Intravenous Cetirizine Versus Intravenous Diphenhydramine for the Treatment of Acute Urticaria: A Phase III Randomized Controlled Noninferiority Trial

Treatment of acute urticaria: A systematic review

There are only a few clinical trials which address the treatment of acute urticaria (AU). Especially, the added value of systemic corticosteroids to antihistamines is unclear in treatment of severe AU. To review the existing evidence-based approaches for AU treatment. A systematic electronic search was done in PubMed and Web of Science to retrieve all studies on the treatment of patients with AU. A descriptive synthesis was conducted based on the PRISMA statement. Quality assessment was independently performed by both reviewers ('Cochrane risk-of-bias tool' for RCTs). Ten randomized controlled trials (RCTs) (n = 857 participants) were included. Four studies assessed corticosteroid effectiveness added to antihistamines and six studies compared the efficacy of H1 and/ or H2-antihistamines. The addition of corticosteroid (prednisone) to an antihistamine (levo)cetirizine did not improve symptoms of AU compared to antihistamine alone in two out of three RCTs. The combination of diphenhydramine (50 mg, IV) and ranitidine (50 mg, IV) or cimetidine (300 mg, IV) was most efficient for relief of urticaria in two out of five studies. Most frequent adverse effects were sedation and drowsiness. Recent guidelines on urticaria treatment mainly focus on chronic urticaria rather than on AU. Moreover, only few, small RCTs provide evidence for the management of AU. Thus, the state-of-the-art management of this frequent condition remains unclear. The addition of corticosteroids to an antihistamine as treatment for AU needs to be further investigated. Well-designed, high-quality interventional trials are needed to establish evidence-based treatment guidelines for AU.

Evaluation of Pharmacological Treatments for Acute Urticaria: A Systematic Review and Meta-Analysis

BACKGROUND

The effectiveness and safety of pharmacological treatments for acute urticaria remain unclear.

OBJECTIVE

To systematically review and meta-analyze the efficacy and safety of pharmacological treatments for acute urticaria in emergency department (ED) and non-ED settings.

METHODS

We searched electronic databases and gray literature up to July 8, 2023, without language restrictions. Randomized clinical trials (RCTs) relating to pharmacological interventions in patients with acute urticaria, regardless of age, were eligible for inclusion. The relevant outcomes of interest were the treatment efficacy and safety profiles. The results are presented as standardized mean differences (SMDs) or odds ratios (ORs).

RESULTS

We identified 8 RCTs comprising 680 patients. Regarding the ED setting (2 trials, n = 118), intramuscular first-generation H1-antihistamine (fgAH) was more efficacious in decreasing pruritus symptoms (SMD, -0.38; 95% confidence interval [CI], -0.75 to -0.02) but had higher sedative effects than H2-blockers. With comparable pruritus symptom improvement (2 trials, n = 295), intravenous second-generation H1-antihistamine (sgAH) had favorable clinical outcomes compared with intravenous fgAH in the ED setting with a lower risk of return to any ED/clinic (OR, 0.31; 95% CI, 0.12-0.83) and lower risk of any adverse event (OR, 0.24; 95% CI, 0.09-0.63). The efficacy of adjunctive therapy with a short course of systemic glucocorticosteroids in ED and non-ED settings remains unclear. No serious concerns regarding the safety profiles were observed in any of the treatment comparisons.

CONCLUSIONS

H1-antihistamine is a crucial and effective component of acute urticaria treatment, and intravenous sgAH is preferred as an initial treatment option.

Diphenhydramine: Time to Move on?

Diphenhydramine is one of the most widely available, longest-used antihistamine medications but has many side effects including sedation and risk of toxicity in overdose including cardiac toxicity. It is frequently inappropriately used when newer, more favorable antihistamine medications are available. Second-generation antihistamines are also widely available and affordable, with many of the same desired effects as diphenhydramine and fewer, if any, of the undesirable side effects. Because of the negative side effects and wide availability of alternative antihistamine medications, it is definitively time to move on from diphenhydramine.

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.

Intravenous Cetirizine vs Intravenous Diphenhydramine for the Prevention of Hypersensitivity Infusion Reactions: Results of an Exploratory Phase 2 Study

Pretreatment with antihistamines for the prevention of hypersensitivity infusion reactions is recommended for certain biologics and chemotherapies. Cetirizine is the first injectable second-generation antihistamine recently approved for acute urticaria. A randomized, exploratory phase 2 study evaluated intravenous (IV) cetirizine 10 mg versus IV diphenhydramine 50 mg as pretreatment in patients receiving an anti-CD20 agent or paclitaxel. In the overall population (N = 34) and an elderly subgroup (n = 21), IV cetirizine was as effective as IV diphenhydramine in preventing infusion reactions (primary outcome) and associated with less sedation at all time points, a shorter infusion center stay, and fewer treatment-related adverse events.

State-of-the-Art on Biomarkers for Anaphylaxis in Obstetrics

Anaphylaxis is an unpredictable systemic hypersensitivity reaction and constitutes a high risk of maternal and fetal morbidity and mortality when occurring during pregnancy. Currently, the acute management of anaphylaxis is based on clinical parameters. A total serum tryptase is only used to support an accurate diagnosis. There is a need to detect other biomarkers to further assess high-risk patients in obstetrics. Our objective is to present biomarkers in this complex interdisciplinary approach beyond obstetrician and anaesthetic management. Candidate biomarkers derive either from mediators involved in immunopathogenesis or upcoming molecules from systems biology and proteomics. Serum tryptase is determined by singleplex immunoassay method and is important in the evaluation of anaphylactic mast cell degranulation but also in the assessment of other risk factors for anaphylaxis such as systemic mastocytosis. Another category of biomarkers investigates the IgE-mediated sensitization to triggers potentially involved in the etiology of anaphylaxis in pregnant women, using singleplex or multiplex immunoassays. These in vitro tests with natural extracts from foods, venoms, latex or drugs, as well as with molecular allergen components, are useful because in vivo allergy tests cannot be performed on pregnant women in such a major medical emergency due to their additional potential risk of anaphylaxis.