Genotype-dependent metabolism of exogenous testosterone - new biomarkers result in prolonged detectability

Characterization and quantitation of a sulfoconjugated metabolite for detection of methyltestosterone misuse and direct identification by LC-MS

Methyltestosterone (MT) is one of the most frequently misused anabolic androgenic steroids detected in doping control analysis. The metabolism of MT in humans leads to several phase І metabolites and their corresponding phase Ⅱ conjugates. Previous studies have postulated the 3α-sulfoconjugate of 17α-methyl-5β-androstane-3α,17β-diol (S2) as principal sulfate metabolite of MT, with a detection window exceeding 10 days. However, a final direct and unambiguous confirmation of the structure of this metabolite is missing until now. In this study, we established an approach to detect and identify S2, using intact analysis by liquid chromatography hyphenated with tandem mass spectrometry (LC-MS/MS) without complex sample pretreatment. An in vitro study yielded the LC-MS/MS reference retention times of all 3-sulfated 17-methylandrostane-3,17-diol diastereomers, allowing for accurate structure assignment of potentially detected metabolites. In an in vivo excretion study with a single healthy male volunteer, the presence of the metabolite S2 was confirmed after a single oral dose of 10 mg MT. The reference standard was chemically synthesized, characterized by accurate mass mass spectrometry (MS) and nuclear magnetic resonance (NMR), and quantified by quantitative NMR (qNMR). Thus, this study finally provides accurate structure information on the S2 metabolite and a direct analytical method for detection of MT misuse. The availability of the reference material is expected to facilitate further evaluation and subsequent analytical method validation in anti-doping research.

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.

Investigations on the in vivo metabolism of 5α-androst-2-en-17-one

RATIONALE

The anabolic steroid 5α-androst-2-en-17-one (2EN) is sold as a prohormone and has been investigated regarding its potential as a steroidal aromatase inhibitor. The administration of 2EN was detected in a doping control sample in 2015, and investigations into its metabolism allowed for the identification and characterization of three urinary metabolites. Unfortunately, the utility of the main metabolite 2β,3α-dihydroxy-5α-androstan-17-one for doping control purposes was hampered under routine doping control conditions due to chromatographic issues, thus warranting further studies on the metabolism of the prohibited substance.

METHODS

The metabolism of 2EN was reinvestigated after oral administration of twofold-deuterated 2EN employing hydrogen isotope ratio mass spectrometry (IRMS) in combination with high-accuracy/high-resolution mass spectrometry. After a single dose of 50 mg of doubly labeled 2EN, urine samples were collected for 9 days. All samples were processed using routine doping control methods for IRMS analysis, and all detected metabolites were further characterized by mass spectrometry-based investigations.

RESULTS

More than 15 different metabolites still containing the deuterium label were detected after administration. The presence of steroids exhibiting a 5β-configuration was unexpected as the administered 2EN features a 5α-configured pharmacophore. Further investigations corroborated a significant impact of the administered 2EN on etiocholanolone and 5β-androstanediol. Seven metabolites of 2EN not present as endogenous compounds were identified as potential candidates for routine doping controls and could be detected for up to 9 days after administration.

CONCLUSIONS

The new metabolites identified in this study enable the detection of the misuse of 2EN for up to 9 days. The conversion of a 5α-steroid to urinary metabolites with 5β-configuration has not been reported so far and should be further investigated.

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.

