Human in vivo metabolism study of LGD-4033

Drug Test Anal. 2018 Nov;10(11-12):1635-1645. doi: 10.1002/dta.2512. Epub 2018 Nov 8.


Selective androgen receptor modulators (SARMs) are an emerging class of therapeutics targeted to cachexia, sarcopenia, and hypogonadism treatment. LGD-4033 is a SARM which has been included on the Prohibited List annually released by the World Anti-Doping Agency (WADA). The aim of the present work was the investigation of the metabolism of LGD-4033 in a human excretion study after administration of an LGD-4033 supplement, the determination of the metabolites' excretion profiles with special interest in the determination of its long-term metabolites, and the comparison of the excretion time of the phase I and phase II metabolites. The results were also compared to those derived from previous LGD-4033 studies concerning both in vitro and in vivo experiments. Supplement containing LGD-4033 was administered to one human male volunteer and urine samples were collected up to almost 21 days. Analysis of the hydrolyzed (with β-glucuronidase) as well as of the non-hydrolyzed samples was performed using liquid chromatography-high resolution mass spectrometry (LC-HRMS) in negative ionization mode and revealed that, in both cases, the two isomers of the dihydroxylated metabolite (M5) were preferred target metabolites. The gluco-conjugated parent LGD-4033 and its gluco-conjugated metabolites M1 and M2 can be also considered as useful target analytes in non-hydrolyzed samples. The study also presents two trihydroxylated metabolites (M6) identified for the first time in human urine; one of them was recently reported in an LGD-4033 metabolism study in horse urine and plasma.

Keywords: LGD-4033; SARM; human doping; liquid chromatography-mass spectrometry; selective androgen receptor modulator.

MeSH terms

  • Androgens / administration & dosage
  • Androgens / analysis
  • Androgens / metabolism*
  • Androgens / urine*
  • Chromatography, Liquid / methods
  • Dietary Supplements / analysis
  • Gas Chromatography-Mass Spectrometry / methods
  • Humans
  • Hydrolysis
  • Male
  • Mass Spectrometry / methods
  • Nitriles / administration & dosage
  • Nitriles / analysis
  • Nitriles / metabolism*
  • Nitriles / urine*
  • Pyrrolidines / administration & dosage
  • Pyrrolidines / analysis
  • Pyrrolidines / metabolism*
  • Pyrrolidines / urine*
  • Substance Abuse Detection / methods


  • 4-(2-(2,2,2-trifluoro-1-hydroxyethyl)pyrrolidin-1-yl)-2-(trifluoromethyl)benzonitrile
  • Androgens
  • Nitriles
  • Pyrrolidines