Optimal treatment of anaphylaxis: antihistamines versus epinephrine

Managing anaphylaxis: Epinephrine, antihistamines, and corticosteroids: More than 10 years of Cross-Canada Anaphylaxis REgistry data

BACKGROUND

Epinephrine is the first-line treatment for anaphylaxis but is often replaced with antihistamines or corticosteroids. Delayed epinephrine administration is a risk factor for fatal anaphylaxis. Convincing data on the role of antihistamines and corticosteroids in anaphylaxis management are sparse.

OBJECTIVE

To establish the impact of prehospital treatment with epinephrine, antihistamines, and/or corticosteroids on anaphylaxis management.

METHODS

Patients presenting with anaphylaxis were recruited prospectively and retrospectively in 10 Canadian and 1 Israeli emergency departments (EDs) between April 2011 and August 2022, as part of the Cross-Canada Anaphylaxis REgistry. Data on anaphylaxis cases were collected using a standardized form. Primary outcomes were uncontrolled reactions (>2 doses of epinephrine in ED), no prehospital epinephrine use, use of intravenous fluids in ED, and hospital admission. Multivariate regression was used to identify factors associated with primary outcomes.

RESULTS

Among 5364 reactions recorded, median age was 8.8 years (IQR, 3.78-16.9); 54.9% of the patients were males, and 52.5% had a known food allergy. In the prehospital setting, 37.9% received epinephrine; 44.3% received antihistamines, and 3.15% received corticosteroids. Uncontrolled reactions happened in 250 reactions. Patients treated with prehospital epinephrine were less likely to have uncontrolled reactions (adjusted odds ratio [aOR], 0.955 [95% CI, 0.943-0.967]), receive intravenous fluids in ED (aOR, 0.976 [95% CI, 0.959-0.992]), and to be admitted after the reaction (aOR, 0.964 [95% CI, 0.949-0.980]). Patients treated with prehospital antihistamines were less likely to have uncontrolled reactions (aOR, 0.978 [95% CI, 0.967-0.989]) and to be admitted after the reaction (aOR, 0.963 [95% CI, 0.949-0.977]). Patients who received prehospital corticosteroids were more likely to require intravenous fluids in ED (aOR, 1.059 [95% CI, 1.013-1.107]) and be admitted (aOR, 1.232 [95% CI, 1.181-1.286]).

CONCLUSION

Our findings in this predominantly pediatric population support the early use of epinephrine and suggest a beneficial effect of antihistamines. Corticosteroid use in anaphylaxis should be revisited.

Evidence-based use of antihistamines for treatment of allergic conditions

Available since the 1940s, H1 antihistamines are mainstay treatments for allergic conditions such as allergic rhinitis and urticaria. They function as inverse agonists that bind to the H1 receptor to inhibit histamine-induced inflammation. The older, first-generation drugs are no longer recommended for patient use because of their well-documented negative adverse effect profile. Evidence has been accumulating to support a newer generation of H1 antihistamines in oral and intranasal formulations, including in combination with intranasal corticosteroids. The literature is replete with large meta-analyses and systematic reviews establishing the safety and efficacy of second-generation H1 antihistamines in adult and pediatric allergic rhinitis populations, including combination nasal spray agents (eg, MP29-02 or MP-AzeFlu). Although intraclass differences do exist, patient preference, access, and costs should be the priority. Robust data on the regular, not as needed use of H1 antihistamines for urticaria have been published, including in the management of children and pregnant or lactating women. In addition, H1 antihistamines can be used in other related allergic conditions, such as the secondary symptoms of anaphylaxis, to provide patients with greater comfort, including in allergic asthma, depending on the individual.

Anaphylaxis management in a French pediatric emergency department: Lessons from the ANA-PED study

BACKGROUND

Anaphylaxis is a serious systemic hypersensitivity reaction that requires immediate recognition and prompt administration of epinephrine/adrenaline. The present study aimed to assess the appropriateness of epinephrine/adrenaline use in children identified as allergic by physicians in the emergency department (ED) at the time of the reaction, and to identify factors that are possibly associated with epinephrine/adrenaline administration, auto-injector prescription, and further referral to an allergist.

