Prothiofos metabolites in human poisoning

A 63-year-old woman was admitted to a local hospital after the ingestion of 40% prothiofos preparation (Tokuthion) 370 mL. Gastric lavage was performed and cathartics, active charcoal, diuretics, atropine sulfate, and pralidoxime were administered. Serum cholinesterase activity was 1.3 IU/L (normal 200-460 IU/L). The patient's consciousness was gradually restored after 4 hours of charcoal hemoperfusion and she was discharged 5 days after admission with no sequelae.

Plasma and urine prothiofos and metabolites were detected by gas chromatography-flame photometry and gas chromatography-mass spectrometry. Two despropyl metabolites were synthesized for identification and estimation.

The main metabolites were identified with authentic prothiofos and methyl esters of synthesized des-S-propyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phosphate), despropyl prothiofos oxon (O-2,4-dichlorophenyl O-ethyl phospholothiolate), and des-S-propyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorothioate). Despropyl prothiofos (O-2,4-dichlorophenyl O-ethyl phosphorodithioate) was also identified in plasma. Large amounts of the hydrolyzed product, 2,4-dichlorophenol and its conjugate were also found. The metabolic pattern of prothiofos in humans appears to be different from that in rats.