title: Signal Enhancement in the HPLC-ESI-MS/MS analysis of spironolactone and its metabolites using HFIP and NH4F as eluent additives.
abstract: This paper describes an LC-MS/MS method to determine the concentration of spironolactone and its metabolites 7-alpha-methylthiospironolactone and canrenone in blood plasma samples. The resulting assay is simple (using protein precipitation for sample preparation) and sensitive (the lower limit of quantification is close to 0.5 ng/ml) while requiring only 50 μl of plasma, making it especially suitable for analyzing samples obtained from pediatric and neonatal patients where sample sizes are limited. The sensitivity is achieved by using ammonium fluoride as an eluent additive, which in our case amplifies the signal from our analytes in the plasma solution on average about 70 times. The method is fully validated according to the European Medicines Agency's guideline and used for the measurement of pediatric patients' samples in clinical trials for evaluating oral spironolactone's and its metabolites' pharmacokinetics in children up to 2 years of age.
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila Street, Tartu, 50411, Estonia.
authors.forename: Kalev
authors.initials: K
authors.lastname: Takkis
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila Street, Tartu, 50411, Estonia.
authors.forename: Rudolf
authors.initials: R
authors.lastname: Aro
authors.affiliation: Children's Clinic, Tartu University Hospital, N. Lunini 6, Tartu, 51014, Estonia.|Institute of Biomedicine and Translational Medicine, Department of Pharmacology, University of Tartu, Ravila 19, Tartu, 50411, Estonia.
authors.forename: Lenne-Triin
authors.initials: LT
authors.lastname: Kõrgvee
authors.affiliation: Children's Clinic, Tartu University Hospital, N. Lunini 6, Tartu, 51014, Estonia.
authors.forename: Heili
authors.initials: H
authors.lastname: Varendi
authors.affiliation: Pharmacy Department, Tartu University Hospital, L. Puusepa 8, Tartu, 51014, Estonia.|Institute of Biomedicine and Translational Medicine, Department of Microbiology, University of Tartu, Ravila 19, Tartu, 50411, Estonia.
authors.forename: Jana
authors.initials: J
authors.lastname: Lass
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila Street, Tartu, 50411, Estonia.
authors.forename: Koit
authors.initials: K
authors.lastname: Herodes
authors.affiliation: Institute of Chemistry, University of Tartu, 14a Ravila Street, Tartu, 50411, Estonia. karin.kipper@gmail.com.|Paediatric Infectious Diseases Research Group, Institute for Infection and Immunity, St. George's, University of London, Cranmer Terrace, London, SW17 0RE, UK. karin.kipper@gmail.com.
authors.forename: Karin
authors.identifier: http://orcid.org/0000-0002-7295-8993
authors.initials: K
authors.lastname: Kipper
mesh_terms: D002192:Canrenone / Q000097:blood* / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods*; D006801:Humans; D057230:Limit of Detection; D000451:Mineralocorticoid Receptor Antagonists / Q000097:blood* / Q000378:metabolism; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D013148:Spironolactone / Q000031:analogs & derivatives* / Q000097:blood* / Q000378:metabolism; D053719:Tandem Mass Spectrometry / Q000379:methods*
chemical_list: D000451:Mineralocorticoid Receptor Antagonists; D013148:Spironolactone; C033554:7 alpha-thiospironolactone; D002192:Canrenone
keywords: Ammonium fluoride; Hexafluoroisopropanol; Ionization efficiency; Liquid chromatography-mass spectrometry; Signal enhancement; Spironolactone