METHODS

We performed a retrospective cross-sectional study at the pediatric ED of the University Hospital of Montpellier, France. We included all consecutive children who attended the ED between 2016 and 2020 with an allergy-related diagnosis at discharge.

RESULTS

We included 1056 allergy-related visits, including 224 (21.2%) with a diagnosis of anaphylaxis at discharge; only 17.0% of them received an epinephrine/adrenaline injection, and 57.1% consulted an allergist after the acute episode. An auto-injector was prescribed to 63 (28.1%) patients at discharge from the ED. Besides the severity of the clinical presentation, factors associated with a guidelines-based management of the anaphylactic reaction and with an increased administration rate of epinephrine/adrenaline included presence of asthma symptoms and presence of extended skin reactions.

CONCLUSIONS

Our study underlines persistent gaps in the management of pediatric anaphylaxis in ED, focusing on hereby identified levers. By disseminating current knowledge and guidelines on anaphylaxis and allergies, specialists could work together with emergency physicians to establish effective management algorithms and improve anaphylaxis management and care pathways for children experiencing allergic reactions, especially anaphylaxis.

TRAIL REGISTRATION

Clinical Trials, number NCT05112367.

Investigation of the underuse of adrenaline (epinephrine) and prognosis among patients with anaphylaxis at emergency department admission

Background

Anaphylaxis is a potentially fatal condition; in severe cases of anaphylaxis, the cardiovascular system is often heavily involved. Adrenaline (epinephrine) is a cornerstone of the initial treatment of anaphylaxis. The use of epinephrine remains below expectations in clinical practice. Whether the underuse of epinephrine affects the prognosis of patients with anaphylaxis is still unclear.

Materials and methods

This retrospective study included patients with anaphylaxis between 2011 and 2020 who were admitted to an emergency department (ED) in Taiwan. All patients were divided into two groups based on the use of epinephrine (or not), and we compared the demographic characteristics, allergens, clinical manifestations, management, and patient outcomes.

Results

We reviewed the records of 314 subjects (216 males, 98 females; mean age: 52.78 ± 16.02 years) who visited our ED due to anaphylaxis; 107 (34.1%) and 207 (65.9%) patients were categorized into the epinephrine use group and the non-epinephrine use group, respectively. Arrival via ambulance (p = 0.019), hypotension (p = 0.002), airway compromise (p < 0.001) and altered consciousness (p < 0.001) were the deciding factors for epinephrine use among anaphylactic patients in the ED. The epinephrine use group had higher rates of other inotropic agent usage and fluid challenge. More than 90% of patients received bed rest, steroids, antihistamines, and monitoring. The epinephrine use group had a longer ED length of stay (387.64 ± 374.71 vs. 313.06 ± 238.99 min, p = 0.03) and a greater need of hospitalization. Among all severe symptoms, hypotension was the most tolerated decision factor for not using epinephrine. In this retrospective analysis, some patients with serious anaphylaxis did not experience adverse outcomes or death even without the use of epinephrine at ED admission. Emergent care focuses first on the airway, breathing, and circulation (ABC) and may compensate for the underusage of epinephrine. This could be the reason why epinephrine was underused among patients with anaphylaxis in the ED.

Conclusion

In summary, early ABC management continues to play an important role in treating patients with severe anaphylaxis, even when epinephrine is not immediately available in clinical scenarios.

Stimulation of naïve B cells with a fusion protein consisting of FlaA and Bet v 1 induces regulatory B cells ex vivo

BACKGROUND

The experimental fusion protein rFlaA:Betv1 was shown to efficiently suppress allergen-specific sensitization in mice. However, the detailed mechanism of rFlaA:Betv1-mediated immune modulation is not fully understood. In this study, we investigated the effect of rFlaA:Betv1 on naïve murine B cells.

