Drug Testing and Analysis最新文献

{"title":"Determining the Compliance of the Sysmex XR-1000 Haematology Analyser With WADA Athlete Biological Passport Specifications.","authors":"S C Voss, D Schwenke, J Hempel, P Mirtschink, A Wevelsiep, L Gaborini, N Robinson","doi":"10.1002/dta.3926","DOIUrl":"https://doi.org/10.1002/dta.3926","url":null,"abstract":"<p><p>The athlete biological passport (ABP) has been established as an anti-doping tool based on the statistical analyses of an athlete's biological variables over a period of time. It was introduced in 2007. An important aspect to ensure interlaboratory comparability was to use only one analytical platform-the Sysmex XT-2000. When the new Sysmex XN-1000 platform replaced the XT-2000i in 2019, there was a bias for the reticulocyte percentage. Although clinically insignificant, it interfered with interpreting athletes' haematological profiles for anti-doping purposes; therefore, it was necessary to adjust the haematological module. With the introduction of the new Sysmex XR-Series in 2023, an implementation of this new instrument could become necessary in the future. While the analytical performance of the XR-Series for clinical purposes has been evaluated previously, data in the context of ABP requirements, which are defined in WADA's technical documents, are not available. Therefore, our goals were to compare the XR-series with the XN-1000 and to evaluate their performance within an anti-doping context. Over 300 samples were analysed on the two instruments following WADA's technical document TD2021BAR, which defines the analytical requirements. The results for all ABP parameters including the calculated OFF-Score (OFF-hr) and the Abnormal Blood Profile Score (APBS) showed excellent interplatform comparability. In conclusion, our study demonstrates that the Sysmex XR meets WADA's requirements for haematological analysis. It can confidently replace the Sysmex XN in anti-doping laboratories without compromising the integrity of WADA's ABP longitudinal profiles.</p>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144590024","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Structural Characterization of Nitazene Analogs Using Electrospray Ionization-Tandem Mass Spectrometry (ESI-MS/MS).","authors":"Emma K Hardwick, J Tyler Davidson","doi":"10.1002/dta.3921","DOIUrl":"https://doi.org/10.1002/dta.3921","url":null,"abstract":"<p><p>Nitazene analogs are potent novel synthetic opioids (NSOs) that are becoming increasingly common and pose a threat to the public because of their fentanyl-like effects. Although 12 nitazene analogs are currently classified as Schedule I under the U.S. Controlled Substances Act, novel analogs continue to emerge, making their identification in forensic laboratories exceedingly difficult. Liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) is commonly utilized in toxicology laboratories and is becoming more common for seized drug analysis, particularly for compounds less suited for gas chromatography-electron ionization-mass spectrometry (GC-EI-MS). This study provides a comprehensive structural characterization of 38 representative nitazene analogs using LC-ESI-MS/MS instrumentation, including the proposed fragmentation mechanisms that lead to the formation of diagnostic product ions, enabling analog differentiation. General fragmentation pathways and mechanisms are proposed for all nitazene analogs, including inductive cleavages and molecular rearrangements. Overall, the most common product ions for nitazene analogs are derived from the substitutions to the amine or benzyl moieties, such as m/z 100, m/z 72, m/z 44, and m/z 107. However, the presence of different substitutions shifts the observed product ions. For example, recently occurring piperidine or pyrrolidine rings produce diagnostic product ions at m/z 112 and m/z 98, respectively. Therefore, modification to the core nitazene structure produces different diagnostic product ions, which can be used to identify existing and novel analogs. This study provides a comprehensive assessment of the fragmentation behavior of nitazene analogs under ESI-MS/MS conditions, which provides the basis for identifying new structural modifications in novel nitazene analogs.