title: Determination of felodipine, its enantiomers, and a pyridine metabolite in human plasma by capillary gas chromatography with mass spectrometric detection.
abstract: Sensitive methods based on capillary gas chromatography (GC) with mass spectrometric (MS) detection in a selected-ion monitoring mode (SIM) for the determination of racemic felodipine, its enantiomers, and a pyridine metabolite in human plasma are described. Following liquid-liquid extraction from plasma, enantiomers of felodipine were separated on a chiral HPLC column (Chiralcel OJ) and fractions containing each isomer were collected on a continuous basis using a fraction collector. These fractions were later analyzed by GC-MS-SIM. A similar method based on GC-MS-SIM detection was developed for the determination of racemic felodipine and its pyridine metabolite with a minor modification of sample preparation. The limits of quantitation in plasma were 0.1 ng/ml for both the R(+)- and S(-)-enantiomers of felodipine and 0.5 ng/ml for both racemic felodipine and its pyridine metabolite. The stereoselective assay was used to support a clinical study with racemic felodipine, and was capable of analyzing more than 30 plasma samples per day.
authors.affiliation: Department of Drug Metabolism, Merck Research Laboratories, West Point, PA 19486, USA.
authors.forename: J D
authors.initials: JD
authors.lastname: Dru
authors.forename: J Y
authors.initials: JY
authors.lastname: Hsieh
authors.forename: B K
authors.initials: BK
authors.lastname: Matuszewski
authors.forename: M R
authors.initials: MR
authors.lastname: Dobrinska
mesh_terms: D015736:Felodipine / Q000097:blood* / Q000737:chemistry; D008401:Gas Chromatography-Mass Spectrometry / Q000379:methods*; D006801:Humans; D011725:Pyridines / Q000097:blood*; D015203:Reproducibility of Results; D013237:Stereoisomerism
chemical_list: D011725:Pyridines; C023666:pyridine; D015736:Felodipine