METHODS

Immune modulating capacity of rFlaA:Betv1 was screened in IL-10 reporter mice. B cells were isolated from spleens of naïve C57Bl/6, TLR5^-/- , or MyD88^-/- mice, stimulated with rFlaA:Betv1 and controls, and monitored for the expression of the regulatory B cell markers CD1d, CD24, CD38, and surface IgM by flow cytometry. Secreted cytokines, antibodies, and reactivity of the induced antibodies were investigated by ELISA and intracellular flow cytometry. Suppressive capacity of rFlaA:Betv1-stimulated B cells was tested in mDC:CD4⁺ T cell:B cell triple cultures.

RESULTS

Upon in vivo application of rFlaA:Betv1 into IL-10-GFP reporter mice, CD19⁺ B cells were shown to produce anti-inflammatory IL-10, suggesting B cells to contribute to the immune-modulatory properties of rFlaA:Betv1. rFlaA:Betv1-induced IL-10 secretion was confirmed in human B cells isolated from buffy coats. In vitro stimulation of naïve murine B cells with rFlaA:Betv1 resulted in an mTOR- and MyD88-dependent production of IL-10 and rFlaA:Betv1 induced Bet v 1-reactive IgG production, which was not observed for IgA. rFlaA:Betv1-stimulated B cells formed a CD19⁺ CD24⁺ CD1d⁺ IgM⁺ CD38⁺ Breg subpopulation capable of suppressing Bet v 1-induced TH2 cytokine secretion in vitro.

CONCLUSION

rFlaA:Betv1 can act as a thymus-independent B cell antigen, stimulating the mTOR- and MyD88-dependent differentiation of B cells displaying a regulatory phenotype, IL-10 secretion, antigen-binding antibody production, and a suppressive capacity in vitro.

Emergency treatment of anaphylaxis: concise clinical guidance

Anaphylaxis is a serious systemic hypersensitivity reaction that is usually rapid in onset and may cause death. It is characterised by the rapid development of airway and/or breathing and/or circulation problems. Intramuscular adrenaline is the most important treatment, although, even in healthcare settings, many patients do not receive this intervention contrary to guidelines. The Resuscitation Council UK published an updated guideline in 2021 with some significant changes in recognition, management, observation and follow-up of patients with anaphylaxis. This is a concise version of the updated guideline.

Network Pharmacology Study to Elucidate the Key Targets of Underlying Antihistamines against COVID-19

Antihistamines have potent efficacy to alleviate COVID-19 (Coronavirus disease 2019) symptoms such as anti-inflammation and as a pain reliever. However, the pharmacological mechanism(s), key target(s), and drug(s) are not documented well against COVID-19. Thus, we investigated to decipher the most significant components and how its research methodology was utilized by network pharmacology. The list of 32 common antihistamines on the market were retrieved via drug browsing databases. The targets associated with the selected antihistamines and the targets that responded to COVID-19 infection were identified by the Similarity Ensemble Approach (SEA), SwissTargetPrediction (STP), and PubChem, respectively. We described bubble charts, the Pathways-Targets-Antihistamines (PTA) network, and the protein–protein interaction (PPI) network on the RPackage via STRING database. Furthermore, we utilized the AutoDock Tools software to perform molecular docking tests (MDT) on the key targets and drugs to evaluate the network pharmacological perspective. The final 15 targets were identified as core targets, indicating that Neuroactive ligand–receptor interaction might be the hub-signaling pathway of antihistamines on COVID-19 via bubble chart. The PTA network was constructed by the RPackage, which identified 7 pathways, 11 targets, and 30 drugs. In addition, GRIN2B, a key target, was identified via topological analysis of the PPI network. Finally, we observed that the GRIN2B-Loratidine complex was the most stable docking score with −7.3 kcal/mol through molecular docking test. Our results showed that Loratadine might exert as an antagonist on GRIN2B via the neuroactive ligand–receptor interaction pathway. To sum up, we elucidated the most potential antihistamine, a key target, and a key pharmacological pathway as alleviating components against COVID-19, supporting scientific evidence for further research.

