Rosenberg_2018_Toxicol.Lett_293_229

Fatalities from organophosphate (OP) insecticide result from both occupational and deliberate exposure; significantly impacting human health. Like nerve agents, insecticides are neurotoxins which target and inhibit acetylcholinesterases (AChE) in central and peripheral synapses in the cholinergic nervous system. Post-exposure therapeutic countermeasures generally include administration of atropine with a pyridinium aldoximes e.g. pralidoxime, to reactivate the OP-inhibited AChE. However, commonly used oximes inefficiently cross the blood brain barrier and are rapidly cleared and their benefit is debated. Recent findings have demonstrated the ability of a novel zwitterionic, centrally acting, brain penetrating oxime (RS194B) to reverse severe symptoms and rapidly reactivate sarin-inhibited AChE in macaques but has not been tested following OP pesticide poisoning. The severe symptoms following a lethal dose of inhaled paraoxon (100ug/kg), which mimicked those in insecticide poisoned individuals, were rapidly reversed in macaques by post-exposure IM administration of 80mg/kg of RS194B. This occurred with a concomitant reactivation of AChE to 40-100% in <1hr and BChE (40% in 8hr). These findings will be used to develop a macaque model with RS194B as a post-exposure treatment for insecticide poisoning and generate efficacy data for approval under the FDA Animal rule.