Comparison of in vitro approaches for predicting the metabolism of the selective androgen receptor modulator RAD140.

The identification of metabolites allows for the expansion of possible targets for anti-doping analysis. Especially for novel substances such as selective androgen receptor modulators (SARMs), information on metabolic fate is scarce. Novel approaches such as the organ on a chip technology may provide a metabolic profile that resembles human in vivo samples more closely than approaches that rely on human liver fractions only. In this study, the SARM RAD140 was metabolized by means of subcellular human liver fractions, human liver spheroids in an organ on a chip platform, and electrochemical (EC) conversion. The resulting metabolites were analyzed with LC-HRMS/MS and compared to a human doping control urine sample that yielded an adverse analytical finding for RAD140. A total of 16 metabolites were detected in urine, while 14, 13, and 7 metabolites were detected in samples obtained from the organ on a chip experiment, the subcellular liver fraction, and EC experiments, respectively. All tested techniques resulted in the detection of RAD140 metabolites. In the organ on a chip samples, the highest number of metabolites were detected. The subcellular liver fractions and organ on a chip techniques are deemed complementary to predict metabolites of RAD140, as both techniques produce distinct metabolites that are also found in an anonymized human in vivo urine sample.

Dried blood spots for doping controls-Development of a comprehensive initial testing procedure with fully automated sample preparation.

Currently, primarily urine, whole blood and serum samples are analyzed for doping-relevant substances in professional sports, but recently dried blood spots (DBS) have been introduced as complementary matrix, offering advantageous features, e.g. a minimally invasive sampling procedure. In order to cope with the increased application of DBS, a comprehensive initial testing procedure (ITP) was developed, optimized and validated, comprising a total of 233 substances representing all groups on the World Anti-Doping Agency's (WADA's) Prohibited List. The sample preparation was conducted by employing a fully automated system using an efficient flow-through extraction of a 4 mm diameter spot followed by LC-HRMS/MS analysis. The procedure was successfully validated in terms of selectivity, limit of detection, reproducibility, carryover and robustness with respect to an alternative manual sample preparation, an alternative dried blood collection device and the sample extract stability, and was thus found to meet the required criteria of the relevant guidelines published by WADA for routine application. As a proof-of-concept, DBS samples were analyzed after the administration of the glucocorticoids prednisone and dexamethasone, as well as the stimulant pseudoephedrine and the beta-blocker propranolol. All substances were detected in post-administration samples for at least 4 h and up to 24 h after intake, depending on the collection time period, using the developed testing procedure. In particular, for substances that are only banned in-competition, data obtained from DBS samples can be useful for the interpretation of adverse analytical findings. In conclusion, the developed ITP accounts for the anticipated increasing relevance of DBS in anti-doping analysis in the future and provides a foundation for optimized approaches for specific substance classes.

Investigations into the elimination profiles and metabolite ratios of micro-dosed selective androgen receptor modulator LGD-4033 for doping control purposes.

LGD-4033 (ligandrol) is a selective androgen receptor modulator (SARM), which is prohibited in sports by the World Anti-Doping Agency (WADA) and led to 62 adverse analytical findings (AAFs) in 2019. But not only deliberate doping with LGD-4033 constitutes a problem. In the past years, some AAFs that concerned SARMs can be attributed to contaminated dietary supplements (DS). Thus, the urgency to develop methods to differentiate between inadvertent doping and abuse of SARMs to benefit from the performance-enhancing effect of the compound in sports is growing. To gain a better understanding of the metabolism and excretion patterns of LGD-4033, human micro-dose excretion studies at 1, 10, and 50 µg LGD-4033 were conducted. Collected urine samples were prepared for analysis using enzymatic hydrolysis followed by solid-phase extraction and analyzed via LC-HRMS/MS. Including isomers, a total of 15 phase I metabolites were detected in the urine samples. The LC-HRMS/MS method was validated for qualitative detection of LGD-4033, allowing for a limit of detection (LOD) of 8 pg/mL. The metabolite M1, representing the epimer of LGD-4033, was synthesized and the structure elucidated by NMR spectroscopy. As the M1/LGD-4033 ratio changes over time, the ratio and the approximate LGD-4033 concentration can contribute to estimating the time point of drug intake and dose of LGD-4033 in doping control urine samples, which is particularly relevant in anti-doping result management.

Mass spectrometry in sports drug testing-Analytical approaches and the athletes' exposome.