The Role of Cetirizine in the Changing Landscape of IV Antihistamines: A Narrative Review

Since 1955, the only available H1 antihistamines for intravenous administration have been first-generation formulations and, of those, only intravenously administered (IV) diphenhydramine is still approved in the USA. Orally administered cetirizine hydrochloride, a second-generation H1 antihistamine, has been safely used over-the-counter for many years. In 2019, IV cetirizine was approved for the treatment of acute urticaria. In light of this approval, this narrative review discusses the changing landscape of IV antihistamines for the treatment of histamine-mediated conditions. Specifically, IV antihistamines will be discussed as a treatment option for acute urticaria and angioedema, as premedication to prevent infusion reactions related to anticancer agents and other biologics, and as an adjunct treatment for anaphylaxis and other allergic reactions. Before the development of IV cetirizine, randomized controlled trials of IV antihistamines for these indications were lacking. Three randomized controlled trials have been conducted with IV cetirizine versus IV diphenhydramine in the ambulatory care setting. A phase 3 trial of IV cetirizine 10 mg versus IV diphenhydramine 50 mg was conducted in 262 adults who presented to the urgent care/emergency department with acute urticaria requiring antihistamines. For the primary efficacy endpoint, defined as change from baseline in a 2-h patient-rated pruritus score, non-inferiority of IV cetirizine to IV diphenhydramine was demonstrated (score - 1.6 vs - 1.5, respectively; 95% CI - 0.1, 0.3). Compared with IV diphenhydramine, IV cetirizine demonstrated fewer adverse effects including less sedation, a significantly shorter length of stay in the treatment center, and fewer returns to the treatment center at 24 and 48 h. Similar findings were demonstrated in another phase 2 acute urticaria trial and in a phase 2 trial assessing IV cetirizine for pretreatment for infusion reactions in the oncology/immunology setting. IV cetirizine is associated with similar patient outcomes, fewer adverse effects, and increased treatment center efficiency than IV diphenhydramine.

Is there a doctor on the plane? A review of in-flight emergencies for the on-board radiologist

In-flight medical emergencies (IFME) are the acute on-service events involving illness or injury to a passenger with the potential for long-term health compromise. With the continuously rising number of flights available, both domestically and internationally, it is conceivable that the number of IFMEs will similarly continue to rise. Although most of these instances are relatively self-limited, the rare instance of a severe occurrence justifies preparation, both from in-flight staff and healthcare providers traveling on these flights. Given these events' sporadic nature and the variable availability of medical support, all physicians need to understand their in-flight ethical and legal capabilities, the available medical supplies, and the most likely etiologies to manage such situations successfully. Most radiologists rarely utilize the hands-on, clinical skills developed in medical school or internship for emergencies beyond allergic contrast reactions. Therefore, they may not be adept in caring for patients during an IFME. As such, we present a thorough overview and literature review for the radiologist regarding the management of various acute IFMEs, with consideration for ethical and legal precedence and a review of medical equipment available on-board.

Evidence update for the treatment of anaphylaxis

The Resuscitation Council UK has updated its Guideline for healthcare providers on the Emergency treatment of anaphylaxis. As part of this process, an evidence review was undertaken by the Guideline Working Group, using an internationally-accepted approach for adoption, adaptation, and de novo guideline development based on the Grading of Recommendations Assessment, Development and Evaluation (GRADE) evidence to decision (EtD) framework, referred to as GRADE-ADOLOPMENT. A number of significant changes have been made, which will be reflected in the updated Guideline. These include: emphasis on repeating intramuscular adrenaline doses after 5 min if symptoms of anaphylaxis do not resolve; corticosteroids (e.g. hydrocortisone) no longer being routinely recommended for the emergency treatment of anaphylaxis; interventions for reactions which are refractory to initial treatment with adrenaline; a recommendation against the use of antihistamines for the acute management of anaphylaxis; and guidance relating to the duration of observation following anaphylaxis, and timing of discharge.

