From the Guidelines
If you suspect a metoprolol overdose, seek emergency medical help immediately by calling 911 or poison control at 1-800-222-1222.
Treatment Overview
The treatment for metoprolol overdose involves a combination of supportive care and specific antidotes to counteract the cardiovascular effects.
- Medical professionals may administer activated charcoal if the overdose was recent.
- Specific antidotes like glucagon (1-5 mg IV initially, followed by infusion) or intravenous calcium salts may be used to counteract the cardiovascular effects 1.
- Atropine (0.5-1 mg IV) may be given for bradycardia, and vasopressors like norepinephrine or epinephrine might be needed for hypotension.
High-Dose Insulin Therapy
In severe cases, high-dose insulin therapy (1 unit/kg bolus followed by infusion) with glucose supplementation may be used to treat metoprolol overdose, as it has been shown to be effective in refractory shock due to beta-blocker overdose 1.
- The insulin infusion is titrated as needed to achieve adequate hemodynamic response, whereas the dextrose infusion is titrated to maintain serum glucose concentrations of 100 to 250 mg/dL (5.5 to 14 mmol/L).
- Moderate hypokalemia is common during high-dose insulin-euglycemia therapy, and potassium levels should be targeted between 2.5 to 2.8 mEq/L to avoid overly aggressive potassium repletion 1.
Extracorporeal Treatment
Extracorporeal treatment, such as hemodialysis, may be considered in severe cases of metoprolol overdose, although its effectiveness is limited due to the large volume of distribution of the drug 1.
- The amount of metoprolol removed by hemodialysis is approximately 3.3% of the ingested dose, and clearance ranges from 20 to 48 mL/min 1.
- Continuous kidney replacement therapy (CKRT) and hemoperfusion may also be used, but their effectiveness is limited and variable 1.
From the Research
Treatment for Metoprolol Overdose
The treatment for metoprolol overdose is primarily focused on managing the cardiotoxic effects of the drug. Some key considerations include:
- Close monitoring of the patient's vital signs and cardiac function 2, 3
- Use of supportive care, such as pacing and hospitalization, to manage symptoms like hypotension and bradycardia 3
- Administration of high-dose insulin therapy, which has been shown to be effective in combination with vasoconstrictors/inotropes 4
- Consideration of extracorporeal life support in severe cases of toxicity, particularly when multiple cardioactive medications are involved 5
Management of Cardiovascular Toxicity
Cardiovascular toxicity due to metoprolol poisoning can be severe and may require aggressive management, including:
- Use of transvenous cardiac pacing to manage refractory bradydysrhythmia 5
- Administration of intravenous calcium, glucagon, vasopressors, and lipid emulsion to support cardiac function 5
- Monitoring for signs of cardiac dysfunction, such as ST segment elevation and junctional dysrhythmia, and managing these conditions accordingly 3
Special Considerations
Certain patient populations, such as those with coronary artery disease, may be at increased risk for cardiovascular toxicity due to metoprolol overdose 3. Additionally, patients who are poor CYP2D6 metabolizers may be at risk for prolonged zero-order elimination of metoprolol, leading to increased toxicity 4.