What are the effects of beta blocker (beta-adrenergic blocking agent) overdose?

From the Guidelines

Beta blocker overdose is a life-threatening condition that requires immediate medical attention, and the primary treatment involves supportive care, intravenous glucagon, and high-dose insulin therapy. Treatment begins with supportive care including airway management, oxygen, and cardiac monitoring. For symptomatic patients, activated charcoal may be administered if the ingestion was recent (within 1-2 hours) 1. The primary antidote is intravenous glucagon, typically given as a 5-10 mg bolus followed by an infusion of 1-5 mg/hour titrated to response. High-dose insulin therapy (1 unit/kg bolus followed by 0.5-1 unit/kg/hour) with glucose supplementation is effective for cardiovascular depression, as recommended by the 2020 American Heart Association guidelines for cardiopulmonary resuscitation and emergency cardiovascular care 2.

Key Treatment Modalities

• Intravenous glucagon: 5-10 mg bolus followed by an infusion of 1-5 mg/hour titrated to response
• High-dose insulin therapy: 1 unit/kg bolus followed by 0.5-1 unit/kg/hour with glucose supplementation
• Supportive care: airway management, oxygen, and cardiac monitoring
• Activated charcoal: may be administered if the ingestion was recent (within 1-2 hours)

For bradycardia and hypotension, atropine (0.5-1 mg IV), calcium chloride (1 g IV), or calcium gluconate (3 g IV) may be used, although the evidence for these treatments is not as strong 2. Vasopressors like epinephrine or norepinephrine are indicated for persistent hypotension. Severe cases may require cardiac pacing or extracorporeal membrane oxygenation, as mentioned in the 2021 systematic review and recommendations from the EXTRIP workgroup 3.

Additional Considerations

• Extracorporeal life support (ECLS) may be required in severe cases
• Cardiac pacing may be necessary for severe bradycardia
• The severity of beta blocker overdose depends on the specific beta blocker, dose, and patient factors, with lipophilic agents like propranolol potentially causing more severe central nervous system effects.

From the Research

Overview of Beta Blocker Overdose

• Beta-blocker overdose can lead to severe morbidity and mortality, with common clinical findings including bradycardia and hypotension 4.
• The management of beta-blocker overdose involves supportive care, cardiac monitoring, and specific treatments such as administration of calcium salts, vasopressors, and high-dose insulin euglycaemia treatment 4, 5.

Treatment of Beta Blocker Overdose

• Gastric decontamination with activated charcoal may be considered, but its effectiveness is unclear due to concurrent use of multiple interventions 6.
• Catecholamines, inotropes, and vasopressors may provide a survival benefit and improve haemodynamics 6.
• High-dose insulin euglycaemic therapy has been associated with improved haemodynamics and mortality benefit, but its use is often accompanied by hypoglycaemia and hypokalemia 6.
• Glucagon has been associated with minor improvements in haemodynamics, particularly in increasing heart rate 6.
• Other treatments, such as methylthioninium chloride, intravenous lipid emulsion therapy, and lignocaine, have variable responses and are not well-established 6.

Management Guidelines

• Patients with suspected beta-blocker overdose should be referred to an emergency department immediately if they have evidence of self-harm or have ingested a potentially toxic dose 7.
• Asymptomatic patients who have ingested a beta-blocker should be monitored for at least 6-12 hours, depending on the type of beta-blocker and the time of ingestion 7.
• Ambulance transportation is recommended for patients who are referred to emergency departments due to the potential for life-threatening complications 7.
• Follow-up calls should be made to determine outcome at appropriate intervals for up to 12-24 hours 7.

Clinical Toxicology

• Beta-blocker overdose can cause significant toxicity due to its strong blood pressure-lowering and heart rate-lowering effects 8.
• A 10-year retrospective analysis of the Mainz Poison Center/Germany database found that metoprolol was the most frequently reported beta-blocker, followed by bisoprolol, atenolol, propranolol, and sotalol 8.
• Symptoms of beta-blocker overdose did not differ substantially among different beta-blockers, except for more seizures being reported with propranolol and more CNS depression/vomiting with sotalol 8.