Test methods in anti-doping, most of which rely on the most modern mass spectrometric instrumentation, undergo continuous optimization in order to accommodate growing demands as to comprehensiveness, sensitivity, retrospectivity, cost-effectiveness, turnaround times, etc. While developing and improving analytical approaches is vital for appropriate sports drug testing programs, the combination of today's excellent analytical potential and the inevitable exposure of humans to complex environmental factors, specifically chemicals and drugs at the lowest levels, has necessitated dedicated research, particularly into the elite athlete's exposome. Being subjected to routine doping controls, athletes frequently undergo blood and/or urine tests for a plethora of drugs, chemicals, corresponding metabolic products, and various biomarkers. Due to the applicable anti-doping regulations, the presence of prohibited substances in an athlete's organism can constitute an anti-doping rule violation with severe consequences for the individual's career (in contrast to the general population), and frequently the question of whether the analytical data can assist in differentiating scenarios of 'doping' from 'contamination through inadvertent exposure' is raised. Hence, investigations into the athlete's exposome and how to distinguish between deliberate drug use and potential exposure scenarios have become a central topic of anti-doping research, aiming at supporting and consolidating the balance between essential analytical performance characteristics of doping control test methods and the mandate of protecting the clean athlete by exploiting new strategies in sampling and analyzing specimens for sports drug-testing purposes.

Simplifying and expanding the screening for peptides <2 kDa by direct urine injection, liquid chromatography, and ion mobility mass spectrometry.

The analysis of low-molecular-mass peptides in doping controls has become a mandatory aspect in sports drug testing and, thus, the number of samples that has to be tested for these analytes has been steadily increasing. Several peptides <2 kDa with performance-enhancing properties are covered by the list of prohibited substances of the World Anti-Doping Agency including Desmopressin, LH-RH, Buserelin, Triptorelin, Leuprolide, GHRP-1, GHRP-2, GHRP-3, GHRP-4, GHRP-5,GHRP-6, Alexamorelin, Ipamorelin, Hexarelin, ARA-290, AOD-9604, TB-500 and Anamorelin. With the presented method employing direct urine injection into a liquid chromatograph followed by ion-mobility time-of-flight mass spectrometry, a facile, specific and sensitive assay for the aforementioned peptidic compounds is provided. The accomplished sensitivity allows for limits of detection between 50 and 500 pg/mL and thus covers the minimum required performance level of 2 ng/mL accordingly. The method is precise (imprecision <20%) and linear in the estimated working range between 0 and 10 ng/mL. The stability of the peptides in urine was tested, and -20°C was found to be the appropriate storage temperature for sports drug testing. Finally, proof-of-concept was shown by analysing elimination study urine samples collected from individuals having administered GHRP-6, GHRP-2, or LHRH.

"Dilute-and-inject" multi-target screening assay for highly polar doping agents using hydrophilic interaction liquid chromatography high resolution/high accuracy mass spectrometry for sports drug testing.

In the field of LC-MS, reversed phase liquid chromatography is the predominant method of choice for the separation of prohibited substances from various classes in sports drug testing. However, highly polar and charged compounds still represent a challenging task in liquid chromatography due to their difficult chromatographic behavior using reversed phase materials. A very promising approach for the separation of hydrophilic compounds is hydrophilic interaction liquid chromatography (HILIC). Despite its great potential and versatile advantages for the separation of highly polar compounds, HILIC is up to now not very common in doping analysis, although most manufacturers offer a variety of HILIC columns in their portfolio. In this study, a novel multi-target approach based on HILIC high resolution/high accuracy mass spectrometry is presented to screen for various polar stimulants, stimulant sulfo-conjugates, glycerol, AICAR, ethyl glucuronide, morphine-3-glucuronide, and myo-inositol trispyrophosphate after direct injection of diluted urine specimens. The usage of an effective online sample cleanup and a zwitterionic HILIC analytical column in combination with a new generation Hybrid Quadrupol-Orbitrap® mass spectrometer enabled the detection of highly polar analytes without any time-consuming hydrolysis or further purification steps, far below the required detection limits. The methodology was fully validated for qualitative and quantitative (AICAR, glycerol) purposes considering the parameters specificity; robustness (rRT < 2.0%); linearity (R > 0.99); intra- and inter-day precision at low, medium, and high concentration levels (CV < 20%); limit of detection (stimulants and stimulant sulfo-conjugates < 10 ng/mL; norfenefrine; octopamine < 30 ng/mL; AICAR < 10 ng/mL; glycerol 100 µg/mL; ETG < 100 ng/mL); accuracy (AICAR 103.8-105.5%, glycerol 85.1-98.3% at three concentration levels) and ion suppression/enhancement effects.

