title: Repetitive obidoxime treatment induced increase of red blood cell acetylcholinesterase activity even in a late phase of a severe methamidophos poisoning: A case report.
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.
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937 Munich, Germany; Walther-Straub-Institute of Pharmacology and Toxicology, Ludwig-Maximilians-University Munich, 80336 Munich, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Steinritz
authors.affiliation: Department of Toxicology, University Hospital Klinikum Rechts der Isar, Technical University Munich, 81675 Munich, Germany.
authors.forename: Florian
authors.initials: F
authors.lastname: Eyer
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937 Munich, Germany.
authors.forename: Franz
authors.initials: F
authors.lastname: Worek
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937 Munich, Germany.
authors.forename: Horst
authors.initials: H
authors.lastname: Thiermann
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstraße 11, 80937 Munich, Germany. Electronic address: haraldjohn@bundeswehr.org.
authors.forename: Harald
authors.initials: H
authors.lastname: John
mesh_terms: D000110:Acetylcholinesterase / Q000097:blood*; D000368:Aged; D000931:Antidotes / Q000008:administration & dosage*; D015415:Biomarkers / Q000097:blood; D002800:Cholinesterase Inhibitors / Q000506:poisoning*; D002801:Cholinesterase Reactivators / Q000008:administration & dosage*; D004334:Drug Administration Schedule; D004912:Erythrocytes / Q000187:drug effects* / Q000201:enzymology; D058851:GPI-Linked Proteins / Q000097:blood; D006801:Humans; D007306:Insecticides / Q000506:poisoning*; D008297:Male; D009768:Obidoxime Chloride / Q000008:administration & dosage*; D009946:Organothiophosphorus Compounds / Q000506:poisoning*; D011041:Poisoning / Q000097:blood / Q000188:drug therapy* / Q000201:enzymology; D012720:Severity of Illness Index; D013406:Suicide, Attempted; D013997:Time Factors; D016896:Treatment Outcome; D015854:Up-Regulation
chemical_list: D000931:Antidotes; D015415:Biomarkers; D002800:Cholinesterase Inhibitors; D002801:Cholinesterase Reactivators; D058851:GPI-Linked Proteins; D007306:Insecticides; D009946:Organothiophosphorus Compounds; D009768:Obidoxime Chloride; C014655:methamidophos; C548244:ACHE protein, human; D000110:Acetylcholinesterase
keywords: Intoxication; Methamidophos; Organophosphorus compounds; Red blood cell acetylcholinesterase; obidoxime