What is the immediate antidotal treatment for a calcium‑channel‑blocker overdose?

Antidote for Calcium Channel Blocker Overdose

For immediate antidotal treatment of calcium channel blocker overdose, administer IV calcium as the first-line antidote, followed immediately by high-dose insulin euglycemia therapy (HIET), with vasopressors (norepinephrine/epinephrine) for hemodynamic support. 1, 2

First-Line Antidotal Therapies (Initiate Simultaneously)

IV Calcium

• Administer 0.3 mEq/kg (0.6 mL/kg of 10% calcium gluconate OR 0.2 mL/kg of 10% calcium chloride) IV over 5-10 minutes 2
• Follow with continuous infusion of 0.3 mEq/kg per hour, titrated to hemodynamic response 2
• Target ionized calcium levels up to twice normal, but avoid severe hypercalcemia (>2× upper limit) 1, 2
• While calcium is recommended first-line, most patients require additional treatments beyond calcium monotherapy 1

High-Dose Insulin Euglycemia Therapy (HIET)

• Initiate early—HIET is most effective when started in the intoxication phase, even before significant hemodynamic instability develops 3
• Give 1 U/kg regular insulin IV bolus with 0.5 g/kg dextrose 2
• Start continuous infusion at 0.5-1 U/kg/hr insulin with 0.5 g/kg/hr dextrose 2
• Titrate insulin incrementally up to 10 U/kg/hr based on clinical response 1, 2
• Monitor glucose every 15 minutes initially, then hourly once stable; maintain glucose 100-250 mg/dL 2
• Monitor potassium every 1-2 hours and supplement as needed (insulin drives potassium intracellularly) 2
• HIET improves cardiac inotropy, facilitates myocardial carbohydrate utilization, and has shown favorable outcomes with lower vasoconstrictive complications than vasopressor-only therapy 1

Vasopressor Support

• Norepinephrine and/or epinephrine are recommended first-line for hemodynamic support 1
• Large retrospective series demonstrate excellent survival with vasopressors (norepinephrine up to 100 μg/min in adults) with low ischemic complication rates 1
• Consider dobutamine or epinephrine specifically for cardiogenic shock 1
• Atropine may be attempted for symptomatic bradycardia but has limited efficacy 1

Second-Line Therapies for Refractory Cases

Escalate HIET

• Increase insulin infusion incrementally up to 10 U/kg/hr if myocardial dysfunction persists 1, 2
• Continue aggressive dextrose supplementation to maintain euglycemia 1

Intravenous Lipid Emulsion (ILE)

• The 2023 American Heart Association guidelines recommend AGAINST routine use of ILE for CCB poisoning 1
• Reserve ILE only for refractory shock or periarrest states unresponsive to other therapies 1, 2
• Evidence shows ILE may increase gastrointestinal absorption of oral CCB overdoses, potentially worsening toxicity 1
• If used: 1.5 mL/kg of 20% lipid emulsion bolus, repeat up to twice, followed by 0.25 mL/kg/min infusion for 30-60 minutes 1
• Maximum dose: 12.5 mL/kg per 24 hours 1

Temporary Cardiac Pacing

• Consider for unstable bradycardia or high-grade AV block WITHOUT significant myocardial dysfunction 1, 2
• Try transcutaneous pacing first; if effective, proceed to transvenous pacing 1
• Results are mixed—pacing may not be effective in complete AV nodal blockade or vasodilatory shock 1

Glucagon

• Evidence for glucagon is inconsistent with variable response rates 1, 3
• Vomiting is common and rapid tachyphylaxis may occur 1
• The 2023 AHA guidelines state the usefulness is uncertain 1

Rescue Therapies for Refractory Shock/Periarrest

VA-ECMO (Venoarterial Extracorporeal Membrane Oxygenation)

• Strongly consider VA-ECMO for refractory cardiogenic shock unresponsive to maximal pharmacologic therapy 1, 2
• Case series report survival rates as high as 77% with VA-ECMO in CCB overdose 1
• VA-ECMO is particularly effective when pump failure (cardiogenic component) predominates 1, 2

Cardiac Arrest Management

• Administer IV calcium bolus in addition to standard ACLS protocols 1, 2
• Give IV lipid emulsion therapy during cardiac arrest 1, 2
• Deploy VA-ECMO if available 1, 2

Critical Monitoring Parameters

• Continuous cardiac telemetry for rhythm and conduction abnormalities 2
• Arterial line for continuous blood pressure monitoring in shock states 2
• Serum glucose every 15 minutes during HIET titration, then hourly 2
• Serum potassium every 1-2 hours during HIET 2
• Ionized calcium levels during calcium infusions 2

Common Pitfalls to Avoid

• Do not delay HIET initiation—it is most effective when started early, even before severe hemodynamic compromise 3
• Do not use ILE routinely—reserve for refractory cases only, as it may worsen oral overdoses 1
• Do not rely on calcium monotherapy alone—most patients require multimodal therapy 1
• Do not attempt electrical pacing in patients with significant myocardial dysfunction—it will likely be ineffective 1
• Avoid hypoglycemia during HIET by maintaining aggressive glucose monitoring and dextrose supplementation 2
• Watch for hypokalemia and volume overload during HIET 1