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Rationale: To uphold the integrity of horseracing and equestrian sports, it is critical for an equine doping control laboratory to develop a comprehensive screening method to cover a wide range of target substances at the required detection levels in equine urine. Methods: The procedure involved the enzymatic hydrolysis of 3 mL urine samples followed by solid‐phase extraction using HF Bond Elut C18 cartridge. The resulting extracts were then separated on a C18 reversed‐phase column and analyzed using liquid chromatography/high‐resolution mass spectrometry (LC/HRMS) in both electrospray ionization positive and negative modes in two separate injections. The analytical data were obtained in full scan and product ion scan (PIS) modes in an 11 min LC run. Results: The method can detect 1011 compounds (in both positive and negative ion modes). Over 95% of the target compounds have limits of detections (LODs) ≤10 ng/mL, and more than 50% of the LODs are ≤0.5 ng/mL. The lowest LOD can reach down to 0.01 ng/mL. The applicability of the method was demonstrated by the successful detection of prohibited substances in overseas and domestic equine urine samples. Conclusions: We have successfully developed a regular screening method for equine urine samples that can detect more than 1000 compounds at sub‐ppb levels in both positive and negative ion modes with full scan and PIS using LC/HRMS. Furthermore, this method can theoretically be expanded to accommodate an unlimited number of prohibited substances in full‐scan mode. [ABSTRACT FROM AUTHOR]

Rationale: Osilodrostat is an inhibitor of 11‐beta‐hydroxylase (CYP11B) and is used for the treatment of Cushing's disease but also categorized as an anabolic agent. The use of osilodrostat is prohibited in horseracing and equestrian sports. To the best of our knowledge, this is the first metabolic study of osilodrostat in equine plasma. Methods: Potential metabolites of osilodrostat were identified by differential analysis using data acquired from pre‐ and post‐administration plasma samples after protein precipitation with liquid chromatography electrospray ionization high‐resolution mass spectrometry (LC/ESI–HRMS). [Correction added on 27 January 2023, after first online publication: In the preceding sentence, "C–HRMS" was changed to "LC/ESI–HRMS" in this version.] For quantification of osilodrostat, a strong cation exchange solid‐phase extraction was employed, and the extracts were analyzed using LC/ESI–triple quadrupole tandem mass spectrometry (LC/ESI–QqQ‐MS/MS) to establish its elimination profile. Such extracts were further analyzed using LC/ESI–HRMS to investigate the detectability of osilodrostat and its identified mono‐hydroxylated metabolite over a 2‐week sampling period. Results: Mono‐hydroxylated osilodrostat was identified based on the differential analysis and mass spectrometric interpretations, and it was found to be the most abundant metabolite in plasma. Elimination profile of osilodrostat in plasma was successfully established over the 24‐h post‐administration period. Both osilodrostat and its mono‐hydroxylated metabolite were detected up to the last sampling point at 2 weeks using HRMS, and osilodrostat could be confirmed up to 8‐day post‐administration with its reference material using HRMS as well. Conclusions: For doping control, screening of both the parent drug osilodrostat and its mono‐hydroxylated metabolite in equine plasma would be recommended due to their extended detection windows of up to 2 weeks. Given the availability of reference material for potential confirmation in forensic samples, osilodrostat is considered the most appropriate monitoring target. [ABSTRACT FROM AUTHOR]