Sensitive detection of testosterone and testosterone prohormone administrations based on urinary concentrations and carbon isotope ratios of androsterone and etiocholanolone

The testing strategy for the detection of testosterone (T) or T-prohormones is based on the longitudinal evaluation of urinary steroid concentrations accompanied by subsequent isotope ratio mass spectrometry (IRMS)-based confirmation of samples showing atypical concentrations or concentration ratios. In recent years, the IRMS methodology focussed more and more on T itself and on the metabolites of T, 5α- and 5β-androstanediol. These target analytes showed the best sensitivity and retrospectivity, but their use has occasionally been challenging due to their comparably low urinary concentrations. Conversely, the carbon isotope ratios (CIR) of the main urinary metabolites of T, androsterone (A) and etiocholanolone (EITO), can readily be measured even from low urine volumes; those however, commonly offer a lower sensitivity and shorter retrospectivity in uncovering T misuse. Within this study, the CIRs of A and ETIO were combined with their urinary concentrations, resulting in a single parameter referred to as 'difference from weighted mean' (DWM). Both glucuronidated and sulfated steroids were investigated, encompassing a reference population (n = 110), longitudinal studies on three individuals, influence of ethanol in two individuals, and re-analysis of several administration studies including T, dihydrotestosterone, androstenedione, epiandrosterone, dehydroepiandrosterone, and T-gel. Especially DWM calculated for the sulfoconjugated steroids significantly prolonged the detection time of steroid hormone administrations when individual reference ranges were applied. Administration studies employing T encompassing CIR common for Europe (-23.8‰ and -24.4‰) were investigated and, even though for a significantly shorter time period and less pronounced, DWM could demonstrate the exogenous source of T metabolites.

Olympic anti-doping laboratory: the analytical technological road from 2016 Rio De Janeiro to 2021 Tokyo

The summer Olympic Games is the major mega sports event since the first modern era Olympiad, held in Athens, Greece in 1896. International Olympic Committee (IOC) has the responsibility of the organization of the summer and winter Games ensuring the broadcast in all corners of earth. The World Anti-Doping Agency (WADA) is the responsible organization of the fight against doping in sports. IOC and WADA support the event's country WADA Accredited Laboratory to incorporate the maximum of the new analytical technologies to become applicable during the event's antidoping testing. The current study reviewed the last 5 years progresses of the antidoping system with emphasis on the laboratory field.

Recent advances in identifying and utilizing metabolites of selected doping agents in human sports drug testing

Probing for evidence of the administration of prohibited therapeutics, drugs and/or drug candidates as well as the use of methods of doping in doping control samples is a central assignment of anti-doping laboratories. In order to accomplish the desired analytical sensitivity, retrospectivity, and comprehensiveness, a considerable portion of anti-doping research has been invested into studying metabolic biotransformation and elimination profiles of doping agents. As these doping agents include lower molecular mass drugs such as e.g. stimulants and anabolic androgenic steroids, some of which further necessitate the differentiation of their natural/endogenous or xenobiotic origin, but also higher molecular mass substances such as e.g. insulins, growth hormone, or siRNA/anti-sense oligonucleotides, a variety of different strategies towards the identification of employable and informative metabolites have been developed. In this review, approaches supporting the identification, characterization, and implementation of metabolites exemplified by means of selected doping agents into routine doping controls are presented, and challenges as well as solutions reported and published between 2010 and 2020 are discussed.

Long-term stability study and evaluation of intact steroid conjugate ratios after the administration of endogenous steroids

The most frequently detected substances prohibited by the World Anti-Doping Agency (WADA) belong to the anabolic steroids class. The most challenging compounds among this class are the endogenous anabolic steroids, which are detected by quantitative measurement of testosterone (T) and its metabolites with a so-called "steroid profiling" method. The current steroid profile is based on the concentrations and ratios of the sum of free and glucuronidated steroids. Recently, our group developed a steroid profiling method for the detection of three free steroids and 14 intact steroid conjugates, including both the glucuronic acid conjugated and sulfated fraction. The study aimed at evaluating the long-term stability of steroid conjugate concentrations and ratios, and the influence of different endogenous steroids on this extended steroid profile. A single dose of oral T undecanoate (TU), topical T gel, topical dihydrotestosterone (DHT) gel, and oral dehydroepiandrosterone (DHEA) was administered to six healthy male volunteers. One additional volunteer with a homozygote deletion of the UGT2B17 gene (del/del genotype) received a single topical dose of T gel. An intramuscular dose of TU was administered to another volunteer. To avoid fluctuation of steroid concentrations caused by variations in urinary flow rates, steroid ratios were calculated and evaluated as possible biomarkers for the detection of endogenous steroid abuse with low doses. Overall, sulfates do not have substantial additional value in prolonging detection times for the investigated endogenous steroids and administration doses. The already monitored glucuronides were overall the best markers and were sufficient to detect the administered steroids.

