What routes are appropriate for administering glucagon in beta-blocker overdose?

• A. PO
• B. IM/IV/IO
• C. Subcutaneous
• D. Inhaled

Answer: (B)

In beta-blocker overdose, you need a way to increase heart rate and contractility despite beta-adrenergic blockade. Glucagon works by activating its own receptors to raise cAMP in cardiac cells, producing positive inotropic and chronotropic effects that bypass the blocked beta receptors. For EMS emergencies, the fastest, most reliable delivery methods are routes that can be used quickly and reach the circulation promptly: intramuscular, intravenous, or intraosseous. If IV access is available, giving glucagon IV provides the quickest onset. If IV access isn’t yet established, intraosseous delivery is a practical alternative to get the drug into the circulation rapidly. Intramuscular administration is also effective and commonly used when IV/IO access is delayed.

Oral and subcutaneous routes have slower, variable absorption and are not ideal in a life-threatening overdose where rapid hemodynamic support is required. Inhaled glucagon isn’t a standard or reliable route for this indication and isn’t used in this scenario.