Evaluation of the neuroprotective efficacy of individual oxime (HI-6) and oxime mixtures (HI-6 + trimedoxime, HI-6 + K203) in tabun-poisoned rats

The ability of the oxime HI-6 to reduce tabun-induced acute neurotoxic signs and symptoms was compared with the neuroprotective efficacy of two combinations of oximes (HI-6 + trimedoxime, HI-6 + K203) using a functional observational battery. Tabun-induced neurotoxicity and the neuroprotective effects of HI-6 alone, and HI-6 combined with trimedoxime or K203, in rats poisoned with tabun at a sublethal dose (200 μg/kg i.m.; 80% of LD50 value), were monitored by the functional observational battery at 24 hours following tabun challenge. The results indicate that both oxime mixtures tested, combined with atropine are able to allow tabun-poisoned rats to survive for 24 hours following tabun challenge, while one non-treated tabun poisoned rat and one tabun-poisoned rat treated with the oxime HI-6 alone combined with atropine, died within 24 hours following tabun challenge. The oxime HI-6 alone, as well as both oxime mixtures combined with atropine, were able to decrease tabun-induced neurotoxicity in the case of sublethal poisonings, but they did not eliminate all tabun-induced acute neurotoxic signs and symptoms. Their ability to reduce tabun-induced acute neurotoxcicity was almost the same, regardless of type of antidotal treatment. Thus, the tested combinations of oximes were not able to increase the neuroprotective effectiveness of the antidotal treatment of acute tabun poisonings compared to the individual oxime.