Identification of Trenbolone Metabolites Using Hydrogen Isotope Ratio Mass Spectrometry and Liquid Chromatography/High Accuracy/High Resolution Mass Spectrometry for Doping Control Analysis

Trenbolone is a synthetic anabolic-androgenic steroid, which has been misused for performance enhancement in sports. The detection of trenbolone doping in routine sports drug testing programs is complex as methods utilizing gas chromatography/mass spectrometry are complicated by unspecific derivatization products and artifacts, and liquid chromatography/mass spectrometry-based assays have shown to allow for comparably high limits-of-detection only. The number of previously reported metabolites in human urine is limited, and most analytical methods rely on targeting epitrenbolone, trenbolone glucuronide, and epitrenbolone glucuronide. In order to probe for the presence of additional trenbolone metabolites and to re-investigate the metabolism, an elimination study was conducted. One single dose of 10 mg of 5-fold deuterated trenbolone was administered to a healthy male volunteer and urine samples were collected for 30 days. For sample processing, published protocols were combined considering unconjugated, glucuronic acid-, sulfo- and alkaline-labile conjugated steroid metabolites. The sample preparation strategy consisted of solid-phase extractions, liquid-liquid extractions, metabolite de-conjugation, HPLC fractionation, and derivatization. Analytical methods included gas chromatography/thermal conversion/hydrogen isotope ratio mass spectrometry combined with single quadrupole mass spectrometry as well as liquid chromatography/high accuracy/high resolution mass spectrometry of the hydrolyzed and non-hydrolyzed samples. Twenty deuterium-labeled metabolites were identified including glucuronic acid-, sulfo- and potential cysteine-conjugates, and characterized by parallel reaction monitoring experiments yielding corresponding product ion mass spectra. Main metabolites were attributed to trenbolone-diol and potential trenbolone-diketone derivatives excreted as glucuronic acid and sulfo-conjugated analytes with detection windows of 5, respectively 6 days. Further characterization was conducted with pseudo MS3 experiments of the intact conjugates and by comparison of resulting product ion mass spectra with reference material.

Population reference ranges of urinary endogenous sulfate steroids concentrations and ratios as complement to the steroid profile in sports antidoping

The population based Steroid Profile (SP) ratio of testosterone (T) and epitestosterone (E) has been considered as a biomarker approach to detect testosterone abuse in '80s. The contemporary Antidoping Laboratories apply the World Antidoping Agency (WADA) Technical Document (TD) for Endogenous Androgenic Anabolic Steroids (EAAS) in the analysis of SP during their screening. The SP Athlete Biological Passport (ABP) adaptive model uses the concentrations of the total of free and glucuronide conjugated forms of six EAASs concentrations and ratios measured by GC/MS. In the Antidoping Lab Qatar (ADLQ), the routine LC/MS screening method was used to quantitatively estimate the sulfate conjugated EAAS in the same analytical run as for the rest qualitative analytes. Seven sulfate EAAS were quantified for a number of routine antidoping male and female urine samples during screening. Concentrations, statistical parameters and selected ratios for the 6 EAAS, the 6 sulfate EAAS and 29 proposed ratios of concentrations from both EAAS and sulfate EAAS, which potentially used as SP ABP biomarkers, population reference limits and distributions have been estimated after the GC/MSMS analysis for EAAS and LC/Orbitrap/MS analysis for sulfate EAAS.