</p>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144558552","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Self-Reported Use of Thyroid Hormones by Athletes at the Olympic Games.","authors":"Mark Stuart, Damien Rhumorbarbe, Audrey Kinahan, Matti L Gild, Roderick Clifton-Bligh, David Handelsman","doi":"10.1002/dta.3923","DOIUrl":"https://doi.org/10.1002/dta.3923","url":null,"abstract":"<p><p>Thyroid hormones (TH) are widely used for treatment of hypothyroidism or thyroid cancer in medical practice, but their use among elite athletes without thyroid disease remains controversial. Despite lacking clear ergogenic benefits, some athletes reportedly use thyroxine (T4) and/or triiodothyronine (T3) with the belief that they enhance performance or facilitate weight management. This study investigates self-reported TH use by athletes at the Tokyo 2020, Beijing 2022, and Paris 2024 Olympic Games, analyzing trends based on sex, age, country, and sport. Across these three events, 1.7% of tested athletes reported TH use, with reported use higher among females and in explosive power sports, which is higher than expected for the youthful Olympic participants studied. However, TH use has declined to 1.3% at Paris 2024 compared to the previous Games (Tokyo 2020: 1.8%; Beijing 2022: 2.7%). Whether this decline is due to a growing awareness of the potential harms and/or lack of performance benefits could not be determined by this study.</p>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144551519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metabolic Studies of Nandrolone Decanoate in Castrated Horses After Intramuscular Administration.","authors":"Yat-Ming So, Wai Him Kwok, Christina W Y Tang, Celia O L Wong, Terence S M Wan, Emmie N M Ho","doi":"10.1002/dta.3919","DOIUrl":"https://doi.org/10.1002/dta.3919","url":null,"abstract":"<p><p>This paper describes the studies of the in vitro biotransformation of nandrolone decanoate and its metabolic fate in equine plasma and urine after intramuscular administration to castrated thoroughbred horses. The in vitro metabolic study was performed using homogenised horse liver, and the more prominent in vitro biotransformation pathways were found to include hydrolysis, reduction, oxidation and sulfation, mainly resulting in seven Phase I metabolites and one Phase II metabolite. The administration study of nandrolone decanoate was carried out using three retired thoroughbred geldings, each of which was administered intramuscularly with 800 mg of nandrolone decanoate (Deca-Durabolin) once weekly for three consecutive weeks. Nandrolone decanoate and the majority of the identified in vitro metabolites were detectable in post-administration plasma samples for at least 20 days (last sample collected) after the last administration. Although nandrolone decanoate was not found in any post-administration urine, nandrolone (as a metabolite) and its downstream metabolites can be detected for at least 20 days post-administration (last sample collected). For doping control purpose, nandrolone decanoate itself could be a suitable target analyte in horse plasma for effectively controlling its misuse in equine sports.</p>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":" ","pages":""},"PeriodicalIF":2.6,"publicationDate":"2025-07-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144525713","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Toward a Cannabis Terroir: Untargeted Metabolomic Profiling of Authentic Samples Using Gas Chromatography–High-Resolution Mass Spectrometry (GC-HRMS) and Liquid Chromatography–High-Resolution Tandem Mass Spectrometry (LC-HRMS/MS)","authors":"Sandra N. Poetzsch,&nbsp;Michael Poetzsch,&nbsp;Thomas Kraemer,&nbsp;Andrea E. Steuer","doi":"10.1002/dta.3922","DOIUrl":"10.1002/dta.3922","url":null,"abstract":"<p><i>Cannabis sativa L</i>. constituents, such as cannabinoids, terpenes, flavonoids, and other secondary metabolites, determine the plant's (medicinal) effects and properties in a complex interplay, a phenomenon known as the entourage effect. However, environmental influences like cultivation method, soil, light, and climate might also influence the plant's chemical composition—and thus its therapeutic profile. Much like in viticulture, the concept of a “cannabis terroir” might play an important role in determining the plant's chemical phenotype. The aim of this study was therefore to make these complex properties analytically accessible and develop a comprehensive metabolomics workflow using gas chromatography–high-resolution mass spectrometry (GC-HRMS) and liquid chromatography–high-resolution