In beta-blocker overdose, how is glucagon used and what is the typical dosing regimen?

• A. Bolus 3–5 mg IV, then 3–5 mg/hour infusion
• B. Bolus 1–2 mg IV, then 1–2 mg/hour infusion
• C. Bolus 10 mg IV, then 10 mg/hour
• D. Bolus 0.5 mg IV, then 0.5 mg/hour

Answer: (A)

In beta-blocker overdose, glucagon works by bypassing the blocked beta receptors. It binds to glucagon receptors on the heart, increasing intracellular cyclic AMP and calcium signaling, which raises heart rate and contractility and helps improve blood pressure even when beta-adrenergic signaling is inhibited.

The typical regimen starts with a small IV bolus to kick-start the effect, followed by a continuous IV infusion at a similar dose level per hour, with the dose gradually titrated based on the patient’s response (heart rate, blood pressure, perfusion). If the response isn’t adequate, the infusion rate can be increased while closely monitoring for effects. Be mindful of potential side effects such as nausea and vomiting, hyperglycemia, and tachyarrhythmias, and use glucagon as part of a broader resuscitation strategy alongside fluids and other supportive therapies.