Selective androgen receptor modulators: comparative excretion study of bicalutamide in bovine urine and faeces Dante Rojas, a,b Gaud Dervilly-Pinel, a * Nora Cesbron, a Mylène Penot, a Alexandre Sydor, a Stéphanie Prévost a and Bruno Le Bizec a Besides their development for therapeutic purposes, non-steroidal selective androgen receptor modulators (non-steroidal SARMs) are also known to impact growth-associated pathways as ligands of androgenic receptors (AR). They present a potential for abuse in sports and food-producing animals as an interesting alternative to anabolic androgenic steroids (AAS). These compounds are easily available and could therefore be (mis)used in livestock production as growth promoters. To prevent such practices, dedi- cated analytical strategies should be developed for specific and sensitive detection of these compounds in biological matrices. The present study focused on Bicalutamide, a non-steroidal SARM used in human treatment of non-metastatic prostate cancer because of its anti-androgenic activity exhibiting no anti-anabolic effects. To select the most appropriate matrix to be used for control purposes, different animal matrices (urine and faeces) have been investigated and SARM metabolism studied to highlight relevant metabolites of such treatments and establish associated detection time windows. The aim of this work was thus to compare the urinary and faecal eliminations of bicalutamide in a calf, and investigate phase I and II metabolites. The results in both matrices showed that bicalutamide was very rapidly and mainly excreted under its free form. The concentration levels were observed as higher in faeces (ppm) than urine (ppb); although both matrices were assessed as suitable for residue control. The metabolites found were consistent with hydroxylation (phase I reaction) combined or not with glucuronidation and sulfation (phase II reactions). Copyright © 2016 John Wiley & Sons, Ltd. Keywords: SARMs; metabolism; LC-MS/MS; conjugated metabolites Introduction Because of their aptitude to act like agonist ligands of androgenic receptors (AR), anabolic androgenic steroids (AAS) exhibit strong anabolic effects in muscles and bones. [1–3] Their use is of interest in human medicine for the treatment of catabolic and wasting muscle states caused by age or some diseases (hypogonadism, AIDS, or cancer-related muscle wasting). However, as AAS present undesirable physicochemical and pharmacokinetic properties, such as low absorption rate for oral administration, short time actions, and negative effects in human health (cardiovascular system, androgenic tissues, and in some cases, hepatic toxicity), [4–6] synthetic alternatives were produced to mitigate these adverse effects. In particular, selective androgen receptor modulators (SARMs) have been produced as a novel class of non-steroidal AR ligands. [7] Known since 1998, [8] they have been investigated for therapeutic properties in cachexia treatment since 2005. [2] SARMs action is directed at AR of muscles (growth and strength) and bones (development). [6,9] The ideal non-steroidal SARMs advantages are tissue-selectivity, good performance to oral administration with long time activity, and low toxicity. [6,10,11] Several chemical structures have been developed as non-steroidal SARMs: quinolone analogues, hydantoin analogues, tetrahidro-quinolone analogues, and aryl-propionamide analogues [1,6] SARMs belonging to the aryl-propionamide group have been the first ones to show an interesting agonistic activity with a tissue-selective action in the ste- roidal signalling pathway. [1,12–14] While SARMs are on the World Anti-Doping Agency (WADA) list of prohibited substances, [4] cases of human doping and misuse by athletes are reported from time to time. [15–17] SARMs may also exhibit a high potential for misuse in animal husbandry as growth promoters to increase weight gain, improve carcass quality, and reduce production costs. [7] While in Europe, growth promoters have been banned for use in food-producing animals since 1988 (Council Directive 88/146/EEC prohibiting the use livestock farming of certain substances having a hormonal action 1988), strategies to detect potential SARMs misuse in livestock production are urgently required to guarantee consumers of food from animal origin free of any residues of such compounds. Efficient analytical strategies to detect the use of SARMs have already been proposed and while main developments have been realized in the human anti-doping arena, few applica- tions are now available in food producing animals. [18,19] Since these compounds have recently emerged, they have not been * Correspondence to: Gaud Dervilly-Pinel, LUNAM Université, Oniris, Laboratoire d’Etude des Résidus et Contaminants dans les Aliments (LABERCA), Nantes, F-44307, France. E-mail: gaud.dervilly@oniris-nantes.fr a LUNAM Université, Oniris, Laboratoire d’Etude des Résidus et Contaminants dans les Aliments (LABERCA), Nantes, France b Instituto Tecnología de Alimentos (ITA), Centro de Investigación de Agroindustria (CIA), Instituto Nacional de Tecnología Agropecuaria (INTA), CC77Morón, Argentina Drug Test. Analysis (2016) Copyright © 2016 John Wiley & Sons, Ltd. Research article Drug Testing and Analysis Received: 12 July 2016 Revised: 7 October 2016 Accepted: 7 October 2016 Published online in Wiley Online Library (www.drugtestinganalysis.com) DOI 10.1002/dta.2113