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Discover the efficacy of combining H1 and H2 blockers in treating acute allergic syndromes, as explored in a randomized study conducted on adult patients with symptoms like angioedema, stridor, and pruritic rash. Explore the study design, findings, and limitations in this insightful research.
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H2 Blockers in Allergic Reactions Maureen Chase
The Study • Improved Outcomes in Patients with Acute Allergic Syndromes who are Treated with combined H1 and H2 Antagonists • Lin, et al, Annals of Emergency Medicine Nov 2000
Study Design • Randomized double blind placebo controlled study of 91 patients with acute allergic syndromes in an urban academic center ER • Control Group- 50 mg IV benadryl and saline solution • Study group- 50 mg IV benadryl and 50 mg Ranitidine
Patient Sample • Adults > 18 yo • Acute angioedema, acute unexplained stridor and acute pruritic rash • Symptoms present < 12 hrs from time of exposure to presumed allergen ( ingested food, inhaled or injected drug or contact with latex)
Endpoint • Resolution Urticaria, angioedema and erythema at 2 hours
Study conclusions • Significant difference between study and control group of resolution of urticaria alone and urticaria with angioedema • NO difference between groups w/r/t angioedema alone or erythema in presence or absence of urticaria
Study Flaws, cont. • No Ranitidine + saline group
Background • Histamine anatgonists in the treatment of acute allergic reactions • Runge, et al, Annals of Emer Med Mar 1992 • visual analog scale assessment of allergic symptoms in 35 patients at presentation and 30’ after treatment with cimetidine and diphemhydramine, alone or in combination
Runge, et al, cont. • H1 and H2 blockers combined are more effective than H1 blockers alone in the treatment of urticaria ( p = 0.027) • FLAW- small sample size
HUPisms • Studies suggest possible benefit of H2 blockers in treatment of some aspects of allergic response ( urticaria) • Current data DO NOT support use of H2 blockers in treatment of all acute allergic reactions • ** Seems reasonable but no clear benefit**