Study summary · research use only
Characterization of equine liver microsome-generated metabolites of growth hormone secretagogue small molecule ibutamoren
Plain-language summary
Paraphrased from the published abstract below — not a verdict on whether anything works.
This study used equine liver microsomes to characterize metabolites of ibutamoren, an orally active non-peptide growth hormone secretagogue, employing high-performance liquid chromatography with a QExactive high-resolution mass spectrometer. The authors detected 32 metabolites (20 phase I and 12 phase II). Findings included that ibutamoren was prone to oxidation, producing hydroxylated metabolites; dissociation of the phenyl ring and 2-amino-2-methylpropanamide side chain was observed; glucuronic acid conjugates of mono-, di-, and trihydroxylated analogues were detected; and no sulfonic acid conjugated metabolites were observed. The authors state these data may help in detection of ibutamoren and reveal its use in competitive sports.
Abstract
Interest in growth hormone secretagogues has intensified during the past several years based on capable, ever-widening investigational applications of recombinant growth hormone in animals and humans. Ibutamoren is a potent, long-acting, selective and orally active non-peptide growth hormone secretagogue, which has a great potential for abuse as a performance-enhancing agent in sports. To support drug metabolism and pharmacokinetic studies of chiral pharmaceuticals, it is necessary to combine the resolving power of high-performance liquid chromatography with the sensitivity of mass spectrometric techniques. This paper describes the metabolic conversion of ibutamoren using equine liver microsomes and metabolite characterization using a QExactive high-resolution mass spectrometer. A total of 32 metabolites for ibutamoren (20 phase I and 12 phase II) were detected. The important findings of the current research are as follows: (1) the growth hormone secretagogue ibutamoren was prone to oxidation, resulting in corresponding hydroxylated metabolites; (2) in ibutamoren, the dissociation of the phenyl ring and 2-amino-2-methylpropanamide side chain was also observed; (3) the glucuronic acid conjugates of mono-, di- and trihydroxylated analogues were detected; and (4) no sulfonic acid conjugated metabolites were observed in this study of ibutamoren. The reported data help in the speedy detection of the growth hormone secretagogue ibutamoren and reveal its illegal use in competitive sports.
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