Treatment of Metoprolol Toxicity
The treatment of metoprolol toxicity requires aggressive management with high-dose insulin and vasopressors as first-line therapies, followed by additional supportive measures based on clinical presentation.
Initial Assessment and Management
- Assess for bradycardia, hypotension, altered mental status, and hypoglycemia
- Secure airway, breathing, and circulation
- Obtain ECG, continuous cardiac monitoring, and blood glucose levels
- Consider activated charcoal for recent ingestions (within 1-2 hours) if airway is protected 1
First-Line Pharmacological Interventions
Vasopressors (Class 1, C-LD)
- Start immediately for hypotension to maintain adequate perfusion
- Options include epinephrine, norepinephrine, and dopamine
- Titrate to effect based on blood pressure response 2, 1
High-Dose Insulin Euglycemic Therapy (HIET) (Class 1, B-NR)
- Administer 1 U/kg IV bolus followed by infusion starting at 1 U/kg/hour
- Titrate up to clinical effect (may require higher doses)
- Monitor glucose every 15-30 minutes initially
- Supplement with dextrose as needed to maintain euglycemia
- Continue for 24-36 hours in severe cases 2, 1, 3
Second-Line Interventions
Glucagon (Class 2a, C-LD)
- Administer 5-10 mg IV bolus over 3-5 minutes
- Follow with continuous infusion of 1-5 mg/hour
- Be prepared for potential vomiting as a side effect 2, 1
Atropine (Class 2b, C-LD)
- Use for symptomatic bradycardia: 0.5-1 mg IV
- May repeat to maximum of 3 mg
- Note: Often has limited efficacy in beta-blocker overdose 2, 1
Calcium (Class 2b, C-LD)
- Consider calcium chloride (10-20 mL IV) or calcium gluconate (30-60 mL IV)
- May repeat every 10-20 minutes for 3-4 doses if beneficial 1
Advanced Interventions for Refractory Cases
Extracorporeal Life Support (Class 2a, C-LD)
- Consider VA-ECMO for life-threatening poisoning with cardiogenic shock refractory to pharmacological interventions
- Early consultation with ECMO team recommended 2, 1
Cardiac Pacing (Class 2b, C-LD)
- Consider for persistent symptomatic bradycardia unresponsive to medical therapy
- May have limited efficacy due to myocardial depression 2, 1
Hemodialysis (Class 2b, C-LD)
- May be considered for severe metoprolol toxicity, particularly with renal impairment
- Most effective for water-soluble beta-blockers with low protein binding 2
Intravenous Lipid Emulsion (ILE) (Class 3: No Benefit, C-LD)
- Not recommended as routine therapy for beta-blocker poisoning
- Limited evidence for efficacy despite some case reports 2, 3
Monitoring and Support
- Continuous cardiac monitoring
- Frequent blood pressure measurements
- Serial ECGs
- Blood glucose and potassium levels
- Lactate levels to assess tissue perfusion 1
Special Considerations
- Metoprolol toxicity can cause direct myocardial depression leading to bradycardia, hypotension, and cardiovascular collapse 3
- Severe toxicity may require multiple treatment modalities simultaneously
- Patients with co-ingestions (especially other cardiovascular medications) may have worse outcomes 4
- Symptoms typically appear within 2-6 hours of ingestion but may be delayed with sustained-release formulations 4