Steroidomics for highlighting novel serum biomarkers of testosterone doping

Aim: Quantification of testosterone (T) and 5α-dihydrotestosterone serum concentrations proved to be an efficient alternative to urinary steroid profiling for the detection of T doping. In this context, additional serum markers could be discovered by exploratory untargeted steroidomics studies. Results: Endogenous steroid metabolites were monitored by ultra high-performance liquid chromatography coupled to high-resolution mass spectrometry in serum samples collected during a T administration clinical trial. A three-step workflow for accurate review of annotation was used and multifactorial data analysis allowed highlighting promising serum biomarkers. Longitudinal monitoring of selected compounds was performed to assess T abuse detection capabilities. Conclusion: Application of serum steroidomics showed high potential for biomarker discovery of T doping, suggesting longitudinal monitoring of steroid hormones in serum as a significant improvement in detection of endogenous steroids abuse.

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

The introduction of alternative markers to the steroid profile can be an effective approach to improving the screening capabilities for the detection of testosterone (T) misuse. In this work, endogenous steroid sulfates were evaluated as potential markers to detect intramuscular (IM) T administration. Fourteen sulfate metabolites were quantified using mixed-mode solid-phase extraction and analysis by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Urine samples after a single IM injection (100 mg) of T cypionate to six Caucasian and six Asian healthy male volunteers were analyzed. Principal component analysis (PCA) was used to characterize the sample cohort and to obtain the most useful markers for discrimination between pre- and post-administration samples. For Caucasian volunteers, a separation between pre- and post-administration samples was observed in PCA, whereas for Asian volunteers no separation was obtained. Seventeen ratios between sulfate metabolites were selected and further considered. Detection times (DTs) of each marker were evaluated using individual thresholds for each volunteer. The best results were obtained using ratios involving T and epitestosterone (E) sulfates in the denominator. The best marker was the ratio androsterone sulfate/testosterone sulfate (A-S/T-S) which prolonged the DT 1.2-2.1 times in respect to those obtained using T/E ratio in all Caucasian volunteers and 1.3-1.5 times in two Asian volunteers. Other ratios between A-S or etiocholanolone sulfate and E-S, and sulfates of etiocholanolone, dehydroandrosterone or epiandrosterone, and T-S were also found adequate. These ratios improve the DT after IM T administration and their incorporation to complement the current steroid profile is recommended.

Sulfate metabolites improve retrospectivity after oral testosterone administration

The detection of testosterone (T) misuse is performed using the steroid profile that includes concentrations of T and related metabolites excreted free and glucuronoconjugated, and the ratios between them. In this work, the usefulness of 14 endogenous steroid sulfates to improve the detection capabilities of oral T administration has been evaluated. Quantitation of the sulfate metabolites was performed using solid-phase extraction and analysis by liquid chromatography-tandem mass spectrometry. Urine samples were collected up to 144 hours after a single oral dose of T undecanoate (120 mg) to five Caucasian male volunteers. Detection times (DTs) of each marker were estimated using reference limits based on a population study and also monitoring the individual threshold for each volunteer. High inter-individual variability was observed for sulfate metabolites and, therefore, better DTs were obtained using individual thresholds. Using individual threshold limits, epiandrosterone sulfate (epiA-S) improved the DT with respect to testosterone/epitestosterone (T/E) ratio in all volunteers. Androsterone, etiocholanolone, and two androstanediol sulfates also improved DTs for some volunteers. Principal component analysis was used to characterize the sample cohort, obtaining 13 ratios useful for discrimination. These ratios as well as the ratio epiA-S/dehydroepiandrosterone sulfate were further examined. The most promising results were obtained using ratios between sulfates of epiA, androsterone, or androstanediol 1 and E, and also sulfates of epiA or androstanediol 1, and dehydroandrosterone. These selected ratios prolonged the DT of oral T administration up to 144 hours, which corresponded to a significantly higher retrospectivity compared to those obtained using concentrations or the conventional T/E ratio.

