Verification of the conditions of stability of steroid esters in DBS

Code: DBS20AS5AT

This project deals with the stability of steroid esters on DBS cards, which represent a frequently misused class of prohibited compounds. As is well known, these esters are hydrolyzed by endogenous esterases in the blood (even after sampling in serum or plasma) and this can falsify the results accordingly. Whether and to what extent this cleavage also occurs when using DBS will be investigated here.

Main findings

Anabolic steroids represent one of the most frequently misused class of compounds in sports due to their performance enhancing properties. These steroids are often applied as esters with variable length of the non-polar ester side chain that have a considerable impact of the pharmacology of the drug. These steroid esters are known for their degradation due to endogenous esterases, which are present in blood also after the sampling process. The addition of esterase inhibiting agents (such as sodium fluoride) enables a slight inhibition of the degradation in the sampling device. The present study was conducted to confirm the potential of DBS sampling enabling the storage of DBS samples with subsequent analysis of intact steroid esters. Interestingly, the storage of whole blood samples as DBS (without any esterase inhibitors) will provide a useful approach to ensure better stability during long-term storage compared to classic liquid whole blood samples. Also the application of EDTA whole blood samples (e.g. derived from the athlete biological passport sampling) to DBS cards enables the storage for subsequent analysis of steroid esters. Here, the time period from sampling until spotting should be minimized (e.g. < 2 hours). This study shows also that storage at 4°C or -20°C with a desiccant in the dark provides the best results for all steroid esters. Here even after five months of storage the esters were still detectable on the DBS cards.