Urinary metabolites indicative of the administration of hypoxen monitored by liquid chromatography-high resolution/accurate mass tandem mass spectrometry.

Hypoxen, a poly(dihydroxyphenylene) thiosulfonate-based drug, has been investigated concerning its effect on mitochondrial respiration and the utilization of lactate, especially in the context of strenuous exercise. Since 2023, patterns of use regarding hypoxen amongst the athletic population are monitored by the World Anti-Doping Agency (WADA) and its accredited anti-doping laboratories, necessitating information on suitable urinary markers indicative of the administration of hypoxen. In this exploratory study, urine samples collected post-administration of 1.5 and 2.0 g of hypoxen were analyzed by means of liquid chromatography-high resolution/high mass accuracy (tandem) mass spectrometry, which allowed for the identification of eight analytes that were plausibly attributable to metabolites of hypoxen. The identified species were assigned to the unconjugated species of S-(2,2',5,5'-tetrahydroxy-[1,1'-biphenyl]-3-yl) sulfurothioate and its glucuronide and additional tentatively identified analytes comprising a mercaptobenzene core structure. Including the identified markers into routine doping control analytical procedures enabled the detection of hypoxen use in athletes' doping control samples, thus contributing relevant information to WADA's monitoring program.

Determination of urinary deanol-N-oxide excretion profiles after ingestion of nutritional supplements containing deanol.

2-(Dimethylamino)ethan-1-ol (Deanol) is a widely produced chemical used by both industry and consumers in a variety of applications. Meclofenoxate, a stimulant classified on the World Anti-Doping Agency Prohibited List, metabolizes into deanol and, presumably, its main metabolite deanol-N-oxide. Hence, using liquid chromatography-tandem mass spectrometry, a quantitative detection method for deanol-N-oxide in urine was developed. Subsequently, the urinary excretion of deanol-N-oxide after oral application of 130 mg of deanol was determined in six volunteers, and urine samples of a cohort of 180 male and female athletes from different sports were analyzed. In addition, urinary deanol-N-oxide was determined in an exploratory study with one volunteer ingesting 250 mg of meclofenoxate. The developed test method allowed for limits of detection and quantification for deanol-N-oxide at 0.05 and 0.15 µg/mL, respectively. Urinary deanol-N-oxide cmax levels were found between 100 and 250 µg/mL 2-5 h post-administration of 130 mg of deanol. Similarly, urine samples collected after the administration of 250 mg of meclofenoxate exhibited cmax levels of 115 µg/mL. In contrast, deanol-N-oxide urine concentrations of pre-administration specimens and 180 routine doping control urine sample were between 0.3 and 1.3 µg/mL and below limit of quantification and 1.8 µg/mL, respectively. The study suggests that the use of deanol and meclofenoxate results in significantly elevated urinary deanol-N-oxide levels. Whether or not monitoring deanol-N-oxide in doping controls can support decision-making processes concerning the detection of meclofenoxate use necessitates further investigations taking into consideration the elimination kinetics of 4-chlorophenoxyacetic acid, the main metabolite of meclofenoxate, and deanol-N-oxide.

Human In Vivo Metabolism and Elimination Behavior of Micro-Dosed Selective Androgen Receptor Modulator RAD140 for Doping Control Purposes.

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.

Meldonium residues in milk: A possible scenario for inadvertent doping in sports?

Lately, the veterinary drug Emidonol® has been discussed as a possible scenario for inadvertent doping in sports. Emidonol® is approved for use in livestock breeding, exhibiting antihypoxic and weak sedative effects. The veterinary drug rapidly dissociates into meldonium, a substance prohibited in sports, and is excreted largely in its unchanged form into urine. To investigate if residues of meldonium in edible produce may result in adverse analytical findings in sports drug testing, a pilot study was conducted with three volunteers consuming a single dose of 100 ml meldonium-spiked milk at a concentration of 500 ng/ml (Study 1), and multiple doses of 100 ml of meldonium-spiked milk (500 ng/ml) on five consecutive days (Study 2). In the single dose study, urinary meldonium concentrations peaked between 2 and 6 h post-administration with maximum values of 7.5 ng/ml, whereas maximum meldonium concentrations of 18.6 ng/ml were determined after multiple doses 4 h post-administration. All samples were analyzed using an established and validated protocol based on HILIC-HRMS/MS.