Intracrine androgen biosynthesis, metabolism and action revisited

Androgens play an important role in metabolic homeostasis and reproductive health in both men and women. Androgen signalling is dependent on androgen receptor activation, mostly by testosterone and 5α-dihydrotestosterone. However, the intracellular or intracrine activation of C19 androgen precursors to active androgens in peripheral target tissues of androgen action is of equal importance. Intracrine androgen synthesis is often not reflected by circulating androgens but rather by androgen metabolites and conjugates. In this review we provide an overview of human C19 steroid biosynthesis including the production of 11-oxygenated androgens, their transport in circulation and uptake into peripheral tissues. We conceptualise the mechanisms of intracrinology and review the intracrine pathways of activation and inactivation in selected human tissues. The contribution of liver and kidney as organs driving androgen inactivation and renal excretion are also highlighted. Finally, the importance of quantifying androgen metabolites and conjugates to assess intracrine androgen production is discussed.

Epiandrosterone sulfate prolongs the detectability of testosterone, 4-androstenedione, and dihydrotestosterone misuse by means of carbon isotope ratio mass spectrometry

In the course of investigations into the metabolism of testosterone (T) by means of deuterated T and hydrogen isotope ratio mass spectrometry, a pronounced influence of the oral administration of T on sulfoconjugated steroid metabolites was observed. Especially in case of epiandrosterone sulfate (EPIA_S), the contribution of exogenous T to the urinary metabolite was traceable up to 8 days after a single oral dose of 40 mg of T. These findings initiated follow-up studies on the capability of EPIA_S to extend the detection of T and T analogue misuse by carbon isotope ratio (CIR) mass spectrometry in sports drug testing. Excretion study urine samples obtained after transdermal application of T and after oral administration of 4-androstenedione, dihydrotestosterone, and EPIA were investigated regarding urinary concentrations and CIR. With each administered steroid, EPIA_S was significantly depleted and prolonged the detectability when compared to routinely used steroidal target compounds by a factor of 2 to 5. In order to simplify the sample preparation procedure for sulfoconjugated compounds, enzymatic cleavage by Pseudomonas aeruginosa arylsulfatase was tested and implemented into CIR measurements for the first time. Further simplification was achieved by employing multidimensional gas chromatography to ensure the required peak purity for CIR determinations, instead of sample purification strategies using liquid chromatographic fractionation. Taking into account these results that demonstrate the unique and broad applicability of EPIA_S for the detection of illicit administrations of T or T-related steroids, careful consideration of how this steroid can be implemented into routine doping control analysis appears warranted. Copyright © 2017 John Wiley & Sons, Ltd.

Replacing PAPS: In vitro phase II sulfation of steroids with the liver S9 fraction employing ATP and sodium sulfate

In vitro technologies provide the capacity to study drug metabolism where in vivo studies are precluded due to ethical or financial constraints. The metabolites generated by in vitro studies can assist anti-doping laboratories to develop protocols for the detection of novel substances that would otherwise evade routine screening efforts. In addition, professional bodies such as the Association of Official Racing Chemists (AORC) currently permit the use of in-vitro-derived reference materials for confirmation purposes providing additional impetus for the development of cost effective in vitro metabolism platforms. In this work, alternative conditions for in vitro phase II sulfation using human, equine or canine liver S9 fraction were developed, with adenosine triphosphate (ATP) and sodium sulfate in place of the expensive and unstable co-factor 3'-phosphoadenosine-5'-phosphosulfate (PAPS), and employed for the generation of six representative steroidal sulfates. Using these conditions, the equine in vitro phase II metabolism of the synthetic or so-called designer steroid furazadrol ([1',2']isoxazolo[4',5':2,3]-5α-androstan-17β-ol) was investigated, with ATP and Na₂ SO₄ providing comparable metabolism to reactions using PAPS. The major in vitro metabolites of furazadrol matched those observed in a previously reported equine in vivo study. Finally, the equine in vitro phase II metabolism of the synthetic steroid superdrol (methasterone, 17β-hydroxy-2α,17α-dimethyl-5α-androstan-3-one) was performed as a prediction of the in vivo metabolic profile.