Beta Blocker and Calcium Channel Blocker Overdose — High-Dose Insulin

Key Points

• Treat the shock phenotype, not just the drug name: severe poisoning can be cardiogenic, vasoplegic, bradycardic, or mixed.
• Hyperglycemia strongly supports significant CCB toxicity, while hypoglycemia can occur with beta-blocker poisoning.
• Vasopressors are recommended for hypotension in life-threatening beta-blocker and CCB poisoning.
• High-dose insulin should be used for hypotension in severe CCB poisoning and for beta-blocker shock refractory to vasopressors.
• Give calcium in life-threatening CCB poisoning and titrate to hemodynamic response and ionized calcium.
• Glucagon is an adjunct for beta-blocker poisoning but should not delay high-dose insulin and vasopressor therapy in severe shock.
• Frequent glucose and potassium monitoring is mandatory during high-dose insulin therapy.
• VA-ECMO can be lifesaving in refractory cardiogenic shock from a reversible beta-blocker or CCB overdose.

Algorithm

1. Assess airway, breathing, circulation, mental status, ECG, glucose, and hemodynamic phenotype.
2. Establish IV access and continuous monitoring; obtain electrolytes, ionized calcium, renal function, blood gas, lactate, and targeted coingestant studies.
3. Treat symptomatic bradycardia with atropine while preparing definitive antidotal and vasoactive therapy.
4. Begin vasopressor support for hypotension, selecting epinephrine, norepinephrine, or combination therapy according to cardiogenic versus vasoplegic physiology.
5. For significant CCB toxicity, administer IV calcium and reassess blood pressure, conduction, and ionized calcium.
6. Initiate high-dose regular insulin with protocolized glucose and potassium monitoring for severe CCB hypotension or refractory beta-blocker shock.
7. For beta-blocker poisoning, add glucagon when appropriate and manage sodium-channel blockade or QT toxicity if the specific agent causes it.
8. Use bedside echocardiography and perfusion markers to determine whether myocardial depression or vasoplegia remains dominant.
9. Escalate refractory shock to toxicology, cardiology, and an ECMO-capable center; consider methylene blue or lipid therapy only in selected refractory situations.
10. Continue prolonged monitoring after extended-release or long-acting ingestion even when initial hemodynamics improve.

Clinical Synopsis & Reasoning

Beta-blockers and calcium-channel blockers are common cardiovascular medications with potentially lethal overdose syndromes. Both can cause bradycardia, atrioventricular block, hypotension, myocardial depression, and shock, but the phenotype depends on the specific drug. Non-dihydropyridine CCBs such as verapamil and diltiazem prominently depress nodal conduction and contractility, whereas a large dihydropyridine overdose such as amlodipine may initially produce profound vasodilatory shock with relatively preserved or even increased heart rate before myocardial depression develops. Beta-blockers vary in beta selectivity, membrane-stabilizing sodium-channel activity, lipophilicity, intrinsic sympathomimetic activity, and renal elimination.

Metabolic findings can help distinguish the syndromes. CCB poisoning often causes hyperglycemia because pancreatic calcium-channel blockade reduces insulin release and stressed myocardium becomes relatively insulin resistant. Beta-blocker toxicity more often produces normal or low glucose, particularly in children, although overlap is common. Lipophilic beta-blockers such as propranolol can cause seizures and coma. Propranolol and some other agents also block fast sodium channels, producing QRS widening that requires sodium bicarbonate in addition to therapy for beta blockade. Sotalol can cause substantial QT prolongation and torsades risk.

Obtain a detailed medication history, formulation, dose, time, and possible coingestants, but treat the hemodynamic phenotype rather than waiting for drug concentrations. Extended-release preparations can produce delayed or prolonged toxicity. Bedside echocardiography is especially useful because it distinguishes predominant myocardial pump failure from severe vasodilatory shock and helps guide the balance of insulin, vasopressor, and mechanical support. Frequent glucose, potassium, ionized calcium, acid-base, and perfusion assessment is essential during antidotal therapy.

Treatment Strategy & Disposition

Support airway and ventilation, establish large-bore IV access, use continuous ECG monitoring, and correct life-threatening hypoglycemia, hyperkalemia, or other abnormalities. Carefully selected activated charcoal or whole-bowel irrigation may be considered for significant recent or extended-release ingestion when the airway and hemodynamics are sufficiently stable, ideally after toxicology consultation. Atropine can be attempted for symptomatic bradycardia but is often ineffective in severe poisoning, so escalation should not be delayed.

Vasopressors are recommended for hypotension in life-threatening beta-blocker and CCB poisoning. Epinephrine is useful when bradycardia and myocardial depression predominate, while norepinephrine is often useful for severe vasoplegia; many patients require more than one agent. In CCB poisoning, administer IV calcium to increase extracellular calcium and improve contractility and vascular tone. The 2025 AHA antidote table lists adult initial doses of 2 g calcium chloride or 6 g calcium gluconate, with repeat or infusion dosing titrated to blood pressure and ionized calcium. Central administration is preferred for concentrated calcium chloride because extravasation can cause severe tissue injury.

