Do dried blood spots have the potential to support result management processes in routine sports drug testing?-Part 2: Proactive sampling for follow-up investigations concerning atypical or adverse analytical findings

Do dried blood spots have the potential to support result management processes in routine sports drug testing?-Part 3: LC-MS/MS-based peptide analysis for dried blood spot sampling time point estimation

Along with the recent acknowledgement of the World Anti-Doping Agency to use dried blood spot (DBS) samples for routine doping control purposes, there have been propositions to use DBS as a matrix that allows regular proactive remotely supervised self-sampling, providing potential longitudinal monitoring of an athlete's exposure to doping agents. However, several organizational aspects have to be considered before implementation, such as the verification of the sample collections time point. Based on a previous untargeted proteomics workflow utilizing liquid chromatography-high-resolution mass spectrometry (LC-HRMS) to identify protein/peptide markers to define the time since deposition of a bloodstain, the aim of the current study was to develop a targeted LC-HRMS/MS analytical method for promising peptidic target analytes. A long-term DBS storage experiment was carried out over a 3-month period (sample collection time points: 0, 2, 4, 7, 14, 21, 28, 42, 56, 70, 84 and 91 days) with DBS samples of 10 volunteers for longitudinal investigation of signal abundance changes of targeted peptide sequences at different storage temperatures (room temperature [RT], 4°C and -20°C). Prior to experimental analysis, LC-HRMS/MS method characteristics were successfully assessed, including intraday precision, carryover and sample extract stability. For estimation of DBS sample collection time points, ratios of two peptides that originate from the same protein prior to tryptic digestion were created. Two targeted peptide area ratios were found to significantly increase after being stored at RT for 28 days, representing potential markers for future use in routine doping controls that contribute to advancing complementary avenues in anti-doping.

Comprehensive analysis of prohibited substances and methods in sports: Unveiling trends, pharmacokinetics, and WADA evolution

This review systematically compiles sports-related drugs, substances, and methodologies based on the most frequently detected findings from prohibited lists published annually by the World Anti-Doping Agency (WADA) between 2003 and 2021. Aligned with structure of the 2023 prohibited list, it covers all proscribed items and details the pharmacokinetics and pharmacodynamics of five representatives from each section. Notably, it explores significant metabolites and metabolic pathways associated with these substances. Adverse analytical findings are summarized in tables for clarity, and the prevalence is visually represented through charts. The review includes a concise historical overview of doping and WADA's role, examining modifications in the prohibited list for an understanding of evolving anti-doping measures.

Liquid vs dried blood matrices: Application to longitudinal monitoring of androstenedione, testosterone, and IGF-1 by LC-MS-based techniques

BACKGROUND

Dried blood spots have recently been approved by the World Anti-Doping Agency as an alternative biological matrix for testing of doping substances. However, their use is limited to the detection of non-threshold compounds without a Minimum Reporting Level due to the numerous issues related to quantitative analyses and the limitation on testing capabilities of a haemolysed matrix.

AIM

In this study androstenedione, testosterone and IGF-1 were longitudinally monitored in four different blood matrices to evaluate the potential of liquid capillary blood as an alternative matrix for quantitative determination in doping control analysis.

METHODOLOGY

The analytical protocols developed to pretreat 20 μL of the blood matrices selected were based: i) for testosterone and androstenedione, on supported liquid extraction for liquid blood matrices, and on ultrasonication in the presence of methanol for dried blood matrices; ii) for IGF-1, proteins precipitation followed by evaporation of the supernatant was used to pretreat both liquid and dried blood matrices. The detection for all the target analytes was performed using liquid chromatography coupled to mass spectrometry. The analytical workflows, once optimized, were fully validated according to the requirements of World Anti-Doping Agency and ISO 17025 standard and used for the analysis of venous (serum) and capillary (liquid plasma and dried whole blood collected using either volumetric or non-volumetric devices) blood samples collected from 7 healthy subjects.

RESULTS

The validation results showed satisfactory performance as related to specificity, sensitivity, matrix effects, linearity, accuracy, and precision in all the blood matrices evaluated despite the limited volume of sample used. The analysis of the different blood matrices collected from the subjects showed non-significant differences between the levels of testosterone and androstenedione measured in dried (fixed volume collected) and liquid matrices. An acceptable underestimation (lower than 15 %) was observed in capillary plasma compared to venous serum. The testosterone/androstenedione ratio was similar in all the blood matrices considered (bias lower than 5 %), indicating this parameter was not affected by either the blood matrix or collection device selected. For IGF-1, the levels measured in liquid blood matrices differed significantly (bias higher than 20 %) from those measured in dried whole blood matrices, suggesting haemolyzed blood might represent a challenge for the determination of macromolecules, mainly due to the complexity of the whole blood matrix in comparison to plasma/serum.

