Repetitive obidoxime treatment induced increase of red blood cell acetylcholinesterase activity even in a late phase of a severe methamidophos poisoning: A case report

Toxicol Lett. 2016 Feb 26:244:121-123. doi: 10.1016/j.toxlet.2015.07.010. Epub 2015 Jul 19.

Abstract

Accidental self-poisoning or deliberate use in suicidal intent of organophosphorus pesticides (OPP), which are widely used in agriculture, represent a health problem worldwide. Symptoms of poisoning are characterized by acute cholinergic crisis caused by inhibition of acetylcholinesterase. A 75-year-old male patient ingested 20ml of an OPP solution containing 10% methamidophos in suicidal intent. In the course of poisoning typical clinical symptoms of cholinergic crisis (miosis, bradycardia, hypotension, hypersalivation and impairment of neurologic status) were evident. Butyryl (plasma) cholinesterase (BChE) and red blood cell acetylcholinesterase (RBC-AChE) revealed decreased activities, thus specific treatment with the enzyme reactivator obidoxime was started. Inhibitory activity of the patient's plasma indicated significant amounts of persisting methamidophos in the circulation and was still found on day 4 after ingestion. Due to missing spontaneous breathing on day 6, obidoxime was administered again. Afterwards a significant increase of RBC-AChE activity was found. The patient was extubated on day 10 and a restitution ad integrum was achieved. In conclusion, obidoxime is a potent reactivator of OPP-inhibited AChE. A repetitive and prolonged administration of obidoxime should be considered in cases of severe methamidophos poisoning and should be tailored with an advanced analytical biomonitoring.

Keywords: Intoxication; Methamidophos; Organophosphorus compounds; Red blood cell acetylcholinesterase; obidoxime.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Acetylcholinesterase / blood*
  • Aged
  • Antidotes / administration & dosage*
  • Biomarkers / blood
  • Cholinesterase Inhibitors / poisoning*
  • Cholinesterase Reactivators / administration & dosage*
  • Drug Administration Schedule
  • Erythrocytes / drug effects*
  • Erythrocytes / enzymology
  • GPI-Linked Proteins / blood
  • Humans
  • Insecticides / poisoning*
  • Male
  • Obidoxime Chloride / administration & dosage*
  • Organothiophosphorus Compounds / poisoning*
  • Poisoning / blood
  • Poisoning / drug therapy*
  • Poisoning / enzymology
  • Severity of Illness Index
  • Suicide, Attempted
  • Time Factors
  • Treatment Outcome
  • Up-Regulation

Substances

  • Antidotes
  • Biomarkers
  • Cholinesterase Inhibitors
  • Cholinesterase Reactivators
  • GPI-Linked Proteins
  • Insecticides
  • Organothiophosphorus Compounds
  • Obidoxime Chloride
  • methamidophos
  • ACHE protein, human
  • Acetylcholinesterase