High-dose insulin euglycemia therapy is a core treatment for severe CCB poisoning and for beta-blocker hypotension refractory to vasopressors. Regular insulin improves myocardial carbohydrate utilization and inotropy. The AHA table lists a 1 unit/kg IV initial dose followed by 1 to 10 units/kg per hour. Give dextrose as needed to maintain euglycemia, except that markedly hyperglycemic CCB patients may not initially require a dextrose bolus. Check glucose very frequently during initiation and after dose changes, then at widening intervals once stable. Potassium shifts intracellularly during treatment; monitor it closely and replace judiciously, recognizing that moderate hypokalemia reflects redistribution rather than total-body depletion.

Glucagon can improve heart rate and contractility in beta-blocker poisoning independent of beta receptors. AHA guidance considers a bolus followed by infusion reasonable for symptomatic bradycardia or hypotension, with an adult bolus range of 2 to 10 mg and infusion 1 to 15 mg per hour. Nausea and vomiting are common. Glucagon benefit in CCB poisoning is uncertain and it should not displace insulin, calcium, and vasopressors. Intravenous lipid emulsion has uncertain benefit for refractory beta-blocker toxicity and is not routine. Methylene blue can be considered by experienced teams for refractory vasoplegic shock from CCB poisoning, particularly amlodipine, after standard therapies. VA-ECMO is reasonable for refractory cardiogenic shock or cardiac arrest when poisoning is potentially reversible. Hemodialysis may help selected severe atenolol, nadolol, or sotalol poisonings but is not useful for most CCBs and many highly protein-bound beta-blockers.

Epidemiology / Risk Factors

• CCBs and beta-blockers are among the cardiovascular drugs most associated with severe poisoning and toxicologic shock.
• Extended-release verapamil, diltiazem, metoprolol, and other formulations can cause delayed deterioration.
• Amlodipine overdose often produces prolonged vasoplegia because of its long half-life.
• Propranolol is notable for CNS penetration, seizure risk, and sodium-channel blockade at toxic doses.
• Atenolol, nadolol, and sotalol have sufficient extracorporeal clearance characteristics that dialysis may be useful in selected severe poisoning.
• Coingestion of beta-blockers and CCBs or other antihypertensives can produce exceptionally refractory shock.

Investigations

Therapies at a Glance

Pharmacology

Prognosis / Complications

• Patients who receive early aggressive antidotal and hemodynamic support can recover fully because the myocardial dysfunction is pharmacologically reversible.
• Refractory shock, severe lactic acidosis, prolonged arrest, and multiorgan failure worsen prognosis.
• High-dose insulin can markedly improve cardiac output, but delayed initiation allows prolonged tissue hypoperfusion.
• Extended-release and long-half-life agents require longer observation because recurrent toxicity can occur after apparent stabilization.
• ECMO can bridge selected patients through the period of maximal toxicity when pharmacologic support is insufficient.
• Long-term prognosis after recovery is usually determined by hypoxic injury and complications rather than persistent cardiac dysfunction from the drug itself.

Patient Education / Counseling

• Store cardiovascular medications securely, particularly in homes with children or people at risk for intentional overdose.
• Do not take extra beta-blocker or CCB doses for a high home blood-pressure reading unless a clinician has specifically instructed that approach.
• After an accidental double dose, contact a poison center for agent-specific advice because extended-release products can have delayed effects.
• After intentional overdose, perform psychiatric assessment and address access to large medication supplies before discharge.
• Explain that recurrence of dizziness, fainting, slow pulse, weakness, or confusion after discharge from an exposure requires urgent reassessment.
• Review medication reconciliation carefully after recovery so essential cardiovascular therapy is restarted safely without recreating toxicity.

Notes

The modern treatment model is simultaneous rather than sequential. A profoundly hypotensive CCB patient should not wait through repeated ineffective atropine or isolated calcium doses before high-dose insulin and vasopressor support are started. Insulin, calcium, and vasoactive therapy address different components of the toxic physiology and are commonly used together.

The 2025 AHA special-circumstances guideline recommends high-dose insulin for hypotension in life-threatening CCB poisoning and for beta-blocker hypotension refractory to vasopressors. The accompanying antidote table lists a 1 unit/kg regular-insulin loading dose followed by 1 to 10 units/kg per hour, with protocolized surveillance for hypoglycemia, hypokalemia, and volume overload.

Extracorporeal therapy is drug specific. EXTRIP recommends against extracorporeal removal for severe poisoning from common CCBs such as amlodipine, diltiazem, and verapamil because they are poorly dialyzable. In contrast, selected beta-blockers including atenolol, nadolol, and sotalol may be sufficiently dialyzable for hemodialysis to contribute in severe cases. VA-ECMO is different from dialysis: it provides circulatory support and can bridge refractory cardiogenic shock while the toxin is metabolized or eliminated.

References

1. American Heart Association 2025 Special Circumstances of Resuscitation: Beta-Blocker and Calcium Channel Blocker Poisoning — Link
2. EXTRIP Workgroup Recommendations for Calcium Channel Blocker Poisoning — Link