Comprehensive Profiling of 6α-Chloro-Testosterone Metabolism in Human Urine Using Gas Chromatography-Mass...

Area of Science:

• Sports Science
• Analytical Chemistry
• Biochemistry

Background:

• 6-chloro-17β-hydroxyandrost-4-en-3-one (6-CT) is a prohibited substance in sports due to its anabolic and antiestrogenic properties.
• Understanding the metabolism of 6-CT is crucial for anti-doping efforts and interpreting athlete biological passport (ABP) data.

Purpose of the Study:

• To investigate the human metabolism of 6-CT using advanced analytical techniques.
• To identify 6-CT metabolites and assess their impact on the endogenous steroid profile and carbon isotope ratio (CIR).

Main Methods:

• Administration of a single oral dose of 6-CT (25 mg) to two volunteers.
• Collection and analysis of urine samples using gas chromatography coupled to mass spectrometry in tandem (GC-MS/MS), time-of-flight (GC-qTOF), and isotopic ratio (GC-C-IRMS).
• Quantification of endogenous steroid profiles and measurement of CIR values, with adjustments for specific gravity.

Main Results:

• Detection of both halogenated and dehalogenated metabolites of 6-CT, consistent with Phase I steroid metabolism.
• Identification of a potential 5β-reduction pathway leading to metabolites with weak or null androgenic activity.
• Observed alterations in the endogenous steroid profile following 6-CT administration.

Conclusions:

• The metabolism of 6-CT in humans involves Phase I reactions, producing various metabolites.
• The impact of 6-CT consumption on the steroid profile warrants careful consideration in the context of the Athlete Biological Passport (ABP).
• Further research may be needed to fully elucidate the long-term effects and detection strategies for 6-CT abuse.