Drug Testing and Analysis最新文献

Beta₂-adrenergic agonists are widely used for bronchial relief in respiratory conditions such as asthma and exercise-induced bronchoconstriction. However, this drug class has also been shown to have muscle anabolic properties. Kelch-Like Family Member 41 (KLHL41) is a sarcomeric protein implicated in muscle remodeling and hypertrophy. In this study, we examined the effects of oral clenbuterol, therapeutic inhaled formoterol, and resistance training on KLHL41 protein abundance in human skeletal muscle. KLHL41 levels were measured by immunoblotting in vastus lateralis muscle biopsies from healthy adults following 2 weeks of oral clenbuterol administration, 6 weeks of inhaled formoterol at therapeutic doses, or 8 weeks of resistance training. We also assessed sex differences and the effects of acute versus prolonged interventions. Prolonged oral clenbuterol administration significantly increased KLHL41 abundance compared to placebo (p < 0.001), with a magnitude similar to that observed after resistance training (p < 0.01), whereas therapeutic inhaled formoterol had no effect on KLHL41 levels. Neither acute clenbuterol administration nor a single resistance training session altered KLHL41 abundance, and no sex differences were observed in baseline KLHL41 levels. These findings indicate that beta₂-adrenergic stimulation via oral clenbuterol, but not therapeutic inhalation of formoterol, promotes sarcomeric remodeling through KLHL41-related pathways similar to those activated by resistance training. The distinct effects of these agents on KLHL41 support current anti-doping regulations prohibiting clenbuterol use and highlight KLHL41 as a potential molecular marker of skeletal muscle adaptation to hypertrophic stimuli.

This study presents a novel physio-pharmacological framework for assessing the potential performance-enhancing effects of substances and methods included in the 2022 World Anti-Doping Agency (WADA) Prohibited List across 160 Olympic sport disciplines. An expert panel evaluated 31 consolidated pharmacological categories for their capacity to enhance performance across six core physiological athletic demands. Using a calibrated scoring function and bilinear interpolation, we mapped these effects to each sport's dominant physiological profile. Findings confirmed the well-known ergogenic effects of anabolic agents and erythropoietins for power and endurance-based sports, respectively, including the general ergolytic effects of narcotics and cannabinoids. Moreover, the methodology can be used to evaluate any new sport or substance given their respective physiological demands. The study underscores the need for targeted anti-doping strategies, suggesting that risk assessment and test distribution planning should be aligned with sport-specific physiological demands and the relative performance advantages conferred by different doping strategies. This summary of the current physiological knowledge and pharmacological knowledge has the potential to enhance detection efficiency, optimize resource allocation, and refine prohibited substance screening in elite sport.

Unintentional doping violations have been reported after secondary skin exposure, including partner contact or contact sports. Methyltestosterone (MT), an anabolic androgenic steroid on the World Anti-Doping Agency Prohibited List, is readily available in Japan as an over-the-counter topical hair-growth preparation and as oral tablets. This study evaluated whether transdermal absorption of MT can be distinguished from oral administration using human urine and dried blood spot (DBS) analyses. Ten men received MT once daily for five consecutive days (five oral, five transdermal). The urinary tetrahydro-metabolites 17α-methyl-5α-androstane-3α,17β-diol (5α-THMT) and 17α-methyl-5β-androstane-3α,17β-diol (5β-THMT) were detectable within hours after administration for both routes. Following transdermal administration, 5α-THMT remained detectable up to 97 h after the final administration, whereas, after oral administration, 5β-THMT persisted longer, up to 265 h. Transdermal application produced a marked increase in 5α-THMT, consistent with high 5α-reductase activity in skin, yielding a significantly higher 5α-THMT/5β-THMT ratio than after oral administration. Nonetheless, individuals with inherently high 5α-reductase activity may exhibit elevated ratios even after oral dosing, warranting careful interpretation. In DBS after oral dosing, parent MT was generally detectable up to 24 h, providing a shorter detection window than urinary tetrahydro-metabolites. Overall, combining urine (tetrahydro-metabolites) and DBS (parent MT) analyses enables effective detection of MT use and supports differentiation of administration routes.

The serum testosterone-to-luteinizing hormone (T/LH) ratio has previously been suggested as a sensitive marker of testosterone use in an anti-doping setting. When measured with an automated immunoassay platform, this ratio represents a quick and cost-effective screening biomarker to further direct isotope ratio mass spectrometry (IRMS) testing efforts in concurrently collected urine samples to confirm testosterone abuse. To evaluate the practicality of implementing the serum T/LH ratio for routine use, testosterone values in 356 serum samples were compared between a “gold-standard” LC–MS/MS method and an automated immunoassay method. Excellent correlation and minimal bias between the two methods were observed, highlighting the validity of the immunoassay method. Next, a testosterone administration study utilizing a transdermal delivery route was conducted to compare the effectiveness of the serum T/LH ratio to the currently used serum testosterone to androstenedione (T/A4) and urinary testosterone to epitestosterone (T/E) ratios. The serum T/LH ratio was more sensitive than the T/A4 ratio and showed similar sensitivity to the urinary T/E ratio with high interindividual variability. Finally, T/LH analysis was conducted on 626 capillary serum samples collected in the field from male Ultimate Fighting Championship athletes. Of the three samples that showed elevated T/LH ratios in this pool, two of the corresponding urine samples were IRMS positive, one of which showed an unremarkable urinary T/E ratio and relatively normal steroid profile. These results indicate serum T/LH ratio monitoring provides a beneficial addition to the anti-doping tool kit and can improve urinary IRMS testing recommendations.

Voxelotor, a therapeutic drug for sickle cell disease, has been reported to elevate serum erythropoietin and hemoglobin levels in healthy individuals. Because of its potential to alter blood parameters, the World Anti-Doping Agency (WADA) classified voxelotor under category M1 of the 2023 Prohibited List. Despite this classification, little is known about its metabolic behavior in either humans or animals. In this study, the metabolism of voxelotor was investigated in Thoroughbred horses after oral administration. Using liquid chromatography high-resolution mass spectrometry (LC-HRMS), 35 metabolites were detected. Among them, the most prominent pathways included hydroxylation and reductive transformations (Phase I), as well as glucuronidation and sulfonation (Phase II). Notably, several glucuronide conjugates and hydroxylated derivatives were identified as major metabolites, with extended detection times that make them particularly relevant for antidoping surveillance. Blood analyses also revealed changes in red blood cell count, hemoglobin concentration, packed cell volume, and platelet levels. Together, these findings provide practical insight into voxelotor's metabolic profile in equines and highlight specific metabolites useful for doping control. Further studies are needed to better define its hematological impact and to confirm whether the observed clinical effects are drug related.