Unintentional fatal overdose of veterinary levamisole in a human subject

Cases of levamisole overdose without coingestants in human subjects are rare. Existing knowledge of human toxicity depends in part on records of adverse events of therapeutic use such as nausea, vomiting, headache, and rarer central nervous system effects. Much of our knowledge also comes from levamisole's role as an adulterant in cocaine, where it is known to have immune modulatory properties and is associated with vasculitis. The few cases of levamisole-only toxicity are either non-fatal or lack clinical details. We present the first case of a fatal, oral ingestion of levamisole in a patient who presented alive with clinical symptoms and had treatment documented. The patient's early symptoms included nausea, vomiting, tremors, and visual changes. Following this, the patient experienced bradycardia followed by pulseless electrical activity cardiac arrest. This presentation was consistent with what would be expected of the pharmacodynamic effects of levamisole as a nicotinic agonist. Levamisole's presence was confirmed by post-mortem confirmatory testing, with a recorded femoral blood concentration of 19,000 ng/mL. The clinical picture and post-mortem testing were consistent with the cause of death as levamisole overdose.