Bruton's tyrosine kinase inhibition effectively protects against human IgE-mediated anaphylaxis

No known therapies can prevent anaphylaxis. Bruton's tyrosine kinase (BTK) is an enzyme thought to be essential for high-affinity IgE receptor (FcεRI) signaling in human cells. We tested the hypothesis that FDA-approved BTK inhibitors (BTKis) would prevent IgE-mediated responses including anaphylaxis. We showed that irreversible BTKis broadly prevented IgE-mediated degranulation and cytokine production in primary human mast cells and blocked allergen-induced contraction of isolated human bronchi. To address their efficacy in vivo, we created and used what we believe to be a novel humanized mouse model of anaphylaxis that does not require marrow ablation or human tissue implantation. After a single intravenous injection of human CD34+ cells, NSG-SGM3 mice supported the population of mature human tissue-resident mast cells and basophils. These mice showed excellent responses during passive systemic anaphylaxis using human IgE to selectively evoke human mast cell and basophil activation, and response severity was controllable by alteration of the amount of allergen used for challenge. Remarkably, pretreatment with just 2 oral doses of the BTKi acalabrutinib completely prevented moderate IgE-mediated anaphylaxis in these mice and also significantly protected against death during severe anaphylaxis. Our data suggest that BTKis may be able to prevent anaphylaxis in humans by inhibiting FcεRI-mediated signaling.

Anaphylaxis to three humanized antibodies for severe asthma: a case study

Background

Omalizumab, mepolizumab, benralizumab, and dupilumab are the currently available biologics used to treat asthma in Japan. Anaphylaxis following treatment with mepolizumab or benralizumab is considered rare.

Case presentation

We report the case of a 35-year-old woman with severe asthma, who experienced anaphylaxis following the administration of benralizumab, mepolizumab, and omalizumab, separately. The therapy with biologics was chosen to avoid the repeated use of systemic corticosteroids for asthma exacerbations. The mechanisms underlying anaphylaxis caused by these three biologics remain unclear. The patient’s asthma symptoms and lung function improved after treatment with bronchial thermoplasty.

Conclusions

To our knowledge, this is the first report of an asthmatic patient developing anaphylaxis after commencement of benralizumab, mepolizumab, and omalizumab therapy. These three biologics should be administered carefully, and patients should be monitored for anaphylaxis.

Evaluation of Prehospital Management in a Canadian Emergency Department Anaphylaxis Cohort

BACKGROUND

Studies assessing the use of antihistamines and corticosteroids for the treatment of anaphylaxis have not supported a conclusive effect.

OBJECTIVE

To assess prehospital management of anaphylaxis by measuring the effect of epinephrine use compared with antihistamines and corticosteroids on negative outcomes of anaphylaxis (intensive care unit/hospital ward admission, multiple doses of epinephrine in the emergency department [ED], and intravenous fluids given in the ED).

METHODS

The Cross-Canada Anaphylaxis Registry is a cohort study that enrolls anaphylaxis cases presenting to EDs in 5 Canadian provinces over a 6-year period. Participants were recruited prospectively and retrospectively and were excluded if the case did not meet the definition of anaphylaxis.

RESULTS

A total of 3498 cases of anaphylaxis, of which 80.3% were children, presented to 9 EDs across Canada. Prehospital treatment with epinephrine was administered in 31% of cases, whereas antihistamines and corticosteroids were used in 46% and 2% of cases, respectively. Admission to the intensive care unit/hospital ward was associated with prehospital treatment with corticosteroids (adjusted odds ratio, 2.84; 95% confidence interval [CI], 1.55, 6.97) while adjusting for severity, treatment with epinephrine and antihistamines, asthma, sex, and age. Prehospital treatment with epinephrine (adjusted odds ratio, 0.23; 95% CI, 0.14, 0.38) and antihistamines (adjusted odds ratio, 0.61; 95% CI, 0.44, 0.85) decreased the likelihood of receiving multiple doses of epinephrine in the ED, while adjusting for severity, treatment with corticosteroids, asthma, sex, and age.

CONCLUSIONS

Prompt epinephrine treatment is crucial. Use of antihistamines in conjunction with epinephrine may reduce the risk of uncontrolled reactions (administration of 2 or more doses of epinephrine in the ED), although our findings do not support the use of corticosteroids.

