Effect of a Dose of Acetylcholinesterase Reactivators on Their Efficiency in the Therapyof Tabun Poisoning in Mice

Overview

The therapeutic efficacy of selected reactivators of acetylcholinesterase (obidoxime, oxime HI-6,trimedoxime) against acute tabun poisoning in dependence on their dose was examined in experimentson male mice. A comparison of the values of the medium lethal dose (LD50) of tabun in theintoxication influenced by an antidote therapy consisting of atropin and some of the oximes testedrevealed that in all three oximes under study their dose markedly influenced their effect.The highestefficacywas always achieved when oximes were administered in the maximal therapeutic dose (20 %of LD50). It follows from the comparison of the efficacy of equieffective doses of the oximes testedthat in all doses the acute lethal effects of tabun are most effectively eliminated by trimedoxime,and on the other hand, obidoxime seems to be least effective, though in the smallest dose tested (2 %ofLD50) the differences between the therapeutic efficacy of the individual oximes are not statisticallysignificant. Oxime HI-6 is significantly more effective than obidoxime (in a dose corresponding to20 % of LD50), but it is less effective than trimedoxime (in a dose corresponding to 5 % LD50). Theachieved results have shown that oxime HI-6, so effective against soman, another nerve agent, isnot the most advantageous reactivator of acetylcholinesterase for the therapy of acute tabunpoisonings, though its efficacy is partly eliminated by its possible higher dosing in human medicinedue to its lower toxicity for mammals. The most suitable reactivator of acetylcholinesterase for theelimination of acute lethal toxic effects of tabun seems to be trimedoxime. Obidoxime, which is themost widely used reactivator of acetylcholinesterase in the therapy of poisonings by nerve agentsat present, is, like in the case of soman poisonings, a relatively least suitable oxime ensuring thesurvival in lethal tabun poisonings.

Key words:
tabun – mouse – oxime HI-6 – obidoxime – trimedoxime – atropine – dose dependence