What is the treatment for amlodipine (calcium channel blocker) poisoning?

Treatment of Amlodipine Poisoning

The treatment of amlodipine poisoning requires aggressive management with vasopressors and high-dose insulin therapy as first-line interventions, followed by calcium administration, with VA-ECMO reserved for refractory cases. 1, 2

Clinical Presentation of Amlodipine Toxicity

Amlodipine is a dihydropyridine calcium channel blocker (CCB) that primarily causes:

• Severe hypotension due to peripheral vasodilation
• Reflex tachycardia (unlike non-dihydropyridine CCBs)
• Altered mental status
• Pulmonary edema
• Metabolic acidosis and hyperglycemia
• QT prolongation and QRS widening in severe cases
• Cardiogenic shock in severe overdose 2

Treatment Algorithm

First-Line Interventions

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

   • Norepinephrine is preferred, starting at 2-10 mcg/min and titrating up to 100 μg/min as needed
   • Excellent survival rates with primary use of vasopressors have been demonstrated 1, 2

2. High-dose insulin therapy (Class 1, Level B-NR)

   • Bolus: 1 U/kg IV
   • Infusion: 0.5-1 U/kg/hour
   • Improves inotropy with lower rates of vasoconstrictive complications than vasopressor-only therapy
   • Requires close monitoring of glucose and potassium levels 1, 2

Second-Line Interventions

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

   • 10% calcium chloride or 10% calcium gluconate
   • Target ionized calcium concentrations up to twice normal
   • May improve heart rate, blood pressure, and conduction abnormalities 1, 2

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

   • For hemodynamically significant bradycardia
   • Dose: 0.5-1 mg IV, may repeat to maximum of 3 mg
   • Note: Treatment failures are common 1, 2

Refractory Cases

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

   • For persistent cardiogenic shock refractory to maximal pharmacological therapy
   • Reported survival rates up to 77% in CCB overdose 1, 2

2. Electrical pacing (Class 2b, Level C-LD)

   • For refractory bradyarrhythmias
   • May be ineffective in complete AV nodal blockade or vasodilatory shock 1

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

   • Bolus: 3-10 mg IV over 3-5 minutes
   • Infusion: 3-5 mg/hour
   • Response rates are variable; vomiting is common; rapid tachyphylaxis may occur 1, 2

4. Methylene blue

   • May be considered for refractory vasodilatory shock
   • Responses are mixed and effects may be transient 1

Important Considerations

• Avoid intravenous lipid emulsion (ILE) therapy (Class 3: No Benefit, Level C-LD)

  • Not recommended for routine use in CCB poisoning
  • May increase absorption of lipophilic drugs from the gastrointestinal tract 1

• Monitoring requirements:

  • Continuous cardiac monitoring
  • Frequent blood pressure measurements
  • Serial blood glucose and potassium levels
  • Ionized calcium levels
  • Acid-base status
  • Urine output 2

• Duration of treatment:

  • Amlodipine has a long half-life, requiring prolonged treatment
  • Patients may need extended clinical monitoring and supportive care 1, 2

Case-Based Evidence

Several case reports demonstrate successful management of severe amlodipine poisoning with combinations of the above therapies, including cases of ingestion of up to 150 mg 3, 4, 5. However, mortality remains high in severe cases, particularly when treatment is delayed or inadequate 5, 6, 7.

Pitfalls to Avoid

• Underestimating severity: Amlodipine has a long half-life and delayed onset of effects, requiring extended monitoring
• Inadequate fluid resuscitation: May lead to pulmonary edema, especially with large volume administration
• Delayed initiation of high-dose insulin: Should be started early in severe cases
• Relying solely on calcium: Most patients require multiple interventions
• Overlooking the need for VA-ECMO: Should be considered early for refractory shock