In this episode, I’ll discuss whether patients taking beta-blockers require increased doses of epinephrine for anaphylaxis.
Animal data suggests that patients taking beta-blockers have more severe anaphylaxis, possibly by decreasing the threshold for mast cell activation.
With beta-blockers interfering with the same receptors epinephrine needs to activate in order to effectively treat anaphylaxis, there is concern that such patients may need higher doses of epinephrine or even an alternate treatment approach that is not dependant on beta-receptor availability such as glucagon.
In order to determine whether the risk of requiring more than 1 dose of epinephrine for the treatment of anaphylaxis is increased among ED patients taking beta-blockers, a group of researchers conducted a retrospective observational single-center study of ED patients with anaphylaxis. Nearly 800 patients were analyzed and the study was powered to detect a 10% or greater difference in the need for repeat epinephrine administration between patients who were and were not taking b-blocker medications.
11% of the patients with anaphylaxis were taking a beta-blocker. A small number of patients in the cohort needed more than 1 dose of epinephrine (only 8%). Of the patients taking a beta-blocker, 13% required more than one dose however this difference was not statistically significant with a p value of 0.56.
When the authors applied multivariate analysis, the association of beta-blocker use with the need for more than 1 dose of epinephrine remained statistically nonsignificant after adjusting for age, sex, precipitating allergen, COPD, and cardiovascular disease.
Therefore, despite having a physiologic rationale, the authors concluded that:
…our results demonstrate that after controlling for COPD and cardiovascular comorbid conditions, age, and sex, the use of b-blockers was not associated with at least a 10% increase in the need for more than 1 dose of epinephrine. Although it is possible that the risk of repeat epinephrine is smaller than 10%, the clinical significance of this is uncertain and may not outweigh the benefits of b-blockers for other conditions.
The practical application of this data is that, even for patients taking beta-blockers, epinephrine at the standard dose is the first-line treatment for anaphylaxis.
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