Background: Budesonide (22(R,S)-16α,17α-butylidenedioxy-11β,21-dihydroxypregna-1,4-diene-3,20-dione) (BUD) is a glucocorticoid widely used for the treatment of asthma and rhinitis. Its use in sport competitions is prohibited when administered by oral, intravenous, intramuscular, or rectal routes, but its use by other routes (eg, inhalation) is allowed. The objective of this study was to evaluate the urinary profiles of different metabolites of BUD after oral and inhaled administrations in order to define a criterion to discriminate between forbidden and authorized administrations of the drug.
Methods: A liquid chromatography-tandem mass spectrometry method was validated to quantify BUD, 16α-hydroxy-prednisolone, 6β-hydroxy-budesonide, and 6α-hydroxy-budesonide and to qualitatively determine 13 additional BUD metabolites. The method was applied to urine samples collected in clinical studies where BUD was administered to healthy volunteers by the oral route (n = 2) and by inhalation for 3 consecutive days followed by a single oral dose (n = 8).
Results: Reporting levels of the different metabolites were evaluated in terms of specificity (no false-positive results after inhalation) and sensitivity (no false-negative results after oral intake).
Conclusion: Taking into consideration the administered doses, the best compromise to discriminate between authorized inhaled administration and forbidden oral intake of BUD was found using a reporting level of 20 ng/mL of metabolite 6β-hydroxy-budesonide.