary tracheostomy.

Life-threatening angioedema in a patient with systemic lupus

We report a case of a young Chinese female who presented with life-threatening angioedema during an admission for flare-up of lupus disease. We discuss her investigations and management and include a review of the literature.

Solar angioedema: an uncommonly recognized condition?

Solar urticaria is a well defined although uncommon photosensitivity disorder, and is said to be the underlying cause of chronic urticaria in approximately 0.5% cases. In contrast, solar angioedema is seldom reported. We describe two patients with postulated solar angioedema, associated with clinical and/or phototest features of solar urticaria. Recognition of solar provocation of angioedema has important consequences for patient management.

Idiopatic angioedema treated with dapsone

The most commonly identified causes of angioedema are medications, allergens and physical agents, but most cases of angioedema are idiopathic. Treatment depends on identification of the causative agent and, especially when the mechanism is not identified, on the clinicians knowledge and experience with innovative therapeutic regimens.

CASE REPORT

A 48-year-old man presented with a 3-month history of recurrent severe episodes of angioedema affecting the lips, tongue and throat. A fiberoptic examination revealed laryngeal edema during some episodes. He did not report abdominal pain, nausea or vomiting. No precipitating factors were identified. The patient was not receiving angiotensin-converting enzyme inhibitors. For the previous 4 years, the patient had been receiving levothyroxine for autoimmune thyroiditis. There was no history of facial palsy or hereditary angioedema.

ALLERGY STUDY

Skin prick test with aeroallergens, food, latex, Anisakis and patch test to a standard series (true test) were negative. Laboratory investigations revealed normal complete blood count (CBC), erythrocyte sedimentation rate, urinalysis, blood biochemistry, serum protein electrophoresis and serum immunoglobulins. IgE concentration was 30 UI/ml. Antiperoxidase antibodies were positive (535 UI/ml). Antinuclear antibodies serum immune complexes and rheumatoid factor were negative. Complement study during acute and asymptomatic periods revealed normal values of C1 esterase inhibitor, C1q, C3, C4, functional activity of C1 inhibitor and CH50. No pathologic findings were observed in a lip biopsy. The patient was treated with sedating and nonsedating H1 antihistamines and corticosteroids (prednisone 30 mg/day for 3 months) with no clinical improvement and treatment with 50 mg of dapsone daily was started. Glucose 6 phosphate dehydrogenase deficiency had previously been ruled out. The patient improved and antihistamine and corticoid treatment was withdrawn 1 month after starting the dapsone regimen. No episodes of angioedema appeared during the subsequent year. No reductions in hematologic parameters or adverse events were detected. Dapsone may be an alternative drug in extreme cases of idiopathic angioedema in patients with poor response to conventional therapy.

Urticaria and angioedema: an overview

Persistent or frequent episodes of urticaria are difficult to evaluate and treat. The best test to identify most patients with a specific underlying cause (eg, physical trigger, allergen, systemic disease) likely is the taking of a careful and detailed history and performance of a physical examination by a specialist who is knowledgeable in urticarial disease. Further study of the pathogenesis and treatment of urticaria is crucial. Given the limited efficacy of presently approved antihistamine treatments and the significant side effects of steroids and cyclosporine, there is a pressing need to evaluate other anecdotally supported urticaria treatments in randomized, controlled trials.

Protease inhibitors in the treatment of hereditary angioedema

Deficiency of C1 Inhibitor leads to unopposed activation of complement, with localized, unpredictable, and sometimes life-threatening attacks of angioedema. Treatment with plasma-derived C1 Inhibitor rapidly aborts attacks, and may be lifesaving, but is expensive, requires use of a pooled blood product, may need to be repeated and may not be effective in autoantibody mediated angioedema. The antifibrinolytic agents aprotinin, tranexamic acid, and epsilon-aminocaproic acid are useful for prophylaxis and treatment of angioedema, likely by inhibiting plasmin. Specific drugs to replace the deficient C1 Inh have not been reported. The kallikrein inhibitor DX-88 (Dyax) has received orphan drug status in Europe and is undergoing clinical trial in Europe and the USA.