What is the treatment for a calcium channel blocker overdose?

Treatment of Calcium Channel Blocker Overdose

Immediately administer IV calcium as the first-line antidote while simultaneously initiating high-dose insulin euglycemia therapy (HIET) for any patient with calcium channel blocker overdose presenting with shock or significant hemodynamic instability. 1, 2

Initial Resuscitation and Assessment

• Establish airway, breathing, and circulation following standard BLS/ACLS protocols 1
• Place the patient on continuous cardiac monitoring with ECG to identify bradycardia, AV blocks, and dysrhythmias—note that AV nodal depression occurs more commonly with verapamil than dihydropyridines 1, 3
• Secure IV access, preferably central venous access if prolonged therapy is anticipated 1
• Obtain baseline labs immediately: serum glucose, potassium, ionized calcium, and renal function 1

Common pitfall: Many clinicians fail to recognize that patients may not have a perfusing blood pressure at presentation and delay CPR initiation 4

First-Line Pharmacologic Therapy

Calcium Administration

Administer calcium immediately for catecholamine-refractory shock: 1

• 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
• Continuous infusion: 0.3 mEq/kg per hour, titrated to hemodynamic response 1
• Monitoring: Check serum ionized calcium levels and avoid severe hypercalcemia (>2× upper limit of normal) 1
• Evidence: Calcium is efficacious in reversing depression of cardiac conduction and increasing blood pressure in CCB overdose 3

High-Dose Insulin Euglycemia Therapy (HIET)

Initiate HIET concurrently with calcium for refractory shock—this is a first-line treatment, not a second-line option: 1, 2

• Initial bolus: 1 U/kg regular insulin with 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
• Mechanism: HIET has a direct positive inotropic effect on myocardial contractility 2
• Critical monitoring: Check glucose every 15 minutes initially during titration, then hourly once stable 1
• Potassium monitoring: Check every 1-2 hours during HIET as insulin drives potassium intracellularly 1

Second-Line Therapies

• Glucagon: Consider if first-line therapies fail, though evidence is inconsistent with mixed results in both animal and human studies 1
• Atropine: Use for symptomatic bradycardia or conduction disturbances, but expect limited efficacy—only 2 of 8 patients responded in one series 1, 3
• Temporary pacing: Use for unstable bradycardia or high-grade AV block WITHOUT significant myocardial dysfunction 1
• Vasopressors: Dopamine was efficacious in increasing blood pressure in 10 patients in one case series 3

Important distinction: Non-dihydropyridine CCBs (verapamil, diltiazem) cause more cardiac manifestations including bradycardia and negative inotropy, while dihydropyridines (amlodipine, nifedipine) cause more peripheral vasodilation—but at high concentrations in overdose, all CCBs lose specificity and can cause both vasoplegic and cardiogenic shock 4

Advanced Rescue Therapies

For refractory shock despite maximal medical therapy: 1

• Lipid emulsion: Administer for refractory shock or periarrest states 1
• ECMO: Consider for refractory shock with significant cardiogenic component or cardiac arrest—retrospective studies show improved outcomes in drug toxicity-related cardiac arrest, and consensus supports ECMO for reversible causes like CCB toxicity 1
• Hemoadsorption/hemoperfusion: Emerging evidence suggests styrene resin hemoperfusion may enhance amlodipine clearance and resolve hemodynamic instability, though this requires specialized equipment 5
• Levosimendan: This calcium sensitizer has been reported to improve hemodynamics in severe CCB poisoning when conventional therapy fails, as it improves contraction without increasing intracytosolic calcium 6

Critical action often missed: Consult cardiology or cardiothoracic surgery early for circulatory support options (ECMO, mechanical support) in severe cases 4

Cardiac Arrest Management

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

Continuous Monitoring Parameters

• Cardiac telemetry: Continuous monitoring for rhythm and conduction abnormalities 1
• Blood pressure: Arterial line preferred for shock states 1
• Glucose: Every 15 minutes initially, then hourly once stable 1
• Potassium: Every 1-2 hours during HIET 1
• Ionized calcium: During calcium infusions 1

Key pitfall: Do not overlook potential co-ingestants that may complicate management, as polypharmacy overdoses are common 7