tandem mass spectrometry (LC-HRMS/MS) in positive and negative ionization mode, applying HILIC and reversed phase chromatography to assess multiple chemical classes. Data processing and statistical analysis were done in MS-DIAL and MetaboAnalyst, respectively. The method was applied to 35 CBD-type cannabis flowers grown under different environmental conditions, and compounds belonging to various chemical classes were successfully detected. Principal component analysis revealed distinct clustering of the samples, and key discriminative features were identified, including cannabinoids, terpenes such as β-caryophyllene and α-humulene, cuticular alkanes (e.g., pentacosane and nonacosane), and polar compounds such as choline and trigonelline. The markers enabled a discrimination of samples not only by chemical phenotype but also by cultivation environment, supporting the emerging concept of a cannabis terroir. In conclusion, this study introduces an analytical framework for the comprehensive chemical profiling of cannabis employing GC-HRMS and LC-HRMS analysis and advanced statistical techniques.</p>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":"17 10","pages":"2086-2095"},"PeriodicalIF":2.7,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://analyticalsciencejournals.onlinelibrary.wiley.com/doi/epdf/10.1002/dta.3922","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144525714","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"SARMs, Metabolic Modulators and Growth Hormone Secretagogues in Suspected Illegal Medicines, Bought as Sport Performance Enhancers: A Retro- and Prospective Study Within the GEON","authors":"M. Mendoza Barrios,&nbsp;E. Deconinck,&nbsp;C. Vanhee,&nbsp;E. K. Lamme,&nbsp;I. ‘t Hart-Bakker,&nbsp;P. V. Syversen,&nbsp;O. Bøyum,&nbsp;G. Li-Ship,&nbsp;S. Young,&nbsp;A. Blazewicz,&nbsp;M. Poplawska,&nbsp;B. Hakkarainen,&nbsp;N. Hang Huynh,&nbsp;A. Hackl,&nbsp;M. J. Portela,&nbsp;P. Martinho,&nbsp;N. Beerbaum,&nbsp;M. C. Gaudiano,&nbsp;M. Raimondo,&nbsp;V. Marleau,&nbsp;J. Cloutier,&nbsp;J. Ollerenshaw,&nbsp;A. Hansen,&nbsp;J. Mills,&nbsp;M. Aha,&nbsp;C. Luchte,&nbsp;M. Miquel","doi":"10.1002/dta.3918","DOIUrl":"10.1002/dta.3918","url":null,"abstract":"<div>\u0000 \u0000 <p>Although the abuse of muscle-building compounds in elite sports is already known for a long time, these products have become more popular in recreational sport over the past years. Although anabolic steroids are still the most popular ones in this context, the use of other molecules with anabolic properties is on the rise. Three categories of such products are the selective androgen receptor modulators (SARMs), the metabolic modulators and the growth hormone secretagogues (GHS). Based on this trend and the outcomes of a previous market surveillance study in the domain of illegal products (MSSIP), the Falsified Medicines Working Group of the General European Official Medicines Control Laboratories (OMCL) Network (GEON) decided to conduct an MSSIP with focus on SARMs, metabolic modulators and GHS over a period of 5 years. In total 324 samples and 354 results, reported by 14 laboratories in 13 countries, members of the GEON, were taken into account, for which the majority of the samples originated from illegal distribution. Sixty-five percent of the seized products were represented as medicine, though 24% as dietary supplements, which is of concern because here the (recreational) sporter is not aware he is taking an (unapproved) pharmaceutical. Eighteen different molecules, within the scope of the study, were reported with as top 5: ibutamoren, ligandrol, ostarine, cardarine and andarine. From the limited quantitative data reported, it can be assumed that the majority of the samples contain active doses and some are even overdosed, so health risks for the consumers cannot be neglected.