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

This research examines how desoxy-methyltestosterone (DMT) and its five analogues break down in a laboratory environment, while desoxy-vinyltestosterone (DVT) is broken down inside a horse’s body. The goal is to understand how these substances, known as designer steroids, are processed and how long they remain detectable, aiding in the detection and deterrence of doping in sports, particularly horse racing.

Overview of Designer Steroids

• Designer steroids such as desoxy-methyltestosterone (DMT) have highlighted the threat of drug abuse in sports. As these substances are often modified versions of known steroids, they can be difficult to detect through standard testing procedures.
• These steroids have been found in human athletes and there’s reasonable cause to suspect similar abuse in equine sports. This research aims to understand their metabolism both in vitro (in a controlled lab environment) and in vivo (inside an organism, in this case, horses), in order to help establish better testing methods.

In Vitro Metabolism

• DMT and its five structural analogues (variations with different substituents) were examined in vitro. The process observed how these substances metabolize, focusing primarily on the changes to their A ring, a part of the steroid’s structure.
• The research found that the metabolic pathways of DMT and its analogues predominantly occurred in the A-ring through a process involving enone formation, hydroxylation, and reduction. Additional biotransformation involving hydroxylation of the 17α-alkyl group was also noted in DMT and some of its analogues.

In Vivo Metabolism in Horses

• The study then examined the administration of desoxy-vinyltestosterone (DVT) in horses to study how it’s metabolized in a living organism.
• Results indicate that DVT was heavily metabolised within horses’ bodies and no traces of the parent drug were detected in their urine.
• The investigation found two in vivo metabolites (substances resulting from metabolism) that originated from the alteration of the A-ring and could be detected up to 46 hours after administration.
• Another metabolite, resulting from further alterations to the A-ring and the 17α-vinyl group, could be detected in urine up to 70 hours post-administration.

Final Observations

• All the detected in vivo metabolites were mainly excreted as glucuronides (a type of conjugated metabolite).
• These metabolites were also observed in the prior in vitro studies, proving important parallels in how these substances are handled in the lab and in an organism’s body.

The findings of this research will be fundamental for testing and detecting designer steroid use in sporting events, particularly within horse racing, ensuring fair and safe competition.