title: Simulation of cholinesterase status at different scenarios of nerve agent exposure.
abstract: The ongoing threat of homicidal use of organophosphorus-type chemical warfare agents ("nerve agents") during military conflicts and by terrorists underlines the necessity for effective medical countermeasures. Standard treatment with atropine and the established acetylcholinesterase (AChE) reactivators, obidoxime and pralidoxime, is considered to be ineffective with certain nerve agents due to low oxime effectiveness. From obvious ethical reasons only animal experiments can be used to evaluate new oximes as nerve agent antidotes. However, the extrapolation of data from animal to humans is hampered by marked species differences. Since reactivation of OP-inhibited AChE is considered to be the main mechanism of action of oximes, human erythrocyte AChE can be exploited to test the efficacy of new oximes. Recently, a dynamic computer model was developed which allows the calculation of AChE activities at different scenarios by combining enzyme kinetics (inhibition, reactivation, aging) with OP toxicokinetics and oxime pharmacokinetics. Now, this computer model was further extended by including the pharmaco- and enzyme kinetics of carbamate pretreatment. Simulations were performed for intravenous and percutaneous nerve agent exposure and intramuscular oxime treatment in the presence and absence of pyridostigmine pretreatment using published data. The model presented may serve as a tool for evaluating the impact of carbamate pretreatment on oxime-induced reactivation of inhibited AChE, for defining effective oxime concentrations and for optimizing oxime treatment. In addition, this model may be useful for the development of meaningful therapeutic strategies in animal experiments.
authors.affiliation: Bundeswehr Institute of Pharmacology and Toxicology, Neuherbergstrasse 11, 80937 Munich, Germany. FranzWorek@Bundeswehr.org
authors.forename: Franz
authors.initials: F
authors.lastname: Worek
authors.forename: Peter
authors.initials: P
authors.lastname: Eyer
authors.forename: Ladislaus
authors.initials: L
authors.lastname: Szinicz
authors.forename: Horst
authors.initials: H
authors.lastname: Thiermann
mesh_terms: D000818:Animals; D002619:Chemical Warfare Agents / Q000493:pharmacokinetics / Q000506:poisoning*; D002801:Cholinesterase Reactivators / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D002802:Cholinesterases / Q000378:metabolism*; D003198:Computer Simulation; D004305:Dose-Response Relationship, Drug; D006801:Humans; D008954:Models, Biological; D020258:Neurotoxicity Syndromes / Q000201:enzymology / Q000517:prevention & control; D009946:Organothiophosphorus Compounds / Q000493:pharmacokinetics / Q000506:poisoning*; D010091:Oximes / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D011292:Premedication; D013997:Time Factors
chemical_list: D002619:Chemical Warfare Agents; D002801:Cholinesterase Reactivators; D002802:Cholinesterases; D009946:Organothiophosphorus Compounds; D010091:Oximes; C009680:VX-agent