</p>\u0000 </div>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":"17 10","pages":"2078-2085"},"PeriodicalIF":2.7,"publicationDate":"2025-06-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144473530","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Monitoring Community Use of Benzodiazepines Through Wastewater-Based Epidemiology","authors":"Maarten Quireyns,&nbsp;Tim Boogaerts,&nbsp;Natan Van Wichelen,&nbsp;Diāna Vanaga-Arāja,&nbsp;Olesia Rudminienė,&nbsp;Ruxanda Iliescu,&nbsp;Milica Georgescu,&nbsp;Sofie Schaerlaekens,&nbsp;Naomi De Roeck,&nbsp;Peter Delputte,&nbsp;Adrian Covaci,&nbsp;Alexander L. N. van Nuijs","doi":"10.1002/dta.3915","DOIUrl":"10.1002/dta.3915","url":null,"abstract":"<div>\u0000 \u0000 <p>Benzodiazepines and related z-drugs (BZDs) are widely used pharmaceuticals but require careful monitoring due to limited efficacy, tolerance development and the risk of dependence. Wastewater-based epidemiology (WBE) is a valuable approach to gather population-wide information on consumption patterns through analysis of influent wastewater. This study examines how overlapping metabolic pathways within the BZD drug class can lead to misinterpretation if not carefully considered. An analytical method is developed and validated for 26 biomarkers of prescription BZDs in influent wastewater using solid-phase extraction and liquid chromatography–tandem mass spectrometry and applied to influent wastewater samples for the first time in Belgium (13 locations), Latvia (1), Lithuania (3) and Romania (1). The countries were chosen for their differing prescription BZD market registration, allowing testing of different hypotheses. To aid in complex data interpretation, this study presents a structured categorisation of BZDs into <i>direct</i> biomarkers, which directly reflect consumption, and <i>downstream</i> biomarkers, which are influenced by multiple BZDs, and further discusses the implication this has on the interpretation. Spatial differences were noted among <i>direct</i> biomarkers such as higher consumption of zolpidem in Belgium and zopiclone in Riga (LVA). Downstream biomarkers had higher population-normalised mass loads but cannot be interpreted in isolation, for example, lorazepam (ranging 4–25 mg/day/1000 inhabitants over all locations), lormetazepam (8–30), oxazepam (10–50) and temazepam (1–12). These findings highlight challenges in interpreting BZD consumption trends and emphasise the need of distinguishing different biomarker classes to ensure accurate and comparable results across studies needed to guide informed decision-making.</p>\u0000 </div>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":"17 10","pages":"2066-2077"},"PeriodicalIF":2.7,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144324004","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Development of an Optimized Extraction Method to Recover Drug Material From Used Test Strips for Comprehensive Drug Checking","authors":"Meghan G. Appley,&nbsp;Elise M. Pyfrom,&nbsp;Rae A. Elkasabany,&nbsp;Rick Rousch,&nbsp;Edward Sisco","doi":"10.1002/dta.3911","DOIUrl":"10.1002/dta.3911","url":null,"abstract":"<div>\u0000 \u0000 <p>Drug-checking programs use point-of-need testing (e.g., test strips) and laboratory-based analysis to rapidly identify emerging drug threats, but each has limitations. Test strips are quick but compound or class specific, whereas laboratory testing can identify more compounds but have lengthy turnaround times. To address these limitations, it was proposed that compounds could be extracted from used test strips for additional analyses allowing for rapid on-site information followed by comprehensive laboratory results. The method development process involved four parts: determining the optimal extraction approach, assessing the feasibility of performing direct analysis in real-time mass spectrometry (DART-MS) analysis on extracts, determining the limits of detection (LODs) for a range of analytes, and evaluating the method using used test strips submitted by harm reduction sites. The optimized method consisted of extracting analytes of interest from a cut test strip using 0.5-mL methanol while vortexing for 10 s. DART-MS successfully identified the compounds of interests, and the test strip chemical background was identified. LODs were found to be as low as a mass fraction of 0.005 in a mixture. For the samples submitted by harm reduction sites, concordance between extracts and test strip results was 96%, and the agreement in compound identification between used test strip extracts and authentic drug collection samples was approximately 80% regardless of test strip type and preparation. This work shows that additional analyses of extracted test strips can provide a low-barrier way for high-quality testing that can be used to increase data on the drug landscape.