The ability of a novel bispyridinium oxime K870 and currently available oximes (pralidoxime, HI-6) to reactivate sarin-inhibited acetylcholinesterase and to reduce acute toxicity of sarin was evaluated. In vivo determined percentage of reactivation of sarin-inhibited rat blood, diaphragm and brain acetylcholinesterase showed that the potency of newly developed oxime K870 to reactivate sarin-inhibited acetylcholinesterase roughly corresponds to the reactivating efficacy of pralidoxime with the exception of diaphragm where the oxime K870 was more effective than pralidoxime. However, the oxime HI-6 was found to be the most efficient reactivator of sarin-inhibited acetylcholinesterase. While the oxime HI-6 was able to reduce the acute toxicity of sarin more than five times, the novel oxime K870 and pralidoxime decreased the acute toxicity of sarin less than three times. Based on the results, we can conclude that the reactivating and therapeutic efficacy of newly developed oxime K870 is significantly lower compared to the oxime HI-6 and, therefore, it is not suitable for the replacement of the oxime HI-6 for the antidotal treatment of acute sarin poisoning.

Keywords: sarin; acetylcholinesterase; K870; pralidoxime; HI-6