What is the antidote for propranolol (beta blocker) overdose?

Antidotes for Propranolol Overdose

For propranolol overdose, high-dose glucagon is the primary antidote, administered as 50-150 mcg/kg IV bolus followed by a continuous infusion of 1-5 mg/hour. 1 Propranolol is not significantly dialyzable, making pharmacological interventions essential for managing toxicity.

First-Line Treatment: Glucagon

Glucagon is the most effective antidote for propranolol overdose because it:

• Bypasses the blocked β-receptors by activating adenylyl cyclase directly
• Exerts potent inotropic and chronotropic effects
• Is particularly useful for treating hypotension and depressed myocardial function 1

Administration protocol:

• Initial bolus: 50-150 mcg/kg IV
• Maintenance: Continuous infusion of 1-5 mg/hour
• Titrate to achieve adequate hemodynamic response
• Plan for adequate glucagon supply as treatment may require >100 mg in 24 hours 2

Second-Line Treatments

High-Dose Insulin with Glucose

• Reasonable for refractory shock (Class 2a recommendation) 2
• Typical dosing: 1 U/kg IV bolus, followed by 1 U/kg/hour infusion
• Requires glucose supplementation and electrolyte monitoring
• Improves myocardial energy utilization 2

Calcium

• May be considered for refractory shock (Class 2b recommendation) 2
• Limited animal data and case reports suggest moderate elevation of blood pressure 3
• Less effective than glucagon but may provide additional benefit

Vasopressors

• Epinephrine is preferred for severe hypotension
• Caution: Epinephrine may provoke uncontrolled hypertension 1
• Dopamine and norepinephrine can antagonize propranolol-induced hypotension 3

Refractory Cases

For shock refractory to pharmacological therapy:

• ECMO might be considered (Class 2b recommendation) 2
• Particularly valuable in massive overdoses (≥2,000 mg propranolol) 4
• The EXTRIP workgroup assessed propranolol as non-dialyzable, making ECMO more appropriate than hemodialysis 2

Important Caveats

1. Dose-toxicity relationship: Severe toxicity is common with doses ≥2,000 mg, occurring in approximately 53% of isolated propranolol overdoses at this threshold 4

2. Monitoring requirements:

   • Continuous ECG monitoring
   • Frequent blood pressure checks
   • Neurobehavioral status assessment
   • Intake and output balance 1

3. Potential complications:

   • Glucagon commonly causes vomiting; protect airway in CNS-depressed patients 2
   • Bradycardia may require temporary cardiac pacing 1
   • Seizures may occur with higher doses 4

4. Avoid atropine alone as it has shown limited efficacy in propranolol overdose 3

5. Isoproterenol may be useful for bronchospasm but requires careful monitoring due to potential for hypotension 1

The management of propranolol overdose requires aggressive intervention with glucagon as the cornerstone therapy, with additional measures implemented based on clinical response and severity of toxicity.