Mass spectrometric characterization of urinary hydrafinil metabolites for routine doping control purposes.

Little information on the human metabolism and urinary elimination of hydrafinil (9-fluorenol) exists. In order to support preventive anti-doping activities concerning compounds such as hydrafinil, a pilot elimination study was conducted with three healthy male volunteers receiving a single oral dose of 50 mg of hydrafinil. Urine samples were collected prior to and up to 72-h post-administration and were subjected to both gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry, which allowed for the identification of the intact drug as well as Phase I and Phase II metabolites, primarily hydroxylated and/or glucuronidated or sulfo-conjugated hydrafinil. The identity of these metabolites was corroborated by high-resolution/high-accuracy tandem mass spectrometry, and the applicability of routine doping control workflows for the detection of hydrafinil and its main metabolites was assessed. Therefore, two findings of hydrafinil and its metabolites were recorded, which concerned out-of-competition doping control samples and, hence, were not pursued with confirmatory analyses. Yet, the initial testing procedure results indicate that hydrafinil might require consideration in sports drug testing programs to ensure its detection, if classified as prohibited by the World Anti-Doping Agency (WADA).

Organ-on-a-chip: Determine feasibility of a human liver microphysiological model to assess long-term steroid metabolites in sports drug testing.

A fundamental challenge in preventive doping research is the study of metabolic pathways of substances banned in sport. However, the pharmacological predictions obtained by conventional in vitro or in vivo animal studies are occasionally of limited transferability to humans according to an inability of in vitro models to mimic higher order system physiology or due to various species-specific differences using animal models. A more recently established technology for simulating human physiology is the "organ-on-a-chip" principle. In a multichannel microfluidic cell culture chip, 3-dimensional tissue spheroids, which can constitute artificial and interconnected microscale organs, imitate principles of the human physiology. The objective of this study was to determine if the technology is suitable to adequately predict metabolic profiles of prohibited substances in sport. As model compounds, the frequently misused anabolic steroids, stanozolol and dehydrochloromethyltestosterone (DHCMT) were subjected to human liver spheroids in microfluidic cell culture chips. The metabolite patterns produced and circulating in the chip media were then assessed by LC-HRMS/(MS) at different time points of up to 14 days of incubation at 37°C. The overall profile of observed glucurono-conjugated stanozolol metabolites excellently matched the commonly found urinary pattern of metabolites, including 3'OH-stanozolol-glucuronide and stanozolol-N-glucuronides. Similarly, but to a lower extent, the DHCMT metabolic profile was in agreement with phase-I and phase-II biotransformation products regularly seen in postadministration urine specimens. In conclusion, this pilot study indicates that the "organ-on-a-chip" technology provides a high degree of conformity with traditional human oral administration studies, providing a promising approach for metabolic profiling in sports drug testing.

Stanozolol-N-glucuronide metabolites in human urine samples as suitable targets in terms of routine anti-doping analysis.

The exogenous anabolic-androgenic steroid (AAS) stanozolol stays one of the most detected substances in professional sports. Its detection is a fundamental part of doping analysis, and the analysis of this steroid has been intensively investigated for a long time. This contribution to the detection of stanozolol doping describes for the first time the unambiguous proof for the existence of 17-epistanozolol-1'N-glucuronide and 17-epistanozolol-2'N-glucuronide in stanozolol-positive human urine samples due to the access to high-quality reference standards. Examination of excretion study samples shows large detection windows for the phase-II metabolites stanozolol-1'N-glucuronide and 17-epistanozolol-1'N-glucuronide up to 12 days and respectively up to almost 28 days. In addition, we present appropriate validation parameters for the analysis of these metabolites using a fully automatic method online solid-phase extraction (SPE) method already published before. Limits of identification (LOIs) as low as 100 pg/ml and other validation parameters like accuracy, precision, sensitivity, robustness, and linearity are given.

Comprehensive plasma-screening for known and unknown substances in doping controls.

