Investigations on the in vivo metabolism of 5α-androst-2-en-17-one.

Abstract

The anabolic steroid 5α-androst-2-en-17-one (2EN) is sold as a prohormone and has been investigated regarding its potential as a steroidal aromatase inhibitor. The administration of 2EN was detected in a doping control sample in 2015, and investigations into its metabolism allowed for the identification and characterization of three urinary metabolites. Unfortunately, the utility of the main metabolite 2β,3α-dihydroxy-5α-androstan-17-one for doping control purposes was hampered under routine doping control conditions due to chromatographic issues, thus warranting further studies on the metabolism of the prohibited substance. The metabolism of 2EN was reinvestigated after oral administration of twofold-deuterated 2EN employing hydrogen isotope ratio mass spectrometry (IRMS) in combination with high-accuracy/high-resolution mass spectrometry. After a single dose of 50 mg of doubly labeled 2EN, urine samples were collected for 9days. All samples were processed using routine doping control methods for IRMS analysis, and all detected metabolites were further characterized by mass spectrometry-based investigations. More than 15 different metabolites still containing the deuterium label were detected after administration. The presence of steroids exhibiting a 5β-configuration was unexpected as the administered 2EN features a 5α-configured pharmacophore. Further investigations corroborated a significant impact of the administered 2EN on etiocholanolone and 5β-androstanediol. Seven metabolites of 2EN not present as endogenous compounds were identified as potential candidates for routine doping controls and could be detected for up to 9days after administration. The new metabolites identified in this study enable the detection of the misuse of 2EN for up to 9days. The conversion of a 5α-steroid to urinary metabolites with 5β-configuration has not been reported so far and should be further investigated.