FREE SHIPPING over $40
OVER 9000 FIVE-STAR REVIEWS
5% OFF ALL SUBSCRIPTIONS
100% HAPPINESS GUARANTEE
Analyze Diet
0
Home / Equine Research Bank / Drug Test Anal / Metabolic Studies of Nandrolone Decanoate in Castrated Horse...
Drug testing and analysis2025; doi: 10.1002/dta.3919

Metabolic Studies of Nandrolone Decanoate in Castrated Horses After Intramuscular Administration.

Abstract: This paper describes the studies of the in vitro biotransformation of nandrolone decanoate and its metabolic fate in equine plasma and urine after intramuscular administration to castrated thoroughbred horses. The in vitro metabolic study was performed using homogenised horse liver, and the more prominent in vitro biotransformation pathways were found to include hydrolysis, reduction, oxidation and sulfation, mainly resulting in seven Phase I metabolites and one Phase II metabolite. The administration study of nandrolone decanoate was carried out using three retired thoroughbred geldings, each of which was administered intramuscularly with 800 mg of nandrolone decanoate (Deca-Durabolin) once weekly for three consecutive weeks. Nandrolone decanoate and the majority of the identified in vitro metabolites were detectable in post-administration plasma samples for at least 20 days (last sample collected) after the last administration. Although nandrolone decanoate was not found in any post-administration urine, nandrolone (as a metabolite) and its downstream metabolites can be detected for at least 20 days post-administration (last sample collected). For doping control purpose, nandrolone decanoate itself could be a suitable target analyte in horse plasma for effectively controlling its misuse in equine sports.
© 2025 John Wiley & Sons Ltd.
Get Full Text
Publication Date: 2025-07-01 PubMed ID: 40589378DOI: 10.1002/dta.3919Google Scholar: Lookup
The Equine Research Bank provides access to a large database of publicly available scientific literature. Inclusion in the Research Bank does not imply endorsement of study methods or findings by Mad Barn.
LinkedInCopy
  • Journal Article

Summary

This research summary has been generated with artificial intelligence and may contain errors and omissions. Refer to the original study to confirm details provided. Submit correction.

The research paper focuses on the metabolic study of nandrolone decanoate, a steroid, in castrated horses and its possible misuse in equine sports. The drug was introduced into the horses through intramuscular administration and the metabolic pathway along with the resultant metabolites were studied. The authors suggest nandrolone decanoate could serve as a suitable target for doping control in equine sports.

Metabolic Study In Vitro

  • The first part of the research was dedicated to the in vitro biotransformation of nandrolone decanoate. This transformation was observed using a homogenised horse liver to replicate the possible reactions within the horse’s body.
  • The transformation process included hydrolysis, reduction, oxidation and sulfation. These processes resulted in seven major Phase I metabolites and one Phase II metabolite.

Administration Study of Nandrolone Decanoate

  • The researchers administered three retired thoroughbred geldings, each with 800 mg of nandrolone decanoate (Deca-Durabolin) via intramuscular injection. The administration happened once a week for three consecutive weeks.
  • The goal of this part of the study was to track the presence of nandrolone decanoate and its metabolites in the horse’s plasma and urine after administration of the drug.

Presence and Detection of Nandrolone Decanoate

  • Nandrolone decanoate and most of the identified in vitro metabolites were found to be detectable in post-administration plasma samples for at least 20 days after the final administration.
  • Notably, while nandrolone decanoate itself was not detected in post-administration urine, nandrolone (as a metabolite) and its downstream metabolites were detectable in the urine for a similar duration of 20 days post-administration.

Implications for Doping Control

  • The research suggests that nandrolone decanoate can act as a significant target analyte for doping control in equine sports.
  • Its presence in horse plasma and its measurable duration aid in making it a reliable indicator of potential misuse of the steroid in the sport.

Cite This Article

APA
So YM, Kwok WH, Tang CWY, Wong COL, Wan TSM, Ho ENM. (2025). Metabolic Studies of Nandrolone Decanoate in Castrated Horses After Intramuscular Administration. Drug Test Anal. https://doi.org/10.1002/dta.3919

Publication

Drug testing and analysis
ISSN: 1942-7611
NlmUniqueID: 101483449
Country: England
Language: English

Researcher Affiliations

So, Yat-Ming
  • Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, New Territories, Hong Kong, China.
Kwok, Wai Him
  • Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, New Territories, Hong Kong, China.
Tang, Christina W Y
  • Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, New Territories, Hong Kong, China.
Wong, Celia O L
  • Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, New Territories, Hong Kong, China.
Wan, Terence S M
  • Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, New Territories, Hong Kong, China.
Ho, Emmie N M
  • Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, New Territories, Hong Kong, China.

References

This article includes 29 references
  1. Hemmersbach P, Große J. Nandrolone: A Multi‐Faceted Doping Agent. Handbook of Experimental Pharmacology 195 (2010): 127–154.
    doi: 10.1007/978-3-540-79088-4_6google scholar: lookup
  2. Patanè FG, Liberto A, Maglitto ANM. Nandrolone Decanoate: Use, Abuse and Side Effects. Medicina 56 (2020): 606.
    doi: 10.3390/medicina56110606google scholar: lookup
  3. World Anti‐Doping Agency (WADA). WADA Technical Document – TD2021NA. .
  4. International Federation of Horseracing Authorities (IFHA). Article 6 in the International Agreement on Breeding, Racing and Wagering (IABRW). .
  5. Fédération Equestre Internationale (FEI). 2024 FEI Threshold