Elimination profile of dexamethasone in dried blood spots (DBS) following single and multiple oral administration and proposal of the minimum reporting level to distinguish forbidden from allowed administrations in sports drug testing.

Authors

Claudia Bressan, Sergi Coll, Élida Alechaga, Ana Aldea-Perona, Núria Monfort, Rosa Ventura

Published in

European journal of pharmaceutical sciences : official journal of the European Federation for Pharmaceutical Sciences. Pages 107701. Oct 28, 2026. Epub Oct 28, 2026.

Abstract

Glucocorticoids (GC), such as dexamethasone (DEX), are prohibited in sports competitions when administered by systemic routes including oral, injectable, and rectal administrations. Since they remain permitted by other therapeutic routes, Minimum Reporting Levels (MRLs) are required to detect misuse in sports. Although antidoping analyses are mainly performed in urine, increasing interest has recently focused on alternative matrices such as dried blood spots (DBS). In this study, the suitability of DBS for the detection of DEX and the evaluation of its elimination profile was investigated. A liquid chromatography-tandem mass spectrometry method was developed for the quantification of DEX and its main metabolite, 6β-hydroxy-DEX, in DBS. The method showed good linearity, sensitivity, precision, and accuracy, with no significant matrix effects. It was applied to samples collected after oral administration of DEX in healthy male participants following single-dose (4 mg, n=8) and multiple-dose (2 × 2 mg/day for 5 days, n=8) regimens. DEX and its metabolite reached the highest concentrations within the first 4 h post-administration and were generally detectable up to 24 h, without evidence of accumulation after repeated dosing. Cortisol suppression was observed in all participants, confirming the systemic effect of oral DEX administration. Plasma samples collected at the same time points showed similar concentration profiles, suggesting homogeneous distribution of DEX between plasma and red blood cells. Based on the DBS-to-plasma ratio obtained and literature plasma data, an MRL of 2 ng/mL in DBS was proposed to identify prohibited systemic DEX administration during sports competitions.

PMID:
42951216
Bibliographic data and abstract were imported from PubMed on 29 Oct 2026.

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