(-)Huperzine A, Replacement For Pyridostigmine Bromide As Nerve Agent Pretreatment, Measured In Guinea Pig Plasma By A New Ultrahigh-Pressure Liquid Chromatography (Uhplc)-Ms Method

Huperzines are a class a of compounds extractable alkaloids from the club moss Huperzia serretia. Moss extract, as a tea, has been used in China to improve cognitive abilities. (‐) Huperzine A (HUP) is a potent reversible acetylcholinesterase inhibitor that can cross the blood‐brain barrier. It is under investigation as an Alzheimer's treatment. These properties may also be useful for a protection against organophosphate (OP) nerve agent poisoning of peripheral and CNS acetylcholinesterase. The guinea pig is the rodent model of choice for OP studies. It has low circulating levels of OP hydrolyzing carboxylesterase, like humans, but unlike rats or mice with high levels that can complicate protection studies. For HUP guinea pig studies we developed an ultrahigh‐pressure liquid chromatography (UHPLC)‐MS method with solid phase extraction (SPE) clean up. HUP recovery from SPE was > 90% for range 0.5 to 20 ng/mL. The UHPLC‐MS was sensitive with an LOD limit of 1 pg. The limits LOQ were 0.32 to 1000 ng/mL (highest tested) with the LLOQ 5 x S/N. Here we demonstrate assay utility in pilot ADME studies in guinea pig plasma from single I.M. doses of 3, 9, and 18 mg/kg. This work was supported by the Defense Threat Reduction Agency.