title: Simultaneous quantification of phencynonate and its active metabolite N-demethyl phencynonate in human plasma using liquid chromatography and isotope-dilution mass spectrometry.
abstract: A sensitive and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed to simultaneously quantify phencynonate (PCN) and its major metabolite N-demethyl phencynonate (DM-PCN) in human plasma. Following one-step liquid-liquid extraction, the analytes were separated on a reversed-phase C18 column. Methanol and 0.02% formic acid in 10 mM ammonium acetate (62:38, v/v) was used as isocratic mobile phase at a flow-rate of 0.3 mL/min. An API 5000 tandem mass spectrometer equipped with a Turbo IonSpray ionization source was used as the detector and was operated in the positive ion mode. Multiple reaction monitoring using the transition of m/z 358.4 → m/z 156.2, m/z 344.4 → m/z 142.2, and m/z 361.3 → m/z 159.2 was performed to quantify PCN, DM-PCN, and the internal standard (D3 -PCN), respectively. This approach showed a lower limit of quantification of 10 pg/mL and 25 pg/mL for PCN and DM-PCN in plasma, respectively. This sensitivity was at least 50-fold superior to previously reported ones and thus enabled the approach well applicable to low-dose pharmacokinetic studies. The intra- and inter-day precisions were less than 14.2 % at each QC level for both PCN and DM-PCN. The inter-day relative errors ranged from -1.9% to -4.9% for PCN, and from 0.6% to 6.4% for DM-PCN. As a proof of principle, the validated method was successfully applied to simultaneous quantification of circulating PCN and DM-PCN in healthy subjects after a single oral administration of 2 mg phencynonate hydrochloride pellet.
authors.affiliation: Bao Di Clinical College of Tianjin Medical University, Tianjin, 301800, China.
authors.forename: Zhengang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Bao Di Clinical College of Tianjin Medical University, Tianjin, 301800, China.
authors.forename: Hui
authors.initials: H
authors.lastname: Xie
authors.affiliation: Bao Di Clinical College of Tianjin Medical University, Tianjin, 301800, China.
authors.forename: Jinbo
authors.initials: J
authors.lastname: Liu
authors.affiliation: Bao Di Clinical College of Tianjin Medical University, Tianjin, 301800, China.
authors.forename: Guangshun
authors.initials: G
authors.lastname: Wang
mesh_terms: D000284:Administration, Oral; D001372:Aza Compounds / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism*; D018680:Cholinergic Antagonists / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism*; D002853:Chromatography, Liquid / Q000379:methods; D006016:Glycolates / Q000008:administration & dosage / Q000097:blood* / Q000378:metabolism*; D006801:Humans; D007201:Indicator Dilution Techniques; D057230:Limit of Detection; D059625:Liquid-Liquid Extraction / Q000379:methods; D008297:Male; D008745:Methylation; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: C504860:3-methyl-3-azabicyclo(3,3,1)nonanyl-9-alpha-yl-alpha-cyclopentyl-alpha-phenyl-alpha-glycolate; D001372:Aza Compounds; D018680:Cholinergic Antagonists; D006016:Glycolates
keywords: N-demethyl phencynonote; clinic pharmacokinetics; isotope-dilution LC-MS; phencynonate