Indoor positioning system (IPS) technologies have widespread applications in logistics, intelligent manufacturing, healthcare monitoring, etc. The recently released Bluetooth low‐energy (BLE) 5.1 specification enables in‐phase and quadrature‐phase (I/Q) data measurements. It allows angle of arrival estimation and becomes a natural choice for IPS implementation. Conventional BLE 5.1 IPSs use multiple anchors to provide massive redundancy to improve system robustness. It however demands effective approaches to leverage redundancy. Besides, interference due to various environmental factors can introduce severe errors to I/Q data and affect positioning accuracy. Facing these challenges, herein, a novel deep learning‐based multianchor BLE 5.1 IPS is proposed. The system aggregates measurements from multiple anchors and makes them available at regular time steps. Then, a novel attentional filtering network tailored to infer high‐quality I/Q sample data is developed and a spatial regularization loss incorporating spatial location relationships to strengthen the feature embedding discrimination is proposed. Two multianchor BLE 5.1 I/Q sample datasets are developed and released for public download. Numerical experiments are carried out to compare the proposed method with previous BLE 5.1 IPS methods and methods utilizing other radio frequency data. Results indicate that the proposed method consistently achieves submeter accuracy and significantly outperforms the state‐of‐the‐art approaches. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the pharmacokinetics (PK) of tranexamic acid (TXA) in horses and estimate its irrelevant plasma and urine concentrations using the pharmacokinetic/pharmacodynamic (PK/PD) approach by applying the Pierre‐Louis Toutain model. TXA was intravenously administered to eight thoroughbred mares, and plasma and urine TXA concentrations were quantified by liquid chromatography/tandem mass spectrometry. The quantified data were used to calculate the PK parameters of TXA in horses. The plasma elimination curves were best‐fitted to a three‐compartment model. Using the Toutain model approach, irrelevant plasma and urine TXA concentrations were estimated to be 0.0206 and 0.997 μg/mL, respectively. The typical values of clearance, steady‐state volume of distribution, and steady‐state urine‐to‐plasma ratio were 0.080 L/kg/h, 0.86 L/kg, and 49.0, respectively. The obtained irrelevant concentrations will be useful for establishing relevant regulatory screening limits for effective control of TXA use in horse racing and equestrian sports. [ABSTRACT FROM AUTHOR]

Vadadustat is a newly launched hypoxia-inducible factor stabilizer with anti-anemia and erythropoietic effects; however, its use in horses is expressly forbidden in both racing and equestrian competitions. Following our previous report on the pharmacokinetic study of vadadustat in horse plasma and urine, a long-term longitudinal analysis of vadadustat in horse hair after nasoesophageal administration (3 g/day for 3 days) to three thoroughbred mares is described in this study. Our main objective is to further extend the detection period of vadadustat for the purpose of doping control. Three bunches of mane hair from each horse were collected at 0 (pre), 1, 2, 3 and 6 month(s) post-administration. These hair samples were each cut into 2-cm segments and pulverized after decontamination of hair samples. The analyte in the powdered hair samples was extracted with liquid–liquid extraction followed by further purification by solid-phase extraction with strong anion exchange columns. The amount of vadadustat incorporated into the hair was quantified with a newly developed and validated method using liquid chromatography–high-resolution mass spectrometry. Our results show that vadadustat was confirmed in all post-administration hair samples, but its metabolites were not present. Thus, the detection window for vadadustat could be successfully extended up to 6 months post-administration. Interestingly, the 2-cm segmental analysis revealed that the tip of the drug band in the hair shifted along with the hair shafts in correspondence with the average hair growth rate (∼2.5 cm/month) but gradually diffused more widely from 2 cm at 1 month post-administration to up to 14 cm at 6 months post-administration. However, the loss in the total amount of vadadustat in hair over time was observed to most likely be due to the degradation of vadadustat. These findings will be useful for the control of abuse and/or misuse of vadadustat and the interpretation of positive doping cases. [ABSTRACT FROM AUTHOR]

In the context of doping control, conventional direct chemical testing detects only a limited scope of target substances in equine biological samples. To expand the ability to detect doping agents and their detection windows, metabolomics has recently become a common approach for monitoring alteration of biomarkers caused by doping agents in relevant metabolic pathways. In horse racing, remarkable changes in metabolic profiles between the rest state and racing are likely to affect the identification of doping biomarkers. Previously, we reported a limited number of significantly upregulated metabolites after racing, based on a non‐targeted metabolomics approach using out‐of‐competition and post‐race equine plasma samples. In this study, we performed a more thorough analysis of the data set, using pathway analysis to establish a post‐race biomarkers database (PBD) that includes upregulated and downregulated metabolites, their fold changes, and relevant pathways, with the main objective of improving our understanding of changes in physiological status related to horse racing. Statistical analysis of the PBD revealed that two peak combinations of pentadecanoyl carnitine/galactosylglycerol (P/G) and heptadecanoyl carnitine/galactosylglycerol (H/G) could be used as potential biomarkers for the discrimination of the rest and post‐race groups. To demonstrate the applicability of the PBD, we validated the post‐race biomarkers P/G and H/G (highly involved in lipid metabolism) by a single‐blind test. This strategy, which combines establishment of a biomarker database with pathway analysis, represents a powerful tool for discovering potential doping biomarkers in the future. [ABSTRACT FROM AUTHOR]