Isofenphos poisoning: prolonged intoxication after intramuscular injection

We report a unique case of attempted suicide by intramuscular injection of the organophosphate isofenphos which resulted in a muscarinic and nicotinic syndrome lasting 15 days and requiring prolonged mechanical ventilation and hospitalization. The patient, who demonstrated no signs of delayed polyneuropathy on hospital day 25, subsequently died of pneumonia. Toxicological investigations showed isofenphos plasma decay and confirmed the intramuscular route of poisoning. We believe continuous isofenphos absorption resulted in the prolonged intoxication observed in this patient.