American Board of Family Medicine (ABFM) Practice Exam 2026 - Free ABFM Practice Questions and Study Guide

In the context of a patient experiencing an anaphylactic reaction while on a beta-blocker, the administration of epinephrine is the first-line treatment. However, patients on beta-blockers may not respond as effectively to epinephrine due to the blockade of beta-adrenergic receptors, which can lead to inadequate counteraction of the anaphylactic response.

When there is no improvement after the initial dose of epinephrine, the administration of glucagon is particularly relevant. Glucagon acts on glucagon receptors, increasing intracellular cyclic AMP (cAMP) levels and effectively bypassing the beta-adrenergic blockade. Thus, glucagon can help restore cardiovascular stability and improve heart rate and contractility, making it a key alternate rescue medication in this scenario.

In contrast, administering another dose of intramuscular epinephrine might not be effective because the beta-blockade can prevent the optimal response. Intravenous methylprednisolone and intravenous diphenhydramine would not provide the immediate physiological effects needed in a life-threatening anaphylactic reaction, as they take longer to exert their actions. Thus, glucagon is the most appropriate choice to aid in managing the anaphylactic reaction effectively.