Detection of urinary metabolites common to structurally related 17α-alkyl anabolic steroids in horses and application to doping tests in racehorses: Methandienone, methandriol, and oxymetholone

Abstract

Methandienone, methandriol, and oxymetholone, which are anabolic steroids possessing 17α-methyl and 17β-hydroxy groups, were developed as oral formulations for therapeutic purposes. However, they have been used in racehorses to enhance racing performance. In humans, it has been reported that structurally related anabolic steroids having the 17α-methyl and 17β-hydroxy groups, including 17α-methyltestosterone, mestanolone, methandienone, methandriol, and oxymetholone, have metabolites in common. In this study, we found that metabolites common to those of 17α- methyltestosterone and mestanolone were detected in horse urine after the administration of oxymetholone, methandienone, and methandriol. Based on analytical data, we confirmed these to be the common metabolites of five structurally related steroids, 17α-methyltestosterone, mestanolone, oxymetholone, methandienone, and methandriol. Furthermore, we detected hitherto unknown urinary metabolites of methandriol and oxymetholone in horses. The parent steroid itself was detected in horse urine after the administration of methandriol, other than metabolites common to 17α-methyltestosterone and mestanolone. On the other hand, the major metabolite of oxymetholone was mestanolone, aside from metabolites presumed to be the stereoisomers of 2-hydroxymethyl-17α-methyl-5α-androstan-3,17β-diol and 2,17α-di(hydroxymethyl)-5α-androstan-3,17β-diol. The simultaneous detection of common metabolites and other main metabolites would help us narrow down the candidate-administered steroid for the doping tests in racehorses.