</p>\u0000 </div>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":"17 10","pages":"2054-2065"},"PeriodicalIF":2.7,"publicationDate":"2025-06-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144324003","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Analysis of Methyltestosterone and Testosterone Propionate in Dried Blood Spots After Transdermal Application","authors":"Asami Miyamoto,&nbsp;Masato Okano,&nbsp;Masanori Ota,&nbsp;Mitsuhiko Sato","doi":"10.1002/dta.3914","DOIUrl":"10.1002/dta.3914","url":null,"abstract":"<div>\u0000 \u0000 <p>In the past few years, doping tests have been performed with dried blood spots (DBS) as test samples; this sampling method is minimally invasive and requires minimal storage space. Steroid esters are stable in dried blood, allowing the direct analysis of testosterone esters. In Japan, the cream-based formulation containing 17α-methyltestosterone (MeT) and testosterone propionate (TP) is available as an over-the-counter drug for hair growth. Here, we investigated whether the transdermal uptake of this formulation could be detected using the existing method for steroid ester analysis in DBS. A method that was previously validated to detect and identify TP could also detect MeT. We developed a high throughput liquid chromatography–tandem mass spectrometry method to identify MeT in DBS. The limits of detection and identification of MeT were 0.1 ng/mL and 0.6 ng/mL, respectively. Five male human subjects received the cream-based formulation of MeT and TP transdermally. We then collected blood samples by finger pricking and made DBS on cellulose paper. Using this method, MeT was detected and identified up to 97 h after the final application. TP was also detected up to 97 h and identified up to 49 h after the final application. The developed method provides a direct confirmation of the presence of the drug. Moreover, using cream preparations could lead to contamination from MeT and TP remaining on the fingertip skin during fingertip puncture sampling.</p>\u0000 </div>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":"17 10","pages":"2045-2053"},"PeriodicalIF":2.7,"publicationDate":"2025-06-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144232782","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Detection of Transdermal Application of Testosterone to Racehorses by Analysis of Urine and Plasma","authors":"Marjaana Viljanto,&nbsp;Charlotte Cutler,&nbsp;Jocelyn Habershon-Butcher,&nbsp;Pamela Hincks,&nbsp;James Scarth","doi":"10.1002/dta.3905","DOIUrl":"10.1002/dta.3905","url":null,"abstract":"<div>\u0000 \u0000 <p>The use of testosterone in racehorses is predominantly monitored using international urine and plasma concentration-based thresholds and complementary steroid ratios. To date, there has been no published pharmacokinetic study on transdermally applied testosterone products in horses and whether their use could result in adverse analytical findings. Therefore, quantitative analysis of testosterone and epitestosterone in urine and testosterone in plasma samples was performed following a pilot multi-dose transdermal Testogel administration (1 mg/kg once a day for 7 days on clipped skin) to one gelding and one mare. The peak concentrations (C_max) of free testosterone were 1060 and 1800 pg/mL in gelding and mare plasma, respectively. Testosterone concentrations exceeded the international plasma threshold of 100 pg/mL consistently for up to 4 h post-administration, after which detection above the threshold was sporadic up to 127 h. In urine, C_max of free and conjugated (sulfate and glucuronide) testosterone were 700 and 323 ng/mL in gelding and mare urine, respectively. In the gelding, testosterone concentrations exceeded the international urine threshold of 20 ng/mL consistently for up to 47 h post-administration, but sporadically up to 143 h. In all samples, testosterone: epitestosterone ratios were greater than 5, another requirement for adverse analytical findings in geldings. In the mare, testosterone concentrations exceeded the urine threshold of 55 ng/mL consistently for up to 71 h post-administration, but sporadically up to 167 h. Therefore, these limited results for one gelding and one mare demonstrate that doping control following transdermal applications of testosterone to racehorses is possible using existing approaches.</p>\u0000 </div>","PeriodicalId":160,"journal":{"name":"Drug Testing and Analysis","volume":"17 10","pages":"2036-2044"},"PeriodicalIF":2.7,"publicationDate":"2025-06-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144214492","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}