Barriers to the Administration of Epinephrine in Schools

BACKGROUND

Anaphylaxis is a serious and growing concern in the school setting as the prevalence of food allergies and food-induced severe allergic reactions continues to increase.

METHODS

A cross-sectional, web-based survey was conducted regarding anaphylactic events that occurred during the 2014-2015 school year. Eligible schools were enrolled in the EPIPEN4SCHOOLS^® program (Mylan Specialty L.P., Canonsburg, PA), which provides free epinephrine auto-injectors to qualifying US schools. Participating schools completed a 29-item survey on anaphylactic event occurrence and treatment, epinephrine stock, school policies regarding anaphylaxis, school staff training, and school nursing coverage.

RESULTS

Responses were provided by 12,275 schools. Epinephrine was administered on school property for 63.7% of reported anaphylactic events (1272/1998). In 38.5% (235/610) of events for which epinephrine was not used, antihistamines were cited as the reason. Only 59.4% of schools cited epinephrine as their standard first-line therapy for anaphylaxis. School nurses were most likely to be trained in anaphylaxis recognition and permitted to administer epinephrine; however, just 53.6% of schools had a full-time nurse on staff.

CONCLUSIONS

Process-related barriers to the appropriate use of epinephrine go beyond access to medication. Widespread staff training and review of school policies are needed to ensure that anaphylaxis is appropriately managed in schools.

Anaphylaxis management: a survey of school and day care nurses in Lebanon

OBJECTIVE

Children are at a high risk of developing allergic reactions. Since they spend lots of time at the school or day care, the odds of having an allergic event in this setting is high, hence placing the onus of properly managing their event on nurses. In Lebanon, little is known whether a standardised policy for managing allergic and anaphylactic reaction exists, leaving children unsafe and the school personnel liable. Thus, the aim of this study is to describe the current practices in the management of severe allergies and anaphylaxis by Lebanese nurses working in schools and day cares and to explore the perceived need for a protocol to manage anaphylaxis reaction.

METHODS

A cross-sectional survey with nurses working at schools and day cares in Lebanon was conducted.

RESULTS

A total of 59 school and day care nurses participated. Eighteen of the school and day care nurses reported having a written policy describing the management steps. Only 12 had witnessed an anaphylactic event. Of those, 10 reported administering an antihistamine medication orally instead of epinephrine intramuscular. Most respondents (56) believed that a standardised guideline for the management of anaphylaxis was essential, and 9 indicated being hesitant to give the epinephrine intramuscular even in the presence of a policy. Finally, 55 stated the need for training nurses in identifying and managing anaphylaxis as a must.

CONCLUSION

Currently, the management of anaphylaxis reaction in schools and day cares is suboptimal. Hence, there is a need for a standardised nursing guideline and training for nurses in these settings.

Update on the usage and safety of epinephrine auto-injectors, 2017

Anaphylaxis is a serious, potentially fatal allergic reaction. Guidelines recommend prompt intramuscular injections of epinephrine as the first-line therapy for anaphylaxis. Delayed epinephrine treatment may cause undesirable clinical outcomes, including death. In the community, epinephrine auto-injectors (EAIs) are commonly used to treat anaphylaxis. This literature review examines several recent concerns regarding the safety of EAIs that may prevent the timely administration of epinephrine. Reports of cardiovascular complications are linked with epinephrine administration, although recent studies suggest that these events are much more commonly associated with intravenous epinephrine rather than with EAIs. Recent studies have also highlighted accidental injections of EAIs in patients’ or caregivers’ fingers and lacerations associated with the use of EAI in children. However, the data suggest that both accidental injections and lacerations are rare and require limited medical intervention. In addition, patients may receive conflicting information on the safety and efficacy of using expired EAIs. Overall, it is believed that the benefits of using EAIs far outweigh the potential risks of not administering an EAI. Although legitimate safety concerns are associated with EAIs, adverse events are rare. Continued training of medical providers, caregivers, and patients may be beneficial to address these concerns and reduce EAI-associated injuries while ensuring that patients receive necessary medical care.