What is the management for an amlodipine (calcium channel blocker) overdose?

Management of Amlodipine Overdose

High-dose insulin therapy combined with vasopressors and calcium administration forms the cornerstone of management for severe amlodipine overdose with hemodynamic instability. 1

Initial Assessment and Stabilization

• Vital Signs Monitoring: Continuous cardiac monitoring, frequent blood pressure measurements, and respiratory assessment
• Clinical Presentation: Look for hypotension, bradycardia (more common with non-dihydropyridines), reflex tachycardia, altered mental status, and pulmonary edema
• Laboratory Tests: Obtain electrolytes, renal function, blood glucose, ionized calcium levels, and arterial blood gases

Treatment Algorithm

Step 1: Decontamination (if early presentation)

• Activated charcoal if within 1-2 hours of ingestion
• Consider whole bowel irrigation for sustained-release formulations

Step 2: Hemodynamic Support

1. IV Fluid Resuscitation

   • Judicious fluid administration (caution with volume overload risk)

2. Vasopressors (Class 1, Level B-NR) 1

   • Norepinephrine (first-line): Start at 2-10 mcg/min, titrate up to 100 μg/min as needed
   • Consider adding vasopressin or epinephrine for refractory hypotension

3. Calcium Administration (Class 2a, Level C-LD) 1

   • 10% Calcium chloride: 1-2 g IV every 10-20 min or infusion at 0.2-0.4 mL/kg/h
   • OR 10% Calcium gluconate: 3-6 g IV every 10-20 min or infusion at 0.6-1.2 mL/kg/h
   • Target ionized calcium concentrations up to twice normal

Step 3: High-Dose Insulin Euglycemia Therapy (HIET) (Class 2, Level B-NR) 1

• Regular insulin: 1 U/kg IV bolus followed by infusion at 0.5-1 U/kg/hour
• Dextrose: 0.5 g/kg bolus followed by infusion at 0.5 g/kg/hour
• Monitoring: Check glucose every 15-30 minutes initially, then hourly
• Titration: May increase insulin up to 10 U/kg/hour in refractory cases 2
• Cautions: Monitor for hypoglycemia, hypokalemia, and fluid overload

Step 4: Additional Therapies for Refractory Cases

1. Atropine (Class 2a, Level C-LD) 1

   • For symptomatic bradycardia: 0.5-1 mg IV, may repeat to maximum of 3 mg

2. Glucagon (Class 2b, Level C-LD) 1

   • 3-10 mg IV bolus over 3-5 minutes, followed by infusion of 3-5 mg/hour
   • Caution: May cause vomiting (protect airway)

3. Methylene Blue (for vasodilatory shock) 1

   • 1-2 mg/kg IV over 15-30 minutes
   • May provide transient benefit in refractory vasodilatory shock

4. VA-ECMO (Class 2a, Level C-LD) 1

   • Consider for refractory cardiogenic shock despite maximal pharmacological therapy
   • Reported survival rates up to 77% in CCB overdose

5. Electrical Pacing (Class 2b, Level C-LD) 1

   • For refractory bradyarrhythmias
   • Note: Often ineffective in complete AV nodal blockade or vasodilatory shock

Special Considerations

• Avoid Intravenous Lipid Emulsion (ILE): Not recommended for routine use in CCB poisoning (Class 3: No Benefit, Level C-LD) 1

• Hemodialysis: Unlikely to be beneficial as amlodipine is highly protein-bound 3

• Monitoring Duration: Extended monitoring is necessary due to amlodipine's long half-life (30-50 hours) and delayed peak effects 4

Pitfalls and Caveats

1. Delayed Toxicity: Amlodipine has a long half-life; patients may deteriorate hours after ingestion

2. Volume Overload: Aggressive fluid resuscitation may precipitate pulmonary edema 4

3. Insulin Therapy Management:

   • Requires close glucose monitoring
   • Hypokalemia is a common complication
   • Effect may be dose-dependent; consider higher doses in refractory cases 2

4. Combination Overdoses: Be alert for co-ingestions, especially with beta-blockers, which can worsen cardiac depression 5

5. Refractory Cases: Early consideration of ECMO is critical as mortality remains high in severe cases despite maximal therapy 6