A simple, rapid and sensitive method for simultaneous determination of rivastigmine and its major metabolite NAP 226‐90 in rat brain and plasma by reversed‐phase liquid chromatography coupled to electrospray ionization mass spectrometry

Publisher Website
Google Scholar
Abstract
A simple and sensitive reversed-phase liquid chromatography coupled with electrospray–mass spectrometry was developed and validated for the simultaneous determination of rivastigmine, a cholinesterase inhibitor, and its major metabolite NAP 226-90 in rat plasma and brain homogenates. Rivastigmine and NAP 226-90 were extracted from plasma and brain by ethyl acetate and, after drying under nitrogen, re-dissolved in acetonitrile and separated isocratic by HPLC on a C18 column and quantified by single ion monitoring mass spectrometer. The mean (±SD) extraction efficiency for rivastigmine in plasma and brain was 93 ± 2 and 95 ± 2% (n = 5) of NAP 226-90 in a drug range of 10–100 pmol/mL or pmol/g. The method proved to be linear within the tested range (regression coefficient, r = 0.9999, n = 5). Intra- and inter-day precision coefficients of variation and accuracy bias were acceptable (within 15%, n = 5) over the entire range for both compounds using plasma or brain samples. The limits of quantification were 0.5 pmol/mL plasma and 2.5 pmol/g brain for rivastigmine and 1 pmol/mL plasma and 5 pmol/g brain for NAP 226-90, respectively. The analytical technique was used to determine the concentrations of rivastigmine and its metabolite NAP 226-90 in rat plasma and brain after oral drug administration. The concentrations of the parent drug and its major metabolite were compared to a pharmacodynamic parameter, the ex vivo inhibition of acetylcholinesterase. Copyright © 2003 John Wiley & Sons, Ltd.