A Comparison of the Neuroprotective and Reactivating Efficacy of a Novel Bispyridinium Oxime K870 with Commonly Used Pralidoxime and the Oxime HI-6 in Tabun-Poisoned Rat

Aim: The comparison of neuroprotective and central reactivating effects of the oxime K870 in combination with atropine with the efficacy of standard antidotal treatment in tabun-poisoned rats. Methods: The neuroprotective effects of antidotal treatment were determined in rats poisoned with tabun at a sublethal dose using a functional observational battery 2 h and 24 h after tabun administration, the tabun-induced brain damage was investigated by the histopathological evaluation and central reactivating effects of oximes was evaluated by the determination of acetylcholinesterase activity in the brain using a standard spectrophotometric method. Results: The central reactivating efficacy of a newly developed oxime K870 roughly corresponds to the central reactivating efficacy of pralidoxime while the ability of the oxime HI-6 to reactivate tabun-inhibited acetylcholinesterase in the brain was negligible. The ability of the oxime K870 to decrease tabun-induced acute neurotoxicity was slightly higher than that of pralidoxime and similar to the oxime HI-6. These results roughly correspond to the histopathological evaluation of tabun-induced brain damage. Conclusion: The newly synthesized oxime K870 is not a suitable replacement for commonly used oximes in the antidotal treatment of acute tabun poisonings because its neuroprotective efficacy is only slightly higher or similar compared to studied currently used oximes.