Evaluation of epiandrosterone as a long‐term marker of testosterone use

Metabolic profile characterization of voxelotor in human urine based on in vivo and in vitro models for doping control

Voxelotor was approved for the treatment of sickle cell anemia as a potent hemoglobin S polymerization inhibitor. Owing to its ability to affect blood components and its potential to enhance athletic performance, voxelotor was included in the prohibited list issued by the World Anti-Doping Agency in 2023, banning its use both in and out of competition. This study aimed to comprehensively investigate the metabolic profile of voxelotor in human urine and identify suitable metabolites for long-term analytical retrospectivity in doping control. A novel strategy for metabolite identification was established by combining in vivo human administration with isotope labeling-based in vitro metabolism analysis. A single microdose of voxelotor was administered orally to five volunteers, and urine samples were collected for up to 28 days post-administration. Concurrently, in vitro incubation of human liver microsomes with voxelotor and D3-voxelotor was conducted, and the microsomal incubates were analyzed via liquid chromatography-high-resolution mass spectrometry. Targeted metabolite searches in human urine samples and automated nontargeted screening of isotope metabolite ion pairs in incubation samples led to the discovery of 9 phase I metabolites and 23 phase II metabolites. Analysis of the urine excretion curves revealed that 4 metabolites, along with voxelotor, were suitable for long-term anti-doping monitoring, with a detection window exceeding 20 days. Using both in vivo and in vitro metabolic models, this study provides comprehensive insight into the metabolic profile of voxelotor in human urine for the first time, enhancing the capacity for doping screening and extending the retrospectivity of voxelotor detection.

Evaluation of sulfate metabolites as markers of topical testosterone administration in Caucasian and Asian populations

Sulfate metabolites of endogenous anabolic androgenic steroids (EAAS) have been shown to prolong the detection times compared with the conventional urinary markers of the steroid profile for oral and intramuscular administrations of testosterone (T). In this work, the sensitivity of sulfate EAAS markers for the detection of T gel administration has been evaluated in six Caucasian and six Asian male volunteers. Fourteen sulfate metabolites were measured in basal and post-administration samples after multiple doses of T gel (100 mg/day, three consecutive days), and the detection times based on individual thresholds for each volunteer were evaluated. Sulfate concentrations did not show adequate sensitivity, but the results of sulfate ratios were much more promising. Androsterone sulfate/testosterone sulfate (A-S/T-S), epiandrosterone sulfate/epitestosterone sulfate (epiA-S/E-S), epiA-S/T-S, and etiocholanolone sulfate/epitestosterone sulfate (Etio-S/E-S) provided the most consistent detectability for all volunteers and populations, with detection times ranging from 60 to 96 h since the first dose. Additional ratios improved detectability to up to 7 days, but only in particular volunteers. In general, sensitivity was similar to or better than the conventional testosterone/epitestosterone ratio (T/E) of the steroid profile, which further reinforces the conclusion that sulfate EAAS metabolites can be a good complement for the current steroid profile.

δ13 C values of urinary 19-norandrosterone in antidoping samples and potential for adverse findings from boar offal consumption

19-Norandrosterone (19NA) is the preferred urinary target compound to identify doping with nandrolone or related 19-norsteroids. At concentrations between 2.5 and 15 ng/mL, isotope ratio mass spectrometry (IRMS) is required to establish exogenous origin of urinary 19NA. An absolute difference of 3‰ between urinary 19NA and an endogenous reference compound (ERC) constitutes a finding for exogenous origin of 19NA. Over the last 3 years, 77 samples containing urinary 19NA between 2.5 and 15 ng/mL were analyzed at our laboratory. The measured δ13 C values for 19NA ranged from -29.5‰ to -16.8‰. In comparison, the δ13 C values for the corresponding urinary ERCs ranged from -22.4‰ to -16.2‰. Due to the considerable overlap in values between the target compound and the natural range of urinary ERCs, it can be challenging to distinguish between endogenous and exogenous origins of urinary 19NA. In addition, it is well known that consumption of offal from non-castrated pigs can produce 19NA in urine. To determine whether this could cause a positive IRMS finding under the current IRMS positivity criteria, meat from non-castrated boars fed a mixture of corn and soy was consumed by 13 volunteers. Two volunteers produced 19NA findings above 2.5 ng/mL, and the measured isotope values, while inconsistent with documented 19-norsteroid preparations, did meet IRMS positivity criteria. However, these increases in 19NA urinary concentrations were short-lived due to rapid elimination. Timely follow-up collections may help support a claim for dietary exposure when low urinary concentrations of 19NA with pseudo-endogenous isotope values are observed.

