title: Testosterone administration to mares: criteria for detection of testosterone abuse by analysis of metabolites in plasma and urine.
abstract: A pharmacological dose of a long-acting testosterone ester, testosterone hexahydrobenzoate, was administered intramuscularly to two mares. The time course for some characteristic metabolites in blood and urine was then studied using an analytical method based on gas chromatography-mass spectrometry associated with stable isotope dilution. Among the plasma analytes, testosterone glucuronide was found to be the most adequate indicator for the monitoring of exogenous testosterone up to 2 weeks postadministration if a threshold value of 200 ng/L was applied. In urine, the simultaneous measurement of the concentrations of testosterone sulfate (TS) and epitestosterone sulfate (ES) allowed the calculation of the concentration ratio, TS/ES, which was independent of urine flow and which offered the possibility of detecting testosterone misuse 20 to 30 days after dosing if a tentative threshold value of 8 was adopted. In addition to this ratio, particularly when the TS/ES ratio was close to the cutoff point, it seemed advisable to take into account the concentrations of 5 alpha-androstane-3 beta, 17 alpha-diol (glucuronide) and its 17 beta-isomer (sulfate), which should not exceed 50 micrograms/L.
authors.affiliation: Laboratoire de la Fédération Nationale des Sociétés de Courses, Chatenay Malabry, France.
authors.forename: Y
authors.initials: Y
authors.lastname: Bonnaire
authors.forename: L
authors.initials: L
authors.lastname: Dehennin
authors.forename: P
authors.initials: P
authors.lastname: Plou
authors.forename: P L
authors.initials: PL
authors.lastname: Toutain
mesh_terms: D000818:Animals; D004335:Drug and Narcotic Control; D005260:Female; D005602:France; D006736:Horses; D007273:Injections, Intramuscular; D019966:Substance-Related Disorders / Q000097:blood* / Q000652:urine*; D013739:Testosterone / Q000031:analogs & derivatives / Q000097:blood / Q000652:urine
chemical_list: D013739:Testosterone