Protection against nerve agent poisoning by a noncompetitive nicotinic antagonist

Turner, S.R., Chad, J.E., Price, M., Timperley, C.M., Bird, M., Green, A.C. and Tattersall, J.E.H. (2011) Protection against nerve agent poisoning by a noncompetitive nicotinic antagonist. [in special issue: Selected papers from the 13th Medical Chemical Defence Conference 2011: New Developments in the treatment of intoxications by chemical warfare agents with focus on neurotoxic agents] Toxicology Letters, 206 (1), 105-111. (doi:10.1016/j.toxlet.2011.05.1035). (PMID:21641979)

Abstract

The acute toxicity of organophosphorus (OP) nerve agents arises from accumulation of acetylcholine (ACh) and overstimulation of ACh receptors. The mainstay of current pharmacotherapy is the competitive muscarinic antagonist, atropine. Nicotinic antagonists have not been used due to the difficulties of administering a dose of a competitive neuromuscular blocker sufficient to antagonise the effects of excessive ACh, but not so much that it paralyses the muscles. An alternative approach would be to use a noncompetitive antagonist whose effects would not be overcome by increasing ACh concentrations. This study demonstrates that the compound 1,1'-(propane-1,3-diyl)bis(4-tert-butylpyridinium), which blocks open nicotinic ion channels noncompetitively, is able to reverse the neuromuscular paralysis after nerve agent poisoning in vitro and to protect guinea pigs against poisoning by nerve agents when used as part of a therapeutic drug combination including a muscarinic antagonist. In contrast to the oxime HI-6, this compound was equally effective in protecting against poisoning by sarin or tabun. Further studies should identify more effective compounds with this action and optimise doses for protection against nerve agent poisoning in vivo.

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Contributors

Author: J.E. Chad

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