title: A liquid chromatography-mass spectrometry assay for quantification of Exendin[9-39] in human plasma.
abstract: Exendin[9-39] is a glucagon-like peptide-1 receptor (GLP-R) antagonist and a potential therapeutic drug for treatment of congenital hyperinsulism by lowering insulin concentration in plasma. A specific and sensitive LC-MS/MS method was validated for quantification of Exendin[9-39] in human plasma. Exendin[9-39] and the stable isopically labeled internal standard eluted at 9.2 min and were analyzed by single reaction monitoring (SRM) of the transitions m/z 842.9→991.8 and 848.2→998.8, respectively. The calibration curve was linear in the range 15-1260 ng/mL with a limit of detection of 1.3 ng/mL. The CVs of the standards were 2.7-13.1% within-run and 3.1-13.2% between-run. The matrix effect was >100% and the SPE recovery was 98.4±12.9%. In absence of protease inhibitors, short-term stability at room temperature was only one hour. Accordingly, samples were kept on ice and sample processing was kept below 1h. Human plasma samples from a clinical pilot study in which Exendin[9-39] was administered intravenously were analyzed and concentrations up to 600 ng/mL were reported Plasma samples from the study were stored at -80 °C with internal standard and successfully reanalyzed after 12 months.
authors.affiliation: Protein and Proteomics Core Facility, The Children's Hospital of Philadelphia Research Institute, 3615 Civic Center Boulevard, Abramson Research Center, 816a, Philadelphia, PA 19104, United States.
authors.forename: Maria
authors.initials: M
authors.lastname: Lasaosa
authors.affiliation: Division of Endocrinology/Diabetes, The Children's Hospital of Philadelphia, 3615 Civic Center Boulevard, Abramson Research Center, 802, Philadelphia, PA 19104, United States.
authors.forename: Puja
authors.initials: P
authors.lastname: Patel
authors.affiliation: Division of Endocrinology/Diabetes, The Children's Hospital of Philadelphia, 3615 Civic Center Boulevard, Abramson Research Center, 802, Philadelphia, PA 19104, United States.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Givler
authors.affiliation: Division of Endocrinology/Diabetes, The Children's Hospital of Philadelphia, 3615 Civic Center Boulevard, Abramson Research Center, 802, Philadelphia, PA 19104, United States; Department of Pediatrics, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, United States.
authors.forename: Diva D
authors.initials: DD
authors.lastname: De León
authors.affiliation: Protein and Proteomics Core Facility, The Children's Hospital of Philadelphia Research Institute, 3615 Civic Center Boulevard, Abramson Research Center, 816a, Philadelphia, PA 19104, United States. Electronic address: seeholzer@email.chop.edu.
authors.forename: Steven H
authors.initials: SH
authors.lastname: Seeholzer
mesh_terms: D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D007004:Hypoglycemic Agents / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D053719:Tandem Mass Spectrometry
chemical_list: D007004:Hypoglycemic Agents; D010446:Peptide Fragments; C083773:exendin (9-39)
keywords: DPP-4; Dipeptidyl peptidase-4; Exendin[9-39]; GLP-1; GLP-R; Glucagon-like peptide-1 receptor; HI; Hyperinsulinism; LC–MS/MS; LLOQ; Lower limit of quantification; Peptide quantification; SD; SPE; SRM; Selected reaction monitoring; Solid-phase extraction; Standard Deviation; Triple quadrupole mass spectrometry; ULOQ; Upper limit of quantification