Massive overdose of sustained-release verapamil: a case report and review of literature.

Verapamil 99 is a commonly prescribed medicine for treatment of hypertension, angina, and migraine headache. Toxicity with sustained-release verapamil may be prolonged, and manifest with hypotension, bradycardia, metabolic acidosis, and hyperglycemia. Currently, because of the lack of a specific antidote management of verapamil, toxicity is mainly supportive. Treatment with inotropic support, glucagon, calcium, and cardiac pacing may be effective in some cases. A review of 20 cases and a case report of sustained-release verapamil overdose are described. The authors describe a patient who ingested 24 g of slow-release verapamil. This is the largest overdose of sustained-release verapamil reported in English literature. The patient was managed aggressively with gastric lavage, inotropic support, and continuous infusion of calcium and glucagon. The patient's survival may have been due to the continuous intravenous calcium gluconate and glucagon infusion. Both of these treatment modalities should be considered in patients with moderate to severe calcium channel blocker overdose.