Preliminary study of the metabolism of 17 alpha-methyltestosterone in horses utilizing gas chromatography-mass spectrometric techniques.

The research article explores the metabolic processes of 17 alpha-methyltestosterone, an anabolic steroid, in horses. The study uncovered different metabolic processes related to the substance, contributing to better methods of confirming the steroids’ presence.

Research Objective and Methodology

• The purpose of this study was to understand the metabolism of 17 alpha-alkyl anabolic steroids, particularly 17 alpha-methyltestosterone, in horses. Prior to this research, this area remains relatively unexplored.
• The team administered a mix of the steroid and its deuteriated analogue orally to the horses. Both compounds were synthesized from dehydroisoandrosterone (DHA), using a Grignard reaction followed by an Oppenauer oxidation.
• After administration, urine extracts from the horses were analyzed using gas chromatography–mass spectrometry (GC-MS). Two techniques were used for this: electron impact (IE) and chemical ionization (CI).

Data Interpretation

• The data interpretation was facilitated by the observation of fragment ions present in the mass spectra.
• The D-ring fragment ions were indicative of 15- or 16-hydroxylation. Observations noted that 16-hydroxy metabolites showed ion pairs at m/z 218/221 and at m/z 231/234, while 15-hydroxy compounds gave the 231/234 ion pair alone.
• Unaltered D-rings reflected fragment ions at m/z 143/146.
• The data revealed the main phase 1 metabolic processes were the partial and complete reduction of the 3-oxo-4-ene group, 15-hydroxylation, 16-hydroxylation, 17-epimerization and hydroxylation at at least two other unknown sites, postulated as the 6 and 11 positions.

Outcome and Relevance of Study

• The study also pointed out the occurrence of phase 2 metabolism, which was common, as shown by the formation of glucuronide and sulfate.
• The findings of this research study add to the understanding of how 17 alpha-alkyl anabolic steroids are metabolized within horses, which has implications for the veterinary and animal sports industries. Confirmation of the presence of these steroids will now be more accurate with the knowledge from this investigation.