Occasionally, doping analysis has been recognized as a competitive challenge between cheating sportsmen and the analytical capabilities of testing laboratories. Both have made immense progress during the last decades, but obviously the athletes have the questionable benefit of frequently being able to switch to new, unknown and untested compounds to enhance their performance. Thus, as analytical counteraction and for effective drug testing, a complementary approach to classical targeted methods is required in order to implement a comprehensive screening procedure for known and unknown xenobiotics. The present study provides a new analytical strategy to circumvent the targeted character of classical doping controls without losing the required sensitivity and specificity. Using 50 microL of plasma only, the method potentially identifies illicit drugs in low ng/mL concentrations. Plasma provides the biological fluid with the circulating, unmodified xenobiotics; thus the identification of unknown compounds is facilitated. After a simple protein precipitation, liquid chromatographic separation and subsequent detection by means of high resolution/high accuracy orbitrap mass spectrometry, the procedure enables the determination of numerous compounds from different classes prohibited by the World Anti-Doping Agency (WADA). A new hyphenated mass spectrometry technology was employed without precursor ion selection for higher collision energy dissociation (HCD) fragmentation experiments. Thus the mass spectra contained all the desired information to identify unknown substances retrospectively. The method was validated for 32 selected model compounds for qualitative purposes considering the parameters specificity, selectivity, limit of detection (<0.1-10 ng/mL), precision (9-28%), robustness, linearity, ion suppression and recovery (80-112%). In addition to the identification of unknown compounds, the plasma samples were simultaneously screened for known prohibited targets.

Quantification of urinary AICAR concentrations as a matter of doping controls.

Influencing the endurance in elite sports is one of the key points in modern sports science. Recently, a new class of prohibited substances reached in the focus of doping control laboratories and their misuse was classified as gene doping. The adenosine monophosphate activated protein kinase activator 5-amino-4-imidazolecarboxyamide ribonucleoside (AICAR) was found to significantly enhance the endurance even in sedentary mice after treatment. Due to endogenous production of AICAR in healthy humans, considerable amounts were present in the circulation and, thus, were excreted into urine. Considering these facts, the present study was initiated to fix reference values of renally cleared AICAR in elite athletes. Therefore a quantitative analytical method by means of isotope-dilution liquid chromatography (analytical column: C6-phenyl) coupled to tandem mass spectrometry, after a sample preparation consisting of a gentle dilution of native urine, was developed. Doping control samples of 499 athletes were analysed, and AICAR concentrations in urine were determined. The mean AICAR value for all samples was 2,186 ng/mL with a standard deviation of 1,655 ng/mL. Concentrations were found to differ depending on gender, type of sport and type of sample collection (in competition/out of competition). The method was fully validated for quantitative purposes considering the parameters linearity, inter- (12%, 7% and 10%) and intraday precision (14%, 9% and 12%) at low, mid and high concentration, robustness, accuracy (approx. 100%), limit of quantification (100 ng/mL), stability and ion suppression effects, employing an in-house synthesised (13)C(5)-labelled AICAR as internal standard.

Implementation of the HIF activator IOX-2 in routine doping controls - Pilot study data.

Early in 2020, racehorse doping cases revolved around the hypoxia-inducible factor (HIF) activator IOX-2. While the composition of IOX-2 has also been known and monitored in human doping controls for several years, the testing capability of routine sports drug testing methods was revisited for this newly surfaced doping agent. IOX-2 and the analytically well-established HIF activator roxadustat (FG-4592) share identical precursor/product ion pairs, enabling their co-detection in existing initial testing procedures in routine doping controls for the intact unconjugated analytes. In addition, hydroxylated IOX-2 and the corresponding glucuronic acid conjugates were identified as major metabolites in a microdose elimination study, contributing to enhanced initial testing and confirmation procedures.

Paper spray mass spectrometry - A potential complementary technique for the detection of polar compounds in sports drug testing.

In this proof-of-concept study, paper spray mass spectrometry was investigated as a high-throughput and fully automated technique for the initial testing of particularly polar compounds that are prohibited in sports. The technique allows the ionization of analytes from complex sample matrices such as blood and urine when spotted onto a paper strip. By minimizing sample preparation and omitting chromatographic separation, paper spray mass spectrometry benefits from considerable cost- and time-savings compared with conventional high performance liquid chromatography/tandem mass spectrometry, especially in cases where conventional reversed-phase liquid chromatography offers limited applicability. All but one of the investigated model compounds fulfilled the World Anti-Doping Agency's (WADA's) requirements regarding the applicable minimum required performance limits for initial testing procedures. In addition, the combination of paper spray mass spectrometry and ion mobility separation results in enhanced selectivity and sensitivity and is a particularly valuable analytical configuration.

