In vitro metabolism of the REV-ERB agonist SR-9009 and subsequent detection of metabolites in associated routine equine plasma and urine doping control samples.

This study delves into the understanding of how the synthetic compound SR-9009, which is often used as a performance-enhancing additive, breaks down in the body, and subsequently, can be detected through doping controls in horses. Their research identified six metabolites of SR-9009 and successfully discovered the presence of these metabolites in sampled horse plasma and urine as potential markers of doping.

Objective and Methodology

• The researchers aimed to understand the in vitro metabolism (the sum of chemical reactions in living organisms) of SR-9009, a synthetic compound frequently available online as a ‘supplement’ product. This compound potentially enhances performance, posing a considerable threat to the integrity of sports, particularly in horseracing where doping control is vital.
• To identify plausible targets for the detection of SR-9009, the team performed a metabolic study with equine liver microsomes (a type of microbody found in cells).

Results

• The study discovered six metabolites, which are the intermediates and products of metabolism. The most significant of these were N-dealkylated metabolites (M1-M3).
• Adding these identified metabolites to high-resolution accurate mass databases led to a positive finding for the N-dealkylated metabolite M1 of SR-9009 in an associated doping sample of plasma and urine.
• Using liquid chromatography-high-resolution mass spectrometry, the researchers validated the presence of the N-dealkylated metabolite (M1) in both plasma and urine samples. Additionally, they identified a minimal concentration of the parent compound (the original molecule, or SR-9009) and extra N-dealkyl metabolites (M2 and M3) in the plasma sample, supporting evidence that the synthetic compound was administered.

Key Findings and Implications

• This study is noted as the first known report of an adverse analytical finding, which refers to a prohibited substance or its metabolites or markers being detected, in a horse’s sample for SR-9009 or its metabolites in relation to doping control.
• These findings provide an enhanced understanding of how SR-9009 operates within the body and provide a basis for detecting this substance in doping samples.
• The identification of these metabolites could potentially help create a more robust doping control system in equine sports, ensuring fair competition and animal welfare.