Urinary detection and metabolites profiles of trenbolone and metenolone following trace-level dermal exposure

Recent studies have demonstrated that dermal exposure to anabolic androgenic steroids (AAS) can result in adverse analytical findings (AAFs) in doping controls with a comparably long detectability of the parent compound and/or their metabolites in urine samples. Transdermal absorption is influenced by multiple factors, including physicochemical properties of the substance and solubility; but is largely driven by the degree of exposure, i.e. amount of substance applied. Therefore, this study aimed to investigate the detectability and urinary excretion profiles of trenbolone (TREN) and metenolone (MET) after dermal exposure to microgram quantities of these frequently abused AAS. Controlled excretion studies were conducted with healthy male volunteers, and each participant received a single dose of 50 µg TREN or MET via dermal application to the forearm. Urine samples were collected and analyzed for the parent compounds and their metabolites by liquid chromatography coupled to high resolution tandem mass spectrometry (LC-HRMS/MS). To enhance sensitivity and product ion formation, derivatization with Girard's reagent T was employed for MET and its metabolites. Following administration of transdermal microdoses, both substances and/or their metabolites were detectable in the urine samples of all participants. For TREN, predominantly the established main metabolite epitrenbolone was identified, with maximum concentrations up to 2.6 ng/ml and a detection window of up to three days post-application. Maximum concentrations of MET ranged from 0.1-1.2 ng/ml. Notably, particularly the sulfoconjugated metabolite of MET remained detectable for over a week in one volunteer. Metabolite profiles were compared with those of urine samples obtained after oral administration of the steroids to assess potential differences. Considering the increasing number of alleged transdermal contamination cases, the results provide important analytical data to better assess the plausibility of such claims.