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

Treatment of Amlodipine Poisoning

For amlodipine poisoning causing hypotension or shock, immediately administer vasopressors (particularly norepinephrine) and high-dose insulin therapy as first-line treatments, with calcium as an adjunct, and consider VA-ECMO for refractory cardiogenic shock. 1, 2

First-Line Pharmacologic Management

Vasopressors (Class 1 Recommendation)

• Norepinephrine is the most commonly used vasopressor, with doses up to 100 μg/min in adults demonstrating excellent survival rates and low rates of ischemic complications. 1
• Vasopressors should be initiated immediately for hypotension, as they are readily available and act quickly. 1
• There is no evidence to guide the choice of specific vasopressor, but norepinephrine has the strongest supporting data. 1

High-Dose Insulin Therapy (Class 1 Recommendation)

• High-dose insulin administration improves inotropy in severe cardiogenic shock from calcium channel blocker poisoning and should be given for hypotension refractory to or in conjunction with vasopressors. 1, 2
• This therapy has demonstrated favorable outcomes with lower rates of vasoconstrictive complications compared to vasopressor-only therapy. 1
• Survival has been reported even after cardiac arrest. 1
• Critical monitoring required: Protocolized care is essential to reduce hypoglycemia risk; hypokalemia and volume overload are additional concerns that must be monitored. 1

Calcium Therapy (Class 2a Recommendation)

• Administer calcium (calcium gluconate or calcium chloride) for improvements in heart rate, blood pressure, and conduction abnormalities. 1, 2
• High doses targeting ionized calcium concentrations up to twice normal appear more effective than lower doses. 1
• Important caveat: Most patients require additional treatments beyond calcium alone; it should not be used as monotherapy. 1

Management of Bradycardia

Atropine (Class 2a Recommendation)

• Atropine is reasonable for hemodynamically significant bradycardia from amlodipine poisoning, though treatment failures are reported. 1
• Commonly used as first-line therapy but should not be relied upon as sole treatment. 1

Electrical Pacing (Class 2b Recommendation)

• Electrical pacing may be reasonable for hemodynamically significant bradydysrhythmias, but results are mixed. 1
• Pitfall: Pacing is not always effective, particularly in patients with complete atrioventricular nodal blockade or vasodilatory shock (which is common with amlodipine as a dihydropyridine). 1

Advanced Life Support

VA-ECMO (Class 2a Recommendation)

• For refractory cardiogenic shock despite maximal pharmacological support, VA-ECMO may be lifesaving with reported survival rates as high as 77%. 1, 2
• ECMO should be considered early in patients with persistent pump failure refractory to vasopressors and high-dose insulin. 1, 2
• Case reports demonstrate successful bridging to recovery with ECMO support in severe amlodipine toxicity. 3

Adjunctive Therapies with Limited Evidence

Glucagon (Class 2b Recommendation)

• The usefulness of glucagon bolus and infusion for calcium channel blocker poisoning is uncertain. 1
• Response rates are variable, vomiting is common, and rapid tachyphylaxis may occur. 1

Methylene Blue

• Methylene blue may be considered as an adjunct for refractory vasodilatory shock specifically after amlodipine overdose (as a dihydropyridine causing prominent vasodilation). 1
• Responses are mixed and effects may be transient. 1

Treatments NOT Recommended

Intravenous Lipid Emulsion (Class 3: No Benefit)

• Do NOT routinely use intravenous lipid emulsion therapy for calcium channel blocker poisoning. 1, 2
• Clinical and experimental data suggest ILE increases absorption of lipophilic drugs (like amlodipine) from the gastrointestinal tract, potentially worsening oral overdose. 1, 2
• Whether there is a role for ILE in patients who have failed other modalities and are in cardiac arrest or periarrest remains uncertain. 1

Clinical Presentation and Monitoring

Expected Toxicity Profile

• Amlodipine, as a dihydropyridine calcium channel blocker, primarily causes peripheral vasodilation and vasodilatory shock at toxic doses. 1
• Prolonged hypotension lasting several days is common due to amlodipine's long half-life. 2
• Patients may develop severe cardiovascular collapse, non-cardiogenic pulmonary edema, and metabolic acidosis. 4, 5

Critical Monitoring Parameters

• Continuous blood pressure and heart rate monitoring is essential. 2
• Monitor for hypoglycemia, hypokalemia, and volume overload during high-dose insulin therapy. 1
• Serial ionized calcium levels if using high-dose calcium therapy. 1

Important Clinical Pitfalls

• Amlodipine toxicity can present with recurrent episodes of vasodilatory shock even after initial stabilization. 4
• Small doses (0.9 to 4.1 mg/kg) may produce rapid and fatal cardiovascular collapse, particularly in children. 5
• The combination of amlodipine with other cardiovascular drugs (e.g., beta-blockers, ACE inhibitors) significantly worsens toxicity and requires more aggressive management. 6
• Delayed presentation (hours after ingestion) does not preclude severe toxicity due to sustained-release formulations and long half-life. 2, 7