Management of Bradycardia from Metoprolol Overdose

Initial Assessment and Management

The American Heart Association recommends immediate discontinuation of metoprolol and implementation of supportive measures, including vasopressors, glucagon administration, and high-dose insulin-euglycemia therapy, as the most effective interventions for patients with bradycardia due to excessive metoprolol 1
Monitoring of heart rate, blood pressure, and ECG should be done continuously in patients with metoprolol-induced bradycardia 1
Secure IV access for administration of medications is recommended for patients with metoprolol overdose 1

The American College of Cardiology recommends titrating vasopressors, such as norepinephrine or dopamine, to maintain adequate blood pressure and tissue perfusion in patients with metoprolol-induced hypotension 1
Glucagon administration, 3-10 mg IV slowly over 3-5 minutes, followed by infusion of 3-5 mg/hour, is recommended for patients with metoprolol-induced bradycardia 1
Glucagon works by activating adenylyl cyclase through a non-beta receptor mechanism, bypassing the blocked beta receptors, and should be administered with caution to prevent vomiting 1

High-dose insulin-euglycemia therapy, consisting of 1 U/kg regular insulin as IV bolus with 0.5 g/kg dextrose, followed by infusion at 0.5-1 U/kg/hour of insulin and 0.5 g/kg/hour of dextrose, is recommended for patients with metoprolol-induced bradycardia 1
Monitoring of serum glucose every 15-30 minutes initially, then every 1-2 hours once stable, and targeting glucose levels of 100-250 mg/dL, is recommended for patients receiving high-dose insulin-euglycemia therapy 1
Moderate hypokalemia (2.5-2.8 mEq/L) is acceptable during high-dose insulin-euglycemia therapy, but potassium levels should be monitored closely 1
IV calcium administration, 0.3 mEq/kg of calcium over 5-10 minutes, followed by infusion of 0.3 mEq/kg/hour, may be considered in refractory cases of metoprolol-induced bradycardia 1

When restarting beta-blocker therapy after resolution of metoprolol-induced bradycardia, consider starting at a lower dose with gradual titration, and more frequent monitoring of heart rate and symptoms, to prevent recurrence 2