Intravenous injection cetirizine vs intravenous injection diphenhydramine in treatment of acute urticaria

Document Type

Conference Proceeding

Publication Date


Publication Title

Acad Emerg Med


Background: Acute urticaria, the most common symptom of acute allergic reactions, is a frequent presentation in the Emergency Department (ED). Diphenhydramine injection, the only available antihistamine injection, is sedating, short in duration with anticholinergic side effects. Cetirizine injection 10 mg/ mL, a recent innovation in antihistamine pharmacology, minimizes these problems. A phase III clinical trial using a newly developed IV cetirizine was compared to IV diphenhydramine in treatment of acute urticaria. Methods: Adult subjects who presented to EDs and Urgent Care Centers with acute urticaria and in need of IV antihistamine injections were randomized to either IV cetirizine 10 mg or IV diphenhydramine 50 mg. Primary endpoint was the 2-h pruritus score change from baseline. Key secondary endpoints were time spent in treatment center and need to return to ED/clinic. Patient sedation was scored at 1 h, 2 h, and discharge. Other secondary endpoints (rescue drugs, symptom recurrence, etc.) were also measured. Results: Adult subjects (n=262) were enrolled from March 2017 to April 2018. The 2-hour pruritus score change from baseline from IV cetirizine was demonstrated to be statistically non-inferior to IV diphenhydramine, and in favor of cetirizine. Time spent in treatment center was 2.1 h in the diphenhydramine group vs 1.7 h in cetirizine (per protocol p=0.0024). Return to ED/Clinic was 14.0% in the diphenhydramine group and 5.5% in cetirizine (p=0.0232). There was significantly less sedation in the cetirizine group at 1h (p=0.0034), 2 h (p=0.0292), and at discharge (p=0.0443) compared to diphenhydramine. There were significantly fewer adverse events (AEs) (p=0.0083) and fewer rescue drug usages (p=0.0159) reported in subjects treated with cetirizine compared to diphenhydramine. Conclusion: This study demonstrates IV cetirizine as an effective alternative to IV diphenhydramine in the treatment of acute urticaria with benefits of less sedation, less AEs, less symptom recurrence, less rescue drug use, shorter time spent in treatment center and less return to treatment center.



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