- CCBs are divided into 2 groups:
- Non-Dihydropyridines (Verapamil and Diltiazem) à cause a pup (heart) problem
- Dihydropyridines (Amlodipine, Felodipine, Nifedapine, Nimodipine and Lercanidipine)à cause a pipe (vasoplegic) problem
- However, in large overdoses receptor selectivity can be lost and the dihydropyridines can cause cariogenic shock.
- Ingestion of >10 tablets of verapamil or diltiazem XR can cause life-threatening toxicity.
- Effects are usually seen within 2 hours following standard preparations but can be delayed up to 16 hours with XR preparations.
- Early signs of toxicity includes a rising glucose (patients are in a drug induced hypoinsulinaemic state) and lactate.
- Typical signs include bradycardia, heart blocks and hypotension. If left untreated they can develop refractory shock and die.
Management of CCB overdose:
- As always, follow ABC. Intubate if the airway is compromised. However, it is important to remember to start at a 10th of your usual induction dose + push dose pressors prior to intubation if the patient is hypotensive
- High dose insulin is the antidote of choice. Early administration of High Dose Insulin 1unit/kg IV bolus and dextrose 50ml of 50% dextrose (paediatrics 5ml/kg of 10% dextrose to a max of 250ml). Followed by an infusion of insulin at 1 unit/kg/hour IV and a dextrose infusion. Some patients may not require additional dextrose early in the management. This will take 30-45 minutes to start working and therefore you will need other measures to manage the hypotension.
- Calcium gluconate and atropine. However, both of these agents are unlikely to work.
- A vasopressor such as norepinephrine will be the most effective. Start it peripherally until you get central access
- Ventricular pacing rarely works but in severe cases ECMO and intra-aortic ballon pump maybe considered.
- Charcoal to those who present within 1 hour of standard preparation or 4 hours for XR preparations. Whole bowel irrigation can be considered in patients who present within 4 hours of an XR preparation of 10 or more diltiazem or verapamil tablets.
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