NOVELTY

The outcomes of our study suggest that liquid capillary blood might open new avenues to blood microsampling in doping control field. It represents an efficient alternative to overcome the issues related to venous blood and dried blood spot sampling. Furthermore, it also allows greater frequency of blood sampling, with minor discomfort and without needing a phlebotomist, for analyses that can only be performed in blood samples, with an increased probability to detect and report Adverse Analytical Finding.

Dried blood spots via remote testing as a possible future application in the doping control process

The use of DBS as biological matrix in combination with a novel technical remote testing app specifically developed for the doping control process shows that testing is becoming easier and variable through DBS. Supplemented by the remote testing solution, the system could significantly increase in the unpredictability of test dates and sample quantity.

Recent advances in mass spectrometry for the detection of doping

INTRODUCTION

The analysis of doping control samples is preferably performed by mass spectrometry, because obtained results meet the highest analytical standards and ensure an impressive degree of reliability. The advancement in mass spectrometry and all its associated technologies thus allow for continuous improvements in doping control analysis.

AREAS COVERED

Modern mass spectrometric systems have reached a status of increased sensitivity, robustness, and specificity within the last decade. The improved sensitivity in particular has, on the other hand, also led to the detection of drug residues that were attributable to scenarios where the prohibited substances were not administered consciously but rather by the unconscious ingestion of or exposure to contaminated products. These scenarios and their doubtless clarification represent a great challenge. Here, too, modern MS systems and their applications can provide good insights in the interpretation of dose-related metabolism of prohibited substances. In addition to the development of new instruments itself, software-assisted analysis of the sometimes highly complex data is playing an increasingly important role and facilitating the work of doping control laboratories.

EXPERT OPINION

The sensitive analysis and evaluation of a higher number of samples in a shorter time is made possible by the ongoing developments in mass spectrometry.

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.

Indirect biomarkers of blood doping: A systematic review

The detection of blood doping represents a current major issue in sports and an ongoing challenge for antidoping research. Initially focusing on direct detection methods to identify a banned substance or its metabolites, the antidoping effort has been progressively complemented by indirect approaches. The longitudinal and individual monitoring of specific biomarkers aims to identify nonphysiological variations that may be related to doping practices. From this perspective, the identification of markers sensitive to erythropoiesis alteration is key in the screening of blood doping. The current Athlete Biological Passport implemented since 2009 is composed of 14 variables (including two primary markers, i.e., hemoglobin concentration and OFF score) for the hematological module to be used for indirect detection of blood doping. Nevertheless, research has continually proposed and investigated new markers sensitive to an alteration of the erythropoietic cascade and specific to blood doping. If multiple early markers have been identified (at the transcriptomic level) or developed directly in a diagnostics' kit (at a proteomic level), other target variables at the end of the erythropoietic process (linked with the red blood cell functions) may strengthen the hematological module in the future. Therefore, this review aims to provide a global systematic overview of the biomarkers considered to date in the indirect investigation of blood doping.

Capillary blood as a complementary matrix for doping control purposes. Application to the definition of the individual longitudinal profile of IGF-1

We present a novel procedure to monitor the fluctuations of the levels of IGF-1 in capillary blood in the framework of doping control analysis. Being an endogenous hormone, direct methods are not applicable, so the most effective way to detect the intake of the exogenous hormone would be based on the longitudinal monitoring of the athlete. We have therefore followed the individual variability, in four subjects (two males and two females), of the levels of IGF-1 in capillary blood samples collected three times per day for five days, then once a week for at least two months. Analyses were performed by liquid chromatography coupled to tandem mass spectrometry following a bottom-up approach. The whole protocol, from the sample collection to the instrumental analysis, was validated according to the World Anti-Doping Agency's guidelines and ISO17025. The analytical protocol showed to be fit for purpose in terms of sensitivity (LOD 25 ng/mL and LOI 35 ng/mL), selectivity (no interferences were detected at the retention time of IGF-1 and the internal standard), and repeatability (CV<10%). The linearity was confirmed in the range of 50-1000 ng/mL (correlation coefficient R² >0.995, with a % relative bias of the experimental concentration of the different calibrators used for the estimation of the linearity lower than 20% for the lowest level and than 15% for the other levels). Stability studies were also performed, also to establish the optimal conditions for transport and storage: samples were stable at 4 °C for up to 72 h and at -20 °C and -80 °C for up to three months. Our preliminary results indicate that, in all subjects, the levels of IGF-1 did not present significant circadian fluctuations and remained stable during the entire period of the study (2-3 months, depending on the subject). The stability over time of IGF-1 levels in capillary blood indicates the possibility of detecting the intake of the non-endogenous hormone based on a longitudinal approach, as it is modeled in the framework of the endocrinological module of the athlete biological passport.

