Intermediate syndrome after malathion ingestion despite continuous infusion of pralidoxime

Case Report: A 33-year-old female ingested an unknown quantity of malathion in a suicide attempt. Cholinergic signs consistent with severe organophosp hate intoxication developed and were treated within 6 hours of ingestion. I ntravenous atropine and a continuous infusion of pralidoxime (400 mg/h) wer e administered. Prolonged depression of plasma and red blood cell cholinest erases were documented. Despite an initial clinical improvement and the pre sence of plasma pralidoxime concentrations exceeding 4 mu g/mL, the patient developed profound motor paralysis consistent with the diagnosis of Interm ediate Syndrome. In addition to the dose and frequency of pralidoxime admin istration, other factors including persistence of organophosphate in the bo dy, the chemical structure of the ingested organophosphate, and the time el apsed between ingestion and treatment may limit the effectiveness of pralid oxime as an antidote in organophosphate ingestions. This case study suggest s that these factors should be taken into account in assessing the risk of Intermediate Syndrome after intentional organophosphate ingestions.