Clomiphene and Doping

^{first published 12th July 2023}

Euler L, Mürdter T, Heinkele G, Schwab M, Miller GD, Eichner D, Thomas A, Thevis M.
Identification and synthesis of (Z)-3'-hydroxy clomiphene as a new potential doping-relevant metabolite of clomiphene.
Rapid Commun Mass Spectrom. 2023 Sep 15;37(17):e9599. doi: 10.1002/rcm.9599. PMID: 37580503.

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Abstract

A recent study addressed the possibility of unintentional ingestion of clomiphene through residues in chicken eggs. The method developed here helped distinguish between microdose intake of (E/Z)-clomiphene citrate and consumption of clomiphene-containing eggs by the urinary pattern of four mono-hydroxylated clomiphene metabolites. However, reanalyses of doping-control samples, which showed an adverse analytical finding for clomiphene, revealed a hydroxy clomiphene (HC) isomer that was not found after microdose intake or after consumption of clomiphene-containing eggs and could not be assigned to any of the available reference compounds. The aim of the present follow-up study was to identify this HC isomer and to characterize this metabolite with respect to its potential properties as long-term metabolite in doping controls.

Methods

(E/Z)-3′-HC and (E/Z)-4′-HC were synthesized involving the McMurry reaction. An ultra-performance liquid chromatography–tandem mass spectrometry (UPLC–MS/MS) method was developed and optimized after a derivatization step with dansyl chloride to separate eight HC isomers. Using this method, urine samples from a controlled clomiphene administration study were analyzed, in which male study participants received therapeutic doses of clomiphene for 30 days and collected urine samples for up to 8 months. Thus, isomer-specific HC elimination profiles could be monitored.

Results

The metabolite previously found in doping-control samples was identified as (Z)-3′-HC. The elimination profiles of the different HCs confirmed previous results, with (Z)-3-HC being the most abundant urinary hydroxy metabolite shortly after administration. A new finding was that the data suggest that (Z)-3′-HC is excreted at higher relative concentrations only several weeks after drug intake.

Conclusion

These findings might be of particular importance in sport drug testing as they can assist in the decision-making process to distinguish between intentional doping and inadvertent exposure to clomiphene via food contamination.