Determination of neostigmine in human plasma and cerebrospinal fluid by high-performance liquid chromatography with...

A high-performance liquid chromatographic assay coupled with ultraviolet detection has been developed for the determination of neostigmine in human plasma and cerebrospinal fluid. A novel solid-phase extraction procedure was first used for this analyte and allowed good recovery (89+/-4.5%) together with ease and speed of execution. The method was sensitive, reproducible (C.V.<4.5%) and accurate (100+/-6.6%) over the range 2.6-167.0 ng/ml neostigmine concentrations in plasma or cerebrospinal fluid, and was applied successfully to study the pharmacokinetics of neostigmine in patients suffering from chronic postoperative abdominal pain.