Usefulness of serum androgen isotope ratio mass spectrometry (IRMS) to detect testosterone supplementation in women

The detection of testosterone intake is facilitated by monitoring the urinary steroid profile in the athlete biological passport. This technique can be used with confidence to identify target samples for isotope ratio mass spectrometry. Regrettably, most research has been performed on male subjects resulting in a method that does not account for females' steroid concentration and/or variation. This study evaluates the usefulness of the carbon isotope ratio (CIR) in serum of female subjects. Two steroid sulphates are targeted in serum, androsterone and epiandrosterone. Both exhibit statistically significant depletion of their CIR after 10 weeks of daily (10 mg) transdermal testosterone administration. Of the 21 female subjects, samples from six individuals were identified as adverse analytical findings; additionally, four were found atypical considering the serum CIR. The urinary athlete biological passport was not sufficiently sensitive to identify target serum samples for isotope ratio mass spectroscopy. Of the six with a suspicious passport, only two could be confirmed using the serum CIR of androsterone and epiandrosterone. This study shows that CIR analysis in serum cannot be considered the sole confirmatory solution to detect testosterone doping in women due to low sensitivity. However, this analysis has the potential to be used as a complementary method in certain situations to confirm exogenous testosterone in women.

Energy-Resolved Fragmentation Aiding the Structure Elucidation of Steroid Biomarkers

The identification and confirmation of steroid sulfate metabolites in biological samples are essential to various fields, including anti-doping analysis and clinical sciences. Ultra-high-performance liquid chromatography with tandem mass spectrometry (UHPLC-MS/MS) is the leading method for the detection of intact steroid conjugates in biofluids, but because of the inherent complexity of biological samples and the low concentration of many targets of interest, metabolite identification based solely on mass spectrometry remains a major challenge. The confirmation of new metabolites typically depends on a comparison with synthetically derived reference materials that encompass a range of possible conjugation sites and stereochemistries. Herein, energy-resolved collision-induced dissociation (CID) is used as part of UHPLC-HRMS/MS analysis to distinguish between regio- and stereo-isomeric steroid sulfate compounds. This wholly MS-based approach was employed to guide the synthesis of reference materials to unambiguously confirm the identity of an equine steroid sulfate biomarker of testosterone propionate administration.

Androgens, sports, and detection strategies for anabolic drug use

For decades, anabolic androgenic agents have represented the substance class most frequently observed in doping control samples. They comprise synthetic and pseudoendogenous anabolic androgenic steroids and other, mostly non-steroidal compounds with (presumed) positive effects on muscle mass and function. While exogenous substances can easily be detected by gas/liquid chromatography and mass spectrometry, significantly more complex methodologies including the longitudinal monitoring of individual urinary steroid concentrations/ratios and isotope ratio mass spectrometry are required to provide evidence for the exogenous administration of endogenous compounds. This narrative review summarizes the efforts made within the last 5 years to further improve the detection of anabolic agents in doping control samples. Different approaches such as the identification of novel metabolites and biomarkers, the acquisition of complementary mass spectrometric data, and the development of new analytical strategies were employed to increase method sensitivity and retrospectivity while simultaneously reducing method complexity to facilitate a higher and faster sample throughput.

Detection of testosterone microdosing in healthy females

The ready detectability of synthetic androgens by mass spectrometry (MS)-based antidoping tests has reoriented androgen doping to using testosterone (T), which must be distinguished from its endogenous counterpart making detection of exogenous T harder. We investigated urine and serum steroid and hematological profiling individually and combined to determine the optimal detection model for T administration in women. Twelve healthy females provided six paired blood and urine samples over 2 weeks prior to treatment consisting of 12.5-mg T in a topical transdermal gel applied daily for 7 days. Paired blood and urine samples were then obtained at the end of treatment and Days 1, 2, 4, 7, and 14 days later. Compliance with treatment and sampling was high, and no adverse effects were reported. T treatment significantly increased serum and urine T, serum dihydrotestosterone (DHT), urine 5α-androstane-3α,17β-diol (5α-diol) epitestosterone (E), and urine T/E ratio with a brief window of detection (2-4 days) as well as total and immature (medium and high fluorescence) reticulocytes that remained elevated over the full 14 posttreatment days. Carbon isotope ratio MS and the OFF score and Abnormal Blood Profile score (ABPS) were not discriminatory. The optimal multivariate model to identify T exposure combined serum T, urine T/E ratio with three hematological variables (% high fluorescence reticulocytes, mean corpuscular hemoglobin, and volume) with the five variables providing 93% correct classification (4% false positive, 10% false negatives). Hence, combining select serum and urine steroid MS variables with reticulocyte measures can achieve a high but imperfect detection of T administration to healthy females.

