What is the treatment for a calcium channel blocker overdose?

Treatment of Calcium Channel Blocker Overdose

Immediately administer intravenous calcium as the first-line antidote, followed by high-dose insulin euglycemia therapy (HIET) for refractory shock, with escalation to ECMO for cases unresponsive to pharmacologic interventions. 1

Initial Resuscitation and Assessment

• Establish airway, breathing, and circulation following standard BLS/ACLS protocols 1, 2
• Place the patient on continuous cardiac monitoring with ECG to identify bradycardia, AV blocks, conduction delays, and dysrhythmias 1, 2
• Secure IV access immediately; use central venous access if prolonged therapy is anticipated 1, 2
• Obtain baseline labs: serum glucose, potassium, ionized calcium, and renal function 1, 2
• Consider activated charcoal (1-2 g/kg) if presentation is within 1-2 hours of ingestion and the airway is protected 2

Common pitfall: Many clinicians fail to recognize that patients may not have a perfusing blood pressure at presentation and delay initiating CPR 3. Always assess for adequate perfusion immediately.

First-Line Pharmacologic Therapy

Intravenous Calcium (Immediate Administration)

• Administer calcium immediately for catecholamine-refractory shock, as it directly counteracts calcium channel blockade 1, 2
• Dosing: 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 1
• Follow with continuous infusion of 0.3 mEq/kg per hour, titrated to hemodynamic response 1
• Monitor serum ionized calcium levels throughout; avoid severe hypercalcemia (>2× upper limit of normal) 1
• Atropine is only effective AFTER intravenous calcium has been administered 4

Critical caveat: Do not administer calcium in the setting of concomitant digoxin toxicity 5

High-Dose Insulin Euglycemia Therapy (HIET)

• HIET is the most effective therapy for restoring hemodynamic stability and improving survival in severe CCB toxicity 1, 2
• Initiate HIET for refractory shock when myocardial dysfunction persists despite calcium administration 1
• Initial bolus: 1 U/kg regular insulin IV with simultaneous 0.5 g/kg dextrose 1, 2
• Continuous infusion: 0.5-1 U/kg/hr insulin, titrated to clinical effect (can increase incrementally) 1, 2
• Dextrose infusion: 0.5 g/kg/hr, adjusted to maintain glucose 100-250 mg/dL 1
• The mechanism involves shifting to carbohydrate metabolism when insulin secretion is blocked by CCB effects on pancreatic islet cells 5

Second-Line Therapies

• Consider IV glucagon if first-line therapies fail, though evidence shows mixed results in both animal and human studies 1
• Atropine may be used for symptomatic bradycardia or conduction disturbances, but expect limited efficacy 1
• Temporary pacing for unstable bradycardia or high-grade AV block WITHOUT significant myocardial dysfunction 1
• Inotropic support with phosphodiesterase inhibitors or adrenergic agents is frequently required 5

Advanced Rescue Therapies

• Administer IV lipid emulsion for refractory shock or periarrest states 1
• Consider ECMO for shock refractory to all pharmacological interventions or cardiac arrest 1, 2
• Retrospective studies demonstrate improved outcomes in drug toxicity-related cardiac arrest with ECMO 1
• Consensus supports ECMO for reversible causes like CCB toxicity 1
• Levosimendan (a calcium sensitizer) may be considered in severe CCB poisoning when conventional therapy fails, as it improves contraction without increasing intracytosolic calcium 6

Cardiac Arrest Management

• Follow standard ACLS protocols with addition of IV calcium bolus 1
• Administer IV lipid emulsion therapy 1
• Deploy ECMO if available 1

Critical pitfall: The most commonly missed action is consulting cardiology or cardiothoracic surgery early for circulatory support options 3. Make this consultation promptly in severe cases.

Monitoring Parameters

• Continuous cardiac telemetry for rhythm and conduction abnormalities 1, 2
• Blood pressure monitoring with arterial line preferred for shock states 1, 2
• Serum glucose every 15 minutes initially during HIET titration, then hourly once stable 1, 2
• Serum potassium every 1-2 hours during HIET 1, 2
• Ionized calcium levels during calcium infusions 1, 2

Special Considerations by Agent

• Verapamil or diltiazem overdoses >300 mg carry significant risk of death; life-threatening arrhythmias occur at lower doses 4
• Slow-release verapamil requires prolonged treatment with intravenous calcium salts 4
• In high concentrations, all CCBs lose receptor specificity and can cause bradycardia, peripheral vasodilation, and hypotension regardless of class 3
• Patients may develop both vasoplegic shock from peripheral vasodilation and cardiogenic shock 3

Observation Periods

• Patients ingesting nonsustained-release products should be observed in a monitored setting for 12 hours 5
• Those ingesting sustained-release preparations require observation for no less than 24 hours 5

Strongly recommended: Consult a medical toxicologist or poison control center (1-800-222-1222) for all CCB overdoses to guide therapy and ensure access to advanced interventions 2