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.
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 C(18) 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.
Enz
Albert
A
Novartis Institutes for BioMedical Research Basel, Novartis Pharma AG, CH-4002 Basel/Switzerland. albert.enz@pharma.novartis.com
Chappuis
Alain
A
Dattler
Andre
A
D000818:Animals; D001596:Benzylamines / Q000097:blood / Q000378:metabolism*; D002800:Cholinesterase Inhibitors / Q000097:blood / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods*; D010627:Phenethylamines; D010636:Phenols / Q000097:blood / Q000378:metabolism*; D048448:Phenylcarbamates / Q000097:blood / Q000378:metabolism*; D051381:Rats; D015203:Reproducibility of Results; D000068836:Rivastigmine; D012680:Sensitivity and Specificity; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods*
C494046:3-(1-dimethylaminoethyl)phenol; D001596:Benzylamines; D002800:Cholinesterase Inhibitors; D010627:Phenethylamines; D010636:Phenols; D048448:Phenylcarbamates; D000068836:Rivastigmine