Toxicology: Calcium Channel Blockers

Calcium channel blocker ingestions can cause profound bradycardia, hypotension, conduction abnormalities, and shock, and even a single tablet can be dangerous in a young child. In this episode of PEM Currents, we review the recognition and management of pediatric calcium channel blocker toxicity, including differences between dihydropyridine and non-dihydropyridine agents, high-dose insulin therapy, calcium and vasopressor support, and when to consider VA-ECMO.

Learning Objectives

After listening to this episode, learners should be able to:

1. Recognize the clinical manifestations of calcium channel blocker toxicity and distinguish the typical effects of dihydropyridine and non-dihydropyridine agents.
2. Describe the initial evaluation and management of a child with suspected calcium channel blocker toxicity, including the roles of calcium, atropine, high-dose insulin therapy, and vasopressors.
3. Identify children who require prolonged observation, ICU admission, or escalation to advanced therapies such as VA-ECMO.

References

1. Management of calcium channel blocker toxicity in the pediatric patient. J Pediatr Pharmacol Ther. 2019;24(5):378-386.
2. Are one or two dangerous? Calcium channel blocker exposure in toddlers. J Emerg Med. 2007.
3. Intravenous lipid emulsion treatment for calcium-channel blocker intoxication: pediatric case series and review of the literature. Pediatr Emerg Care. 2022.
4. Audette M, Comstock G. Is beta blocker toxicity associated with hypoglycemia? J Med Toxicol. 2026;22(3):357-363. doi:10.1007/s13181-026-01134-8.

Script

This is the original script for the episode, written by Drs. Robbie Daulton and Brad Sobolewski

1. Why CCBs Are So Dangerous

Calcium channel blockers are an increasingly prescribed drug class which includes amlodipine, verapamil, diltiazem, and nifedipine. Unlike some of the ingestions we cover in this series, there’s no single reliably curative reversal agent. For non-dihydropyridine agents like verapamil and diltiazem especially, a single adult tablet can be lethal to a toddler; that’s exactly why they sit on the “one pill can kill” list. The sleepy, bradycardic toddler with altered mental status can look like sepsis or a metabolic problem well before it looks like a toxic ingestion, which is why this presentation is a challenge to identify.

2. How Kids Present

The presentation depends heavily on which calcium channel blocker we’re talking about. Nausea and vomiting are the most common early complaint across all of these agents, so don’t be reassured by a benign-sounding chief complaint.

Dihydropyridines, think amlodipine and nifedipine, are selective for vascular smooth muscle at therapeutic doses, so they mostly cause peripheral vasodilation and reflex tachycardia. But in overdose, that selectivity is lost, meaning you can see cardiogenic or distributive shock.

Non-dihydropyridines, verapamil and diltiazem, hit the heart directly, meaning they can cause primarily cardiogenic shock. They slow the sinus node and block AV conduction, leading to sinus bradycardia, first-degree or higher-grade AV block, and sometimes a junctional escape rhythm, with a QRS that usually stays narrow since CCBs spare intraventricular conduction.

3. Pharmacology Pearls

Calcium channel blockade doesn’t stop at the heart and vessels. These L-type channels also exist on pancreatic beta cells. Blockade suppresses insulin secretion and worsens peripheral insulin resistance. Cardiac myocytes become relatively starved of a key fuel during this stress state. High-dose exogenous insulin restores myocardial glucose uptake and improves contractility, aiding in cardiogenic shock states.

4. Work Up and Treatment

Remember, if you have a child who presents with concerns for a CCB, it is important to urgently contact the Poison Control Center.

Start with the fundamentals