title: Three complementary liquid chromatographic methods for determination of the peptoid cholecystokinin-B antagonist, CI-988, in rat plasma.
abstract: Three different liquid chromatographic methods (two quantitative methods which employ fluorescence detection and one qualitative method which employs selected ion-monitoring detection) were developed and validated to provide complementary specificity for determination of CI-988, a cholecystokinin-B antagonist, in rat plasma. The first quantitative method involves isocratic separation of "non-ionized" CI-988 and internal standard on a C-18 column, whereas the alternative quantitative method involves isocratic separation of the "anionic" analytes. These two quantitative HPLC methods rely on the intrinsic fluorescence of CI-988 and internal standard for detection, and both methods are equally sensitive (linear range of 2.0-1000 ng ml-1), accurate (+/- 15% relative error), and precise (< or = 15% relative standard deviation). Plasma CI-988 concentrations for samples (N = 69) assayed with the "non-ionized" separation are linearly correlated with concentrations for the same samples assayed with the "anionic" separation (y = 1.08 chi - 0.57, R = 0.999). In addition, a third qualitative method, HPLC-thermospray mass spectrometry, was developed to provide complementary evaluation of assay specificity through the use of selected CI-988 fragment ion monitoring. When investigating an anomalous chromatographic result that calls into question the specificity of a method, the availability and use of alternative validated chromatographic separations and orthogonal detection schemes are beneficial.
authors.affiliation: Pharmacokinetics/Drug Metabolism Department, Parke-Davis Pharmaceutical Research, Division of Warner-Lambert Company, Ann Arbor, MI 48105, USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Hinton
authors.forename: J C
authors.initials: JC
authors.lastname: Pablo
authors.forename: S M
authors.initials: SM
authors.lastname: Bjorge
authors.forename: K
authors.initials: K
authors.lastname: Hoffman
authors.forename: K
authors.initials: K
authors.lastname: Jennings
authors.forename: D S
authors.initials: DS
authors.lastname: Wright
mesh_terms: D000818:Animals; D000838:Anions; D002766:Cholecystokinin / Q000037:antagonists & inhibitors*; D002851:Chromatography, High Pressure Liquid; D006727:Hormone Antagonists / Q000097:blood*; D007211:Indoles / Q000097:blood*; D013058:Mass Spectrometry; D008536:Meglumine / Q000031:analogs & derivatives* / Q000097:blood; D034444:Peptoids; D051381:Rats; D012015:Reference Standards; D015203:Reproducibility of Results; D013050:Spectrometry, Fluorescence
chemical_list: D000838:Anions; D006727:Hormone Antagonists; D007211:Indoles; D034444:Peptoids; C065599:PD 134308; D008536:Meglumine; D002766:Cholecystokinin