In vitro metabolism studies of desoxy‐methyltestosterone (DMT) and its five analogues, and in vivo metabolism of desoxy‐vinyltestosterone (DVT) in horses

Abstract

The positive findings of norbolethone in 2002 and tetrahydrogestrinone in 2003 in human athlete samples confirmed that designer steroids were indeed being abused in human sports. In 2005, an addition to the family of designer steroids called 'Madol' [also known as desoxy-methyltestosterone (DMT)] was seized by government officials at the US-Canadian border. Two years later, a positive finding of DMT was reported in a mixed martial arts athlete's sample. It is not uncommon that doping agents used in human sports would likewise be abused in equine sports. Designer steroids would, therefore, pose a similar threat to the horseracing and equestrian communities. This paper describes the in vitro metabolism studies of DMT and five of its structural analogues with different substituents at the 17α position (RH, ethyl, vinyl, ethynyl and H -methyl). In addition, the in vivo metabolism of desoxy-vinyltestosterone (DVT) in horses will be presented. The in vitro studies revealed that the metabolic pathways of DMT and its analogues occurred predominantly in the A-ring by way of a combination of enone formation, hydroxylation and reduction. Additional biotransformation involving hydroxylation of the 17α-alkyl group was also observed for DMT and some of its analogues. The oral administration experiment revealed that DVT was extensively metabolised and the parent drug was not detected in urine. Two in vivo metabolites, derived respectively from (1) hydroxylation of the A-ring and (2) di-hydroxylation together with A-ring double-bond reduction, could be detected in urine up to a maximum of 46 h after administration. Another in vivo metabolite, derived from hydroxylation of the A-ring with additional double-bond reduction and di-hydroxylation of the 17α-vinyl group, could be detected in urine up to a maximum of 70 h post-administration. All in vivo metabolites were excreted mainly as glucuronides and were also detected in the in vitro studies. Copyright © 2015 John Wiley & Sons, Ltd.

In vivo metabolism of the designer anabolic steroid hemapolin in the thoroughbred horse

“…One of the enone metabolites was confirmed as E3 by comparison with a reference material. 28 In this study, the two enone metabolites E2 and E4 were confirmed by comparison with reference materials, and E3 was not observed. This difference could reflect the different starting steroids for two studies, the 3:1 mixture of Δ 2-3 and Δ 3-4 alkene isomers of M used in the in vitro study, or differences between in vitro and in vivo metabolic profiles.…”

“…A previous study of the equine in vitro metabolism of M (used as a 3:1 mixture of Δ 2‐3 and Δ 3‐4 alkene isomers) identified nine equine metabolites after TMS derivatization and GC‐MS/MS analysis, resulting from hydroxylation (2), hydroxylation, and oxidation (enone, 2), dihydroxylation and reduction (2) and trihydroxylation and reduction (3). One of the enone metabolites was confirmed as E3 by comparison with a reference material . In this study, the two enone metabolites E2 and E4 were confirmed by comparison with reference materials, and E3 was not observed.…”

Challenges in detecting substances for equine anti‐doping

“…[57,58] The in vitro metabolism studies of desoxy-methyltestosterone (DMT), widely known as MADOL, and five of its structural analogues with different substituents at the 17α-position (R═H, ethyl, vinyl, ethynyl and H 3 -methyl) of typical steroid structure was studied in equine liver microsomes and the in vivo metabolism of one of the DMT analogues, desoxy-vinyltestosterone (DVT) using GC-MS in the electron ionization (EI) mode with full-scan acquisition was reported. [59] The detection and metabolic investigation of the novel designer steroid, 3-chloro-17α-methyl-5α-androstan-17β-ol, was performed highlighting its efficiency for doping. Due to the potential toxicity of the halogenated steroid, in vitro metabolic investigations of 3α-chloro-17α-methyl-5α-androstan-17β-ol using equine and human S9 liver fractions were performed.…”

“…The in vitro metabolism studies of desoxy‐methyltestosterone (DMT), widely known as MADOL, and five of its structural analogues with different substituents at the 17 α ‐position (R═H, ethyl, vinyl, ethynyl and H 3 ‐methyl) of typical steroid structure was studied in equine liver microsomes and the in vivo metabolism of one of the DMT analogues, desoxy‐vinyltestosterone (DVT) using GC–MS in the electron ionization (EI) mode with full‐scan acquisition was reported …”

A review of designer anabolic steroids in equine sports

“…A summary of the metabolism of these compounds in equine systems in presented below (Table ). The designer steroids desoxyvinyltestosterone (17α‐pregna‐2,20‐dien‐17β‐ol), and Trena (estra‐4,9‐diene‐3,17‐dione) have been studied in equine systems as reviewed by Scarth et al, and are included only briefly in this work.…”