[Effect of acetylcholinesterase reactivator dosage on its effectiveness in the treatment of tabun poisoning in mice].

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 experiments on male mice. A comparison of the values of the medium lethal dose (LD50) of tabun in the intoxication influenced by an antidote therapy consisting of atropin and some of the oximes tested revealed that in all three oximes under study their dose markedly influenced their effect. The highest efficacy was 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 tested that 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% of LD50) the differences between the therapeutic efficacy of the individual oximes are not statistically significant. Oxime HI-6 is significantly more effective than obidoxime (in a dose corresponding to 20% of LD50), but it is less effective than trimedoxime (in a dose corresponding to 5% LD50). The achieved results have shown that oxime HI-6, so effective against soman, another nerve agent, is not the most advantageous reactivator of acetylcholinesterase for the therapy of acute tabun poisonings, though its efficacy is partly eliminated by its possible higher dosing in human medicine due to its lower toxicity for mammals. The most suitable reactivator of acetylcholinesterase for the elimination of acute lethal toxic effects of tabun seems to be trimedoxime. Obidoxime, which is the most widely used reactivator of acetylcholinesterase in the therapy of poisonings by nerve agents at present, is, like in the case of soman poisonings, a relatively least suitable oxime ensuring the survival in lethal tabun poisonings.