HepG2 as promising cell-based model for biosynthesis of long-term metabolites: Exemplified for metandienone

In order to detect the abuse of substances in sports, the knowledge of their metabolism is of undisputable importance. As in vivo administration of compounds faces ethical problems and might even not be applicable for nonapproved compounds, cell-based models might be a versatile tool for biotransformation studies. We coincubated HepG2 cells with metandienone and D₃ -epitestosterone for 14 days. Phase I and II metabolites were analyzed by high-performance liquid chromatography (HPLC)-tandem mass spectrometry and confirmed by gas chromatography-mass spectrometry (GC-MS). The metandienone metabolites formed by HepG2 cells were comparable with those renally excreted by humans. HepG2 cells also generated the two long-term metabolites 17β-hydroxymethyl-17α-methyl-18-nor-androst-1,4,13-trien-3-one and 17α-hydroxymethyl-17β-methyl-18-nor-androst-1,4,13-trien-3-one used in doping analyses, though in an inverse ratio compared with that observed in human urine. In conclusion, we showed that HepG2 cells are suitable as model for the investigation of biotransformation of androgens, especially for the anabolic androgenic steroid metandienone. They further proved to cover phase I and II metabolic pathways, which combined with a prolonged incubation time with metandienone resulted in the generation of its respective long-term metabolites known from in vivo metabolism. Moreover, we showed the usability of D₃ -epitestosterone as internal standard for the incubation. The method used herein appears to be suitable and advantageous compared with other models for the investigation of doping-relevant compounds, probably enabling the discovery of candidate metabolites for doping analyses.

A uniform sample preparation procedure for gas chromatography combustion isotope ratio mass spectrometry for all human doping control relevant anabolic steroids using online 2/3-dimensional liquid chromatography fraction collection

Androgenic anabolic steroids are the most misused substances in sports because of their performance-enhancing effects. Often synthetic analogues of endogenously present steroids are administered. To determine their endogenous or exogenous origin, Gas Chromatography Combustion Isotope Ratio Mass Spectrometry (GC-C-IRMS) is used in the field of doping control. Compounds subjected to IRMS analysis must be interference-free, with liquid chromatography fraction collection (HPLC-FC) being the crucial clean-up step. However, this clean-up is challenging, particularly for compounds present at low concentrations in samples with pronounced matrix effects. The compounds of interests for IRMS analyses in doping control are testosterone (T) and its main metabolites (androsterone, etiocholanolone, 5α-androstane-3α,17β-diol, 5β-androstane-3α,17β-diol), epitestosterone, 19-norandrosterone (19-NA), boldenone (B) and its main metabolite (BM), formestane (F) and 6αOH-androstenedione (6aOHADION). Currently, the available methods only deal with a selection of the above-mentioned compounds. Some of these compounds (e.g., 19-NA, B, BM, 6aOHADION) are present in very low concentrations, requiring an extensive and dedicated sample clean-up, and this makes it challenging to develop a universal clean-up procedure. Many of these methods require different and multiple offline HPLC-FC setups, which are labour-intensive and time-consuming. That is problematic during, e.g., large sports events, where reporting time is limited (e.g., 72 h). Therefore, in the current work, we developed a uniform online 2D/3D HPLC-FC method, capable of purifying all relevant target compounds in a single run, leading to the fastest clean-up procedure so far (i.e., 31 min for T and its main metabolites; 46 min for 19-NA, F and 6aOHADION; 48 min for B and BM).

Re-evaluation of combined ((ES/EG)/(TS/TG)) ratio as a marker of testosterone intake in men

To detect doping with pseudo-endogenous anabolic steroids in sports, a urinary steroid profile with glucuronidated plus unconjugated androgens is used. In addition to analyze androgen glucuronide metabolites, it can be of interest to also include sulfate metabolites in the urinary steroid profile. The combined ratios of epitestosterone sulfate/epitestosterone glucuronide to the ratios of testosterone sulfate/testosterone glucuronide ((ES/EG)/(TS/TG)) have previously been investigated as a complementary biomarker for testosterone doping. In this restudy, the aim was to evaluate this biomarker in a larger study sample population. A single dose of 500-mg testosterone enanthate was administered to 54 healthy male volunteers. Urine was collected prior to (Day 0) administration and throughout 15 days and analyzed for the sulfate and glucuronide conjugates of testosterone and epitestosterone. The results show that the combined ratio increased to a larger extent than the traditional T/E ratio in all subjects. This increase was independent on UGT2B17 gene polymorphism. Moreover, a delayed peak of the combined ratio was observed in ~60% of the participants. The results confirm that complementary analyses of the sulfate metabolites may be a useful approach to detect testosterone doping in men.

Evaluation of blood parameters by linear discriminant models for the detection of testosterone administration

The steroidal module of the Athlete Biological Passport (ABP) has been used since 2014 for the longitudinal monitoring of urinary testosterone and its metabolites to identify samples suspicious for the use of synthetic forms of Endogenous Anabolic Androgenic Steroids (EAAS). Multiple recent studies have suggested that monitoring of blood parameters may provide enhanced detectability of exogenous testosterone administration. Transdermal and intramuscular testosterone administration studies were carried out in 15 subjects, and the effect on blood steroidal levels, hematological parameters, and gonadotropins was evaluated. Serum testosterone and dihydrotestosterone levels increased while gonadotropin levels were suppressed after administration. A modest increase in reticulocytes was also observed. The blood parameters that were responsive to the administrations were combined into several linear discriminant models targeting both administration (on) and washout (off) phases. The models were effective in detecting the large dose intramuscular administration but were less successful in the detection of the lower dose transdermal application. The blood profiling models may provide complementary value but do not appear to be substantially more advantageous than longitudinal urinary profiling.