Abstract
The toxicokinetics of methyl paraoxon, the active metabolite of the organophosphorus insecticide methyl parathion, were studied in non-anaesthetized dogs after intravenous (2.5 mg/kg) and oral (15 mg/kg) administration of methyl paraoxon. After intravenous administration, distribution and elimination occured very rapidly and using the data from 5 min post-injection, the plasma concentration versus time curves could be fitted to a one-compartment open model. The mean half-life of elimination was 9.7 min, the average volume of distribution 1.76 l/kg and the average plasma clearance 126 ml/kg/min. After oral administration, peak plasma concentrations were obtained within 3–16 min, and the bioavailability varied from 5 to 71%. The hepatic extraction of methyl paraoxon measured in anaesthetized dogs, was high (70–92%). Comparison of the urinary excretion after intravenous and oral administration in two dogs indicated a gastrointestinal absorption of more than 60%. The kinetics of methyl paraoxon were linear in the dose range tested.
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De Schryver, E., De Reu, L., Belpaire, F. et al. Toxicokinetics of methyl paraoxon in the dog. Arch Toxicol 59, 319–322 (1987). https://doi.org/10.1007/BF00295082
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DOI: https://doi.org/10.1007/BF00295082