Calcium Channel Blocker Overdose

All calcium channel blockers can cause arteriolar vasodilation and depression of cardiac contractility after acute overdose

Examples of calcium channel blockers

• Verapamil

• Diltiazem

• Nifedipine

• Nicardipine

• Amlodipine

• Felodipine

• Isradipine

• Nisoldipine

• Nimodipine

Bradycardia, atrioventricular (AV) nodal block, hypotension, or a combination

With severe poisoning, cardiac arrest may occur

Clinical

Junctional bradycardia is common, with even moderate verapamil or diltiazem poisoning

Activated charcoal

• Give 60–100 g mixed in aqueous slurry orally or via gastric tube

• Do not use for comatose or convulsing patients unless they are endotracheally intubated

Perform whole-bowel irrigation as soon as possible if a sustained-release product has been ingested

Treat hypotension and bradycardia with calcium chloride intravenously

• Start with 10%, 10 mL, or calcium gluconate, 20 mL; repeat the dose every 3–5 minutes

• Maximum dose has not been established

• Many toxicologists recommend raising the ionized serum calcium level to as much as twice the normal level

• Calcium is most useful in reversing negative inotropic effects

• It is less effective for AV nodal blockade and bradycardia

High doses of insulin 0.5–1.0 units/kg bolus followed by 0.5–1.0 units/kg/h infusion with sufficient dextrose to maintain euglycemia may be beneficial

Infusion of Intralipid 20% lipid emulsion has been reported to improve hemodynamics in animal models and case reports of calcium channel poisoning

Methylene blue (1–2 mg/kg) was reported to reverse refractory shock due to profound vasodilation in a patient with amlodipine poisoning