Buckley N, Dawson A H, Howarth D, Whyte I M
Department of Clinical Pharmacology and Toxicology, Newcastle Mater Misericordiae Hospital, Waratah, NSW.
Med J Aust. 1993 Feb 1;158(3):202-4.
To present three cases of slow-release verapamil poisoning that demonstrate the prolonged absorption of the drug and the role of polyethylene glycol and high-dose calcium in management.
Three patients with slow-release verapamil poisoning are presented. An 18-year-old woman took 2.3 g and developed hypotension and bradyarrhythmias 18 hours after ingestion, despite gastric lavage and administration of charcoal at three hours. A 23-year-old woman took 4.8 g and presented two hours later clinically unaffected. A 44-year-old woman presented 24 hours after taking 15-20 g. She had a systolic blood pressure of 50 mmHg, no measurable diastolic blood pressure and bradyarrhythmias.
Case 1 responded to administration of 30 g of calcium and fluids intravenously. Case 2 was given polyethylene glycol on admission which resulted in passage of a tablet bezoar and no toxicity. Polyethylene glycol was ineffective in Case 3. She responded initially to high doses of calcium and other treatments, but subsequently died of hypotension and cardiac conduction block 39 hours after the overdose.
The severity of poisoning with slow-release verapamil warrants aggressive pre-emptive treatment. Polyethylene glycol should be used routinely irrespective of the clinical state. High doses of calcium may be required to treat conduction block and hypotension.
