The in vivo metabolism of Furazadrol in greyhounds

Samples of the 'dietary supplement' Furazadrol sourced through the internet have been reported to contain the designer anabolic androgenic steroids [1 ',2 ']isoxazolo[4 ',5 ':2,3]-5 alpha-androstan-17 beta-ol (furazadrol F) and [1 ',2 ']isoxazolo[4 ',3 ':2,3]-5 alpha-androstan-17 beta-ol (isofurazadrol IF). These steroids contain an isoxazole fused to the A-ring and were designed to offer anabolic activity while evading detection, raising concerns over the potential for abuse of this preparation in sports. The metabolism of Furazadrol (F:IF, 10:1) was studied by in vivo methods in greyhounds. Urinary phase II Furazadrol metabolites were detected as glucuronides after a controlled administration. These phase II metabolites were subjected to enzymatic hydrolysis by Escherichia coli beta-glucuronidase to afford the corresponding phase I metabolites. Using a library of synthetically derived reference materials, the identities of seven urinary Furazadrol metabolites were confirmed. Major confirmed metabolites were isofurazadrol IF, 4 alpha-hydroxyfurazadrol 4 alpha-HF and 16 alpha-hydroxy oxidised furazadrol 16 alpha-HOF, whereas the minor confirmed metabolites were furazadrol F, 4 beta-hydroxyfurazadrol 4 beta-HF, 16 beta-hydroxyfurazadrol 16 beta-HF and 16 beta-hydroxy oxidised furazadrol 16 beta-HOF. One major hydroxyfurazadrol and two dihydroxyfurazadrol metabolites remained unidentified. Qualitative excretion profiles, limits of detection and extraction recoveries were established for furazadrol F and major confirmed metabolites. These investigations identify the key urinary metabolites of Furazadrol following oral administration, which can be incorporated into routine screening by anti-doping laboratories to aid the regulation of greyhound racing.

Automated summary

Samples of the 'dietary supplement' Furazadrol sourced through the internet have been reported to contain designer anabolic androgenic steroids, raising concerns over potential abuse in sports. Metabolism of Furazadrol in greyhounds revealed key urinary metabolites that can aid anti-doping laboratories in regulating greyhound racing.