DropWise: current role and future perspectives of dried blood spots (DBS), blood microsampling, and their analysis in sports drug testing

For decades, blood testing has been an integral part of routine doping controls. The breadth of information contained in blood samples has become considerably more accessible for anti-doping purposes over the last 10 years through technological advancements regarding analytical instrumentation as well as enhanced sample collection systems. Particularly, microsampling of whole blood and serum, for instance as dried blood spots (DBS), has opened new avenues in sports drug testing and substantially increased the availability and cost-effectiveness of doping control specimens. Thus, microvolume blood specimens possess the potential to improve monitoring of blood hormone and drug levels, support evaluation of circulating drug concentrations in competition, and enhance the stability of labile markers and target analytes in blood passport analyses as well as peptide hormone and steroid ester detection. Further, the availability of the fraction of lysed erythrocytes for anti-doping purposes warrants additional investigation, considering the sequestering capability of red blood cells (RBCs) for certain substances, as a complementary approach in support of the clean sport.

UHPLC-HRMS Method for the Simultaneous Screening of 235 Drugs in Capillary Blood for Doping Control Purpose: Comparative Evaluation of Volumetric and Non-volumetric Dried Blood Spotting Devices

We present a quick and simple multi-targeted analytical workflow based on ultra-high-performance liquid chromatography coupled to high-resolution mass spectrometry for the screening in dried blood spots and dried plasma spots of a wide variety of drugs with different chemical properties. Seven different microsampling devices were evaluated in view of their application for the detection of the selected target analytes in the framework of doping control analysis. The extraction of the analytes was optimized by assessing the efficacy of protocols based on ultrasonication with aqueous buffers and/or organic solvents of different polarities. Optimal recoveries were obtained by using pure methanol or mixtures of methanol/acetonitrile and methanol/isopropanol, depending on both the device and the target analytes. The method was fully validated according to both ISO17025 and the requirements of the World Anti-Doping Agency: all the analytes were clearly distinguishable from the matrix, with limits of detection in the range of 0.1-3.0 ng mL^-1. Stability studies simulating the storage of samples before the analysis and in view of a possible re-analysis showed that most of the analytes were stable for at least 24 h at 50 °C and for at least 3 weeks at 25 and at 4 °C. The real applicability of the method was assessed by analyzing the samples collected after the administration of two model drugs, acetazolamide and deflazacort. The performance of the method was confirmed to be fit for purpose, and data obtained in blood can also be used to complement those available in urine, allowing to refine the knowledge concerning the pharmacokinetic profiles.

Probing for factors influencing exhaled breath drug testing in sports- Pilot studies focusing on the tested individual's tobacco smoking habit and sex

RATIONALE

Exhaled breath (EB) was found to be a promising matrix in the field of sports drug testing due to the non-invasive and non-intrusive sampling procedure, but significant inter-individual variations regarding detected drug concentrations have been observed in previous studies. To investigate whether the detectability of doping agents in EB is affected by sex or tobacco smoking, two administration studies were conducted with male and female smokers and nonsmokers concerning the elimination of the beta blocker propranolol and the stimulant pseudoephedrine into EB.

METHODS

Following the administration of 40 mg propranolol or 30 mg pseudoephedrine, a total of 19 participants, including female and male nonsmokers as well as female and male smokers, collected EB and dried blood spot (DBS) samples over a period of 24 h. Respective analyte concentrations were determined using liquid chromatography and high-resolution tandem mass spectrometry, and semi-quantitative assays were characterized with regard to selectivity, limit of detection and identification, precision, linearity, and carryover.

