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]-5α-androstan-17β-ol (furazadrol F) and [1′,2′]isoxazolo[4′,3′:2,3]-5α-androstan-17β-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 β-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, 4α-hydroxyfurazadrol 4α-HF and 16α-hydroxy oxidised furazadrol 16α-HOF, whereas the minor confirmed metabolites were furazadrol F, 4β-hydroxyfurazadrol 4β-HF, 16β-hydroxyfurazadrol 16β-HF and 16β-hydroxy oxidised furazadrol 16β-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.

中文翻译：

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呋喃唑醇在灵缇犬体内的代谢

据报道，通过互联网获取的“膳食补充剂”呋喃唑醇样品含有设计合成代谢雄激素类固醇 [1',2']isoxazolo[4',5':2,3]-5α-androstan-17β-ol ( furazadrol F ) 和 [1',2']isoxazolo[4',3':2,3]-5α-androstan-17β-ol (isofurazadrol IF )。这些类固醇含有与 A 环融合的异恶唑，旨在提供合成代谢活性，同时逃避检测，引发人们对该制剂在运动中滥用的可能性的担忧。呋喃唑醇( F : IF , 10:1)的代谢通过体内方法在灵缇犬中进行了研究。尿 II 期呋喃唑醇在受控给药后，代谢物被检测为葡糖苷酸。这些 II 期代谢物通过大肠杆菌β-葡萄糖醛酸酶进行酶解，得到相应的 I 期代谢物。使用合成衍生参考材料库，确认了七种尿呋喃唑醇代谢物的身份。已确认的主要代谢物是异呋喃唑醇IF、4α-羟基呋喃唑醇4α-HF和 16α-羟基氧化呋喃唑醇16α-HOF，而次要确认的代谢物是呋喃唑醇F、4β-羟基呋喃唑醇4β-HF、16β-羟基呋喃唑醇16β-HF和 16β-羟基氧化呋喃唑醇16β-HOF。一种主要的羟基呋喃唑醇和两种二羟基呋喃唑醇代谢物仍未确定。确定了呋喃唑醇F和已确认的主要代谢物的定性排泄曲线、检测限和提取回收率。这些研究确定了呋喃唑醇口服后的关键尿液代谢物，可以将其纳入反兴奋剂实验室的常规筛查中，以帮助监管赛狗。