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Calcium Channel Blocker Overdose

Calcium Channel Blocker Overdose

Verapamil / Diltiazem

Most toxic- Toxicity can occur at 2-3 x normal dose in children and the elderly

Amlodipine / Nifedipine / Felodipine / Lercanidipine / Nimodipine

Rapid absorption

Standard release presentations cause symptoms within 1-2 hours

Beware slow(modified) release preparations as effects can occur up to 12 hours later

They affect myocardial contractility and slow conduction through SAN and AVN.

  • Antagonize extracellular Ca2+ into cardiac muscle
    • Affect O phase depolarization in SAN, AVN.
  • Antagonize extracellular Ca2+ Into smooth muscle
    • Decreased smooth muscle contraction = vasodilation

How do Patient’s Present?

CardiovascularGITMetabolicCNS (may be late)
Hypotension (Vasoplegia)Nausea and VomitingHyperglycaemiaConfusion
ArrhythmiasMetabolic AcidosisSlurred Speech
2nd/3rd degree AV Block
Sinus Arrest/Asystole
Pulmonary Oedema


Decontamination: Activated Charcoal 50g if alert and:

  • Standard Release
    • < 2hours post ingestion
  • Modified Release
    • < 6hours of Amlodipine / Nifedipine / Felodipine / Lercanidipine / Nimodipine
    • < 12 hours of Verapamil / Diltiazem


  • Atropine: 0.6mg (paeds 0.02mg/kg) IV x 3 doses q 5min
  • Pacing


  • Fluids: 10-20mL/kg crystalloid- beware as too much fluid can cause pulmonary oedema.
  • Pressors: Noradrenaline as first line agent, unless bradycardia, then Adrenaline can be used. If using Noradrenaline and not effective can add Vasopressin
  • Calcium: 30 mL Ca gluconate 10% (3 grams, 6.6 mmol) IV over 10 minutes x 3 in 60 minutes. Then Ca infusion to maintain ionized Ca2+ concentration 1.5 – 2.0 mmol/L
  • High Dose Insulin Euglycaemic Therapy (Discuss with Toxicology)
    • Actrapid 1u/kg IV then infusion +50 ml of 50% dext then infusion
    • Sodium Bicarbonate: 1-2 mmol/kg 3-5 min to PH >7.3
  • Methylene Blue / Lipid Emulsion in refractory shock (Discuss with Toxicology)
  • ECMO if hypotension is refractory to all treatments