Elimination profiles of microdosed ostarine mimicking contaminated products ingestion.

The possibility of nutritional supplement contamination with minute amounts of the selective androgen receptor modulator (SARM) ostarine has become a major concern for athletes and result managing authorities. In case of an adverse analytical finding (AAF), affected athletes need to provide conclusive information, demonstrating that the test result originates from a contamination scenario rather than doping. The aim of this research project was to study the elimination profiles of microdosed ostarine and characterize the time-dependent urinary excretion of the drug and selected metabolites. Single- and multi-dose administration studies with 1, 10, and 50 µg of ostarine were conducted, and collected urine samples were analyzed by LC-MS/MS following solid-phase extraction or enzymatic hydrolysis combined with liquid-liquid extraction. In the post-administration samples, both the maximum urine concentrations/abundance ratios and detection times of ostarine and its phase-I and phase-II metabolites were found to correlate with the administered drug dose. With regard to the observed maximum levels of ostarine, the time points of peak urinary concentrations/abundance ratios, and detection windows, a high inter-individual variation was observed. However, the study demonstrated that a single oral dose of as little as 1 µg can be detected for up to 9 (5) days by monitoring ostarine (glucuronide), and hydroxylated metabolites (especially M1a) appear to offer a considerably shorter detection window. The obtained data on ostarine (metabolite) detection times and urinary concentrations following different administration schemes support the interpretation of AAFs, in particular when scenarios of proven supplement contamination are discussed and supplement administration protocols exist.

Doping control analysis of trenbolone and related compounds using liquid chromatography-tandem mass spectrometry.

Trenbolone (17beta-hydroxy-estra-4,9,11-trien-3-one) and its derivatives such as 17alpha-methyltrenbolone represent a class of highly potent anabolic-androgenic steroids, which are prohibited in sports according to the regulation of the World Anti-Doping Agency (WADA). Due to marginal gas chromatographic properties of these compounds but excellent proton affinities resulting from a large and conjugated pi-electron system, liquid chromatography-tandem mass spectrometry (LC-MS/MS) has been the method of choice for the detection of these analytes in sports drug testing. Recent findings of trenbolone and methyltrenbolone in doping control urine samples of elite athletes demonstrated the importance of a sensitive and robust analytical method, which was based on an enzymatic hydrolysis of target compounds, liquid-liquid extraction and subsequent LC-MS/MS measurement. Diagnostic product ions obtained after collision-induced dissociation of protonated molecules were found at m/z 227, 211, 199 and 198, which enabled targeted screening using multiple reaction monitoring. Using 7 model compounds (trenbolone, epitrenbolone, methyltrenbolone, ethyltrenbolone, propyltrenbolone, 17-ketotrenbolone and altrenogest), the established method was validated for specificity, lower limits of detection (0.3-3ng/mL), recovery (72-105%), intraday and interday precision (< or =20%).

Pilot study on the effects of intravesical oxybutynin hydrochloride instillations on the validity of doping control urine samples.

According to class M2.1 of the World Anti-Doping Agency (WADA) Prohibited List, the manipulation of doping control urine samples to alter their integrity and validity is prohibited both in- and out-of-competition. However, some paraplegic athletes with an overactive bladder need to be regularly treated with anti-cholinergic and anti-spasmodic drugs such as oxybutynin, which are often administered intravesically to reduce the substantial side effects observed after oral application. So far, it remains unclear whether such bladder instillations have a negative impact on analytical procedures and thus represent an anti-doping rule violation. Within this pilot study, urine samples were collected from five paraplegic athletes before and after an intravesical oxybutynin hydrochloride instillation. The samples were routinely tested for the presence of performance-enhancing drugs and afterwards fortified with 25 model compounds representing different classes of doping agents (anabolic agents, cannabinoids, diuretics, glucocorticoids, hormone and metabolic modulators, and stimulants) at low and medium concentrations. Additionally, the pH value and specific gravity were measured and the presence of oxybutynin was qualitatively determined by gas chromatography-mass spectrometry (GC-MS). In initial testing procedures, all samples were tested negative. Oxybutynin was present in most of the samples but found to have no significant effect on the detectability of the 25 model compounds subsequently added to each urine specimen. Therefore, it can be concluded that intravesical instillations with oxybutynin hydrochloride do not alter the integrity and validity of doping control urine samples.