Investigations Into the Human Metabolism of Trestolone (7α‐Methyl‐19‐Nortestosterone)

Already in the 1960s, the anabolic properties of Trestolone (7α‐methyl‐19‐nortestosterone, MENT) were investigated in the context of cancer research, and MENT was found to be 10 times more potent regarding its anabolic properties compared to testosterone. The human metabolism of MENT was only investigated once in an antidoping context, and three urinary metabolites were identified, corroborating earlier findings from in vitro and animal experiments. Based on these metabolites, no doping control sample was reported to contain MENT or its metabolites in the last two decades albeit MENT is readily available via online distributors. One reason for the lack of adverse analytical findings in doping controls could be analytical challenges originating from the chromatographic properties of MENT and its urinary metabolites. Therefore, the human metabolism of MENT was reinvestigated employing an excretion study with deuterated MENT and metabolite detection based on hydrogen isotope ratio mass spectrometry in combination with high accuracy/high resolution mass spectrometry. Considering unconjugated, glucuronidated, and sulfated metabolites, 50 potential candidates were detected. In order to identify those metabolites suitable for sports drug testing, three volunteers administered a single oral dose of nondeuterated MENT, and all postadministration samples were investigated using triple quadrupole mass spectrometry‐based determinations routinely employed in doping controls. From the 50 metabolites detected, two showed promising results with respect to their detection windows and suitability under routine measurement conditions. The specificity of the novel metabolites was ensured by the reanalysis of 200 routine doping control samples demonstrating the absence of potential coeluting compounds.