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

Abstract

Capillary blood sampled as dried blood spot (DBS) has shown substantial potential as test matrix in sports drug testing in various different settings, enabling the analysis of numerous different drugs and/or their respective metabolites. In addition to established beneficial aspects of DBS specimens in general (such as the minimally invasive and non‐intrusive nature, and simplified sample transport), a yet unexplored advantage of DBS in the anti‐doping context could be the opportunity of preserving a source of information complementary to routine doping controls performed in urine or venous blood. Whenever follow‐up investigations are warranted or required, frequently collected and stored (but yet not analyzed) DBS samples could be target‐tested for the compound(s) in question, in order to contribute to results management and decision‐making processes.

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

“…The LODs ranged from 0.1 to 3.0 ng mL –1 (see again Tables –), low enough to detect the abuse of the compounds under investigation in the occasion of doping control tests according to the data reported in the literature. − …”

“…Dried blood spots (DBSs) are a form of bio-samples in which capillary blood by fingertip or arm pricking is applied onto marked circles on untreated/treated cellulose paper or adsorbed on specially manufactured volumetrically controlled polymer-based tips or dots. − Since its introduction, the use of DBS, as an alternative matrix, has been progressively extending, now covering many different applications, including therapeutic drug monitoring, forensic analysis, and, more recently, doping analysis. − Indeed, DBS provide several advantages compared to conventional venous blood samples: (i) the procedure for the collection of the sample is simplified and minimally invasive, so that it can be successfully performed even by minimally trained personnel, (ii) it offers favorable stability of many analytes, (iii) the collection process reduces the risk of infection, (iv) the risk of bacterial contamination or hemolysis is minimal, (v) the collection devices are generally low cost; and finally (vi) the storage and transport of samples are easier and without additional costs associated with the need of ensuring a rigid temperature control along the chain of custody. ,, Nonetheless, different challenges also need to be faced when DBSs are used and primarily among them are as follows: (i) to ensure a sufficient quality of the spot (mainly in terms of size and homogeneity), (ii) to allow a satisfying recovery of all the target analytes in the case of multi-targeted assays, a critical parameter given the reduced available volume of the sample, (iii) to assess the relevance of hematocrit effects, possibly influencing the analyte concentration and recovery in the case of quantitative determinations, (iv) to take into account the blood-to-plasma ratio (that provides an indication of the binding to erythrocytes of the target analytes), (v) to optimize the timing and procedure for the addition of the internal standard, indispensable in the case of quantitative determinations, (vi) to avoid the loss of volatile or photodegradable analytes, and finally (vii) to specifically consider the effects on the integrity of the sample of environmental conditions, primarily humidity and bacterial growth. ,,− For the above reasons, different countermeasures were proposed, including (i) the use of plastic bags containing adequate desiccants (i.e., silica gel and bentonite) and humidity indicators, (ii) the use of calibrated capillaries and of volumetric microsampling devices, in the aim to increase the repeatability and reproducibility of the spots, (iii) the use of dried plasma spots (DPSs), in order to overcome multiple hematocrit effects and plasma-to-blood ratio issues, and finally (iv) the measurement of hematocrit directly on the DBS cards to control multiple hematocrit effects. − …”

Sports drug testing and the athletes' exposome

“…Protecting athletes from consequences due to inadvertent doping has become particularly challenging, especially when considering the required and continuously improving analytical sensitivity of antidoping testing procedures 94 . 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, and although it might appear as counterintuitive at first glance, increasing the testing frequency of athletes seems to be a particularly useful approach in support of the differentiation of low (lowest) level drug exposure from applications of pharmacologically relevant doses of doping agents 95 . Further, “pharmacokinetic outliers,” that is, drugs with for instance particularly long elimination periods and corresponding detection windows 96–104 and substances causing doping control urine samples to appear atypical or suspicious 105–110 necessitate continued consideration.…”

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

“…Currently, mainly urine samples, which provide a broad analyte spectrum and long detection windows due to the detection of metabolites, and, to a lesser extent, blood samples are used for analytical purposes 4–6 . Recently, dried blood spots (DBS) have been introduced as a useful additional matrix for doping controls 7–16 . Urine samples are collected under visual control, invading the privacy of athletes, 17 whereas blood collection is an invasive procedure, or in the case of DBS, a minimally invasive procedure 18 .…”

“…[4][5][6] Recently, dried blood spots (DBS) have been introduced as a useful additional matrix for doping controls. [7][8][9][10][11][12][13][14][15][16] Urine samples are collected under visual control, invading the privacy of athletes, 17 whereas blood collection is an invasive procedure, or in the case of DBS, a minimally invasive procedure. 18 Besides analytical aspects, the sampling procedure is a major concern when alternative matrices are examined and established.…”