RESULTS

Both propranolol and pseudoephedrine were identified in post-administration EB samples from female and male nonsmokers as well as female and male smokers, and the maximum detected drug levels ranged from 9 to 2847 pg/cartridge for propranolol and from 26 to 4805 pg/cartridge for pseudoephedrine. The corresponding DBS levels were in a range of 4-30 ng/mL for propranolol and 55-186 ng/mL for pseudoephedrine.

CONCLUSIONS

Neither the consumption of cigarettes nor the sex appears to represent a decisive criterion as to the detectability of propranolol or pseudoephedrine in EB, but inter-individual variations regarding the detected drug levels were observed among all studied population groups.

Annual banned-substance review: Analytical approaches in human sports drug testing 2020/2021

Most core areas of anti-doping research exploit and rely on analytical chemistry, applied to studies aiming at further improving the test methods' analytical sensitivity, the assays' comprehensiveness, the interpretation of metabolic profiles and patterns, but also at facilitating the differentiation of natural/endogenous substances from structurally identical but synthetically derived compounds and comprehending the athlete's exposome. Further, a continuously growing number of advantages of complementary matrices such as dried blood spots have been identified and transferred from research to sports drug testing routine applications, with an overall gain of valuable additions to the anti-doping field. In this edition of the annual banned-substance review, literature on recent developments in anti-doping published between October 2020 and September 2021 is summarized and discussed, particularly focusing on human doping controls and potential applications of new testing strategies to substances and methods of doping specified in the World Anti-Doping Agency's 2021 Prohibited List.

Sports drug testing and the athletes' exposome

Similar to the general population, elite athletes are exposed to a complex set of environmental factors including chemicals and radiation and also biological and physical stressors, which constitute an exposome that is, unlike for the general population, subjected to specific scrutiny for athletes due to applicable antidoping regulations and associated (frequent) routine doping controls. Hence, investigations into the athlete's exposome and how to distinguish between deliberate drug use and different contamination scenarios has become a central topic of antidoping research, as a delicate balance is to be managed between the vital and continually evolving developments of sensitive analytical techniques on the one hand, and the risk of the athletes' exposome potentially causing adverse analytical findings on the other.

Steroid profiling by UHPLC-MS/MS in dried blood spots collected from healthy women with and without testosterone gel administration

The quantification of a large panel of endogenous steroids in serum by LC-MS/MS represents a powerful clinical tool for the screening or diagnosis of diverse endocrine disorders. This approach has also demonstrated excellent sensitivity for the detection of testosterone misuse in the anti-doping field, especially in female athlete population. In both situations, the use of dried blood spots (DBS) could provide a viable alternative to invasive venous blood collection. Here, the evaluation of DBS sampling for the quantification of a panel of endogenous steroids using UHPLC-MS/MS is described. The UHPLC-MS/MS method was validated for quantitative analysis of eleven free and eight conjugated steroids and was then used for the analysis of DBS samples collected in 14 healthy women during a normal menstrual cycle (control phase) followed by a 28-days testosterone gel treatment (treatment phase). Results were compared with those obtained from serum matrix. Satisfactory performance was obtained for all compounds in terms of selectivity, linearity, accuracy, precision, combined uncertainty, stability as well as extraction recovery and matrix effects. In control phase, high correlation was observed between DBS and serum concentrations for most compounds. In treatment phase, higher testosterone concentrations were observed in capillary than in venous DBS, suggesting a possible interference resulting from testosterone contamination on finger(s) used for gel application. Steroid profiling in capillary DBS represents a simple and efficient strategy for monitoring endogenous steroid concentrations and their fluctuation in clinical context of steroid-related disorders, or for the detection of testosterone abuse in anti-doping.

Dried blood spots in doping analysis

A series of dried blood spot (DBS) detection methods for doping agents have been developed in the last two decades. The DBS technique minimizes invasiveness and reduces storage and shipping costs. Recently, the World Anti-Doping Agency announced the use of DBS for the 2022 Beijing Winter Olympic Games and Paralympic Games owing to the advantages of the DBS application in routine doping control. Therefore the further development of detection methods for doping agents in DBS is important and urgent. This review summarizes five aspects of DBS application in doping analysis: sample collection, storage conditions, pretreatment, instrumentation and validation according to the Prohibited List issued by the World Anti-Doping Agency, and proposes some suggestions for future studies of DBS in doping analysis.