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 while simultaneously initiating high-dose insulin euglycemia therapy (HIET) for any patient with hemodynamic instability from calcium channel blocker overdose. 1

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 1
• 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
• Recognize that severe overdoses can cause both vasoplegic shock from peripheral vasodilation and cardiogenic shock, regardless of whether the agent is a dihydropyridine or non-dihydropyridine CCB 2

First-Line Pharmacologic Therapy

Intravenous Calcium (Immediate Administration)

Administer calcium immediately for catecholamine-refractory shock as the initial antidote. 1

• Bolus dose: 0.3 mEq/kg (equivalent to 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
• Monitor serum ionized calcium levels throughout treatment and avoid severe hypercalcemia exceeding 2× the upper limit of normal 1
• Calcium has proven efficacy in reversing depression of cardiac conduction and increasing blood pressure in CCB overdose 3

High-Dose Insulin Euglycemia Therapy (HIET)

Initiate HIET early for refractory shock and escalate if myocardial dysfunction persists. 1, 4

• Initial bolus: 1 U/kg regular insulin with 0.5 g/kg dextrose 1, 4
• Continuous insulin infusion: 0.5-1 U/kg/hr, titrated to clinical effect (can increase incrementally as needed) 1, 4
• Dextrose infusion: 0.5 g/kg/hr, adjusted to maintain glucose 100-250 mg/dL 1
• Glucose monitoring: Every 15 minutes initially during titration phase, then hourly once stable 1
• Potassium monitoring: Every 1-2 hours during HIET to prevent hypokalemia 1
• HIET works through a direct positive inotropic effect on myocardial contractility 4

Second-Line Therapies

Vasopressors and Inotropes

• Dopamine has demonstrated efficacy in increasing blood pressure in CCB overdose and should be used for persistent hypotension 3
• Consider IV glucagon if first-line therapies fail, though evidence shows mixed results in both animal and human studies 1

Bradycardia Management

• Atropine may be attempted for symptomatic bradycardia or conduction disturbances, but expect limited efficacy (only 25% response rate in clinical studies) 1, 3
• Use temporary pacing for unstable bradycardia or high-grade AV block WITHOUT significant myocardial dysfunction 1
• Note that AV nodal depression is more common with verapamil overdoses compared to other CCBs 3

Advanced Rescue Therapies for Refractory Shock

Lipid Emulsion Therapy

• Administer IV lipid emulsion for refractory shock or periarrest states 1

Extracorporeal Membrane Oxygenation (ECMO)

Consider ECMO for refractory shock with significant cardiogenic component or cardiac arrest. 1

• Retrospective studies show improved outcomes in drug toxicity-related cardiac arrest with ECMO 1
• Consensus supports ECMO for reversible causes like CCB toxicity 1
• Consult cardiology or cardiothoracic surgery early for circulatory support options in severe cases 2

Novel Therapies

• Levosimendan, a calcium sensitizer, may be considered in severe CCB poisoning when conventional therapies fail, as it improves contraction without increasing intracytosolic calcium concentration 5
• Resin hemoadsorption/hemoperfusion using styrene resin filters has shown promise in case reports for enhanced drug clearance, though this remains experimental 6

Cardiac Arrest Management

• Follow standard ACLS protocols with the addition of IV calcium bolus 1
• Consider IV lipid emulsion therapy for cardiac arrest 1
• Consider ECMO if available for cardiac arrest 1

Critical Monitoring Parameters

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

Common Pitfalls to Avoid

• Do not delay HIET initiation—it has become the mainstay of treatment in severe CCB overdose 7
• Do not assume a patient has a perfusing blood pressure without verification; start CPR if pulseless 2
• Do not overlook that high-concentration CCB overdoses lose receptor specificity, causing both bradycardia and peripheral vasodilation regardless of CCB subtype 2
• Do not rely solely on atropine for bradycardia, as it has poor efficacy in CCB toxicity 1, 3