Analytical strategies to detect enobosarm administration in bovines

Selective androgen receptor modulators (SARMs) are a novel class of androgen receptor ligands. They are intended to exhibit the same kind of effects as androgenic drugs, like anabolic steroids, but be much more selective in their action, targeting particular tissues without any undesirable effects on others. While the main applications of these synthetic substances are for therapeutic purposes, they also have a high potential for misuse in veterinary practice and the sporting world. In order to guarantee for consumers with food from animal origin that it is free from any residues of such compounds, analytical strategies are required to ensure safe food and also to enable fair trade between producers. In this context an animal experiment involving bovines administered with enobosarm was conducted to provide the study with biological matrices. Different animal matrices (urine and faeces) were investigated to select the most appropriate matrix for use for control purposes, in terms of metabolite relevance and detection time window. Based on ultra-high-pressure liquid chromatography (UHPLC) with tandem mass spectrometry (LC-MS/MS) this work highlighted the presence of sulfonated and glucuronated-conjugated forms of the molecule in the urine of treated animals. Enobosarm could be detected in urine up to 9 days after the administration when samples underwent phase II hydrolysis. Faeces was demonstrated to be the main matrix of excretion of enobosarm since values up to 500 times higher compared with urine could be detected for 21 days. There was no difference between the kinetic profiles when a deconjugation step was or was not was applied.