title: Investigation of the selective androgen receptor modulators S1, S4 and S22 and their metabolites in equine plasma using high-resolution mass spectrometry.
abstract: BACKGROUND
  Selective androgen receptor modulators (SARMs) are prohibited in sports due to their performance enhancing ability. It is important to investigate the metabolism to determine appropriate targets for doping control. This is the first study where the equine metabolites of SARMs S1, S4 (Andarine) and S22 (Ostarine) have been studied in plasma.
  
  
  METHODS
  Each SARM was administered to three horses as an intravenous bolus dose and plasma samples were collected. The samples were pretreated with protein precipitation using cold acetonitrile before separation by liquid chromatography. The mass spectrometric analysis was performed using negative electrospray, quadrupole time-of-flight mass spectrometry operated in MS(E) mode and triple-quadrupole mass spectrometry operated in selected reaction monitoring mode. For the quantification of SARM S1, a deuterated analogue was used as internal standard.
  
  
  RESULTS
  The numbers of observed metabolites were eight, nine and four for the SARMs S1, S4 and S22, respectively. The major metabolite was formed by the same metabolic reactions for all three SARMs, namely amide hydrolysis, hydroxylation and sulfonation. The values of the determined maximum plasma concentrations were in the range of 97-170 ng/mL for SARM S1, 95-115 ng/mL for SARM S4 and 92-147 ng/mL for SARM S22 and the compounds could be detected for 96 h, 12 h and 18 h, respectively.
  
  
  CONCLUSIONS
  The maximum plasma concentration of SARMs S1, S4 and S22 was measured in the first sample (5 min) after administration and they were eliminated fast from plasma. The proposed targets to be used in equine doping control are the parent compounds for all three SARMs, but with the metabolite yielding the highest response as a complementary target. Copyright © 2016 John Wiley & Sons, Ltd.
authors.affiliation: Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123, Uppsala, Sweden.
authors.forename: Annelie
authors.initials: A
authors.lastname: Hansson
authors.affiliation: K. L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA, USA.|Department of Veterinary Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Heather
authors.initials: H
authors.lastname: Knych
authors.affiliation: K. L. Maddy Equine Analytical Chemistry Laboratory, School of Veterinary Medicine, University of California, Davis, CA, USA.
authors.forename: Scott
authors.initials: S
authors.lastname: Stanley
authors.affiliation: Institute of Biochemistry and Center for Preventive Doping Research, German Sport University, Cologne, Germany.
authors.forename: Mario
authors.initials: M
authors.lastname: Thevis
authors.affiliation: Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123, Uppsala, Sweden.|National Veterinary Institute (SVA), Department of Chemistry, Environment and Feed Hygiene, SE-75651, Uppsala, Sweden.
authors.forename: Ulf
authors.initials: U
authors.lastname: Bondesson
authors.affiliation: Division of Analytical Pharmaceutical Chemistry, Department of Medicinal Chemistry, Uppsala University, Box 574, SE-75123, Uppsala, Sweden.|National Veterinary Institute (SVA), Department of Chemistry, Environment and Feed Hygiene, SE-75651, Uppsala, Sweden.
authors.forename: Mikael
authors.initials: M
authors.lastname: Hedeland
mesh_terms: D000081:Acetamides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D000577:Amides / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D000627:Aminophenols / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D045930:Anabolic Agents / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D000728:Androgens / Q000032:analysis* / Q000737:chemistry / Q000378:metabolism; D000813:Anilides; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D005260:Female; D006736:Horses; D057230:Limit of Detection; D053719:Tandem Mass Spectrometry
chemical_list: D000081:Acetamides; D000577:Amides; D000627:Aminophenols; D045930:Anabolic Agents; D000728:Androgens; D000813:Anilides; C492992:andarine; C547106:ostarine