Abstract
RAD140 is a selective androgen receptor modulator which has been abused in sporting competitions. Its use is prohibited by the World Anti-Doping Agency (WADA) for athletes at all times. In addition to its illicit use, adverse analytical findings of RAD140 in doping control samples might result from other scenarios, e.g., the ingestion of contaminated dietary supplements. The differentiation between samples resulting from such contamination scenarios and intentional doping presents a considerable challenge, as little is known about the metabolism and elimination behavior of RAD140 in humans. In this study, six micro-dose excretion studies with five adult male volunteers each were conducted, and urine samples were analyzed by means of LC-HRMS/MS. Multiple metabolites, firstly detected in human urine, are described in this study. The sample preparation included an enzymatic hydrolysis step, which facilitated the estimation of RAD140 concentrations in urine. The elimination profiles and detection times for six metabolites as well as the intact drug are presented. The method was extensively characterized and deemed fit-for-purpose. The metabolite ratios were investigated for their predictive power in estimating the dose of RAD140 intake. The presented data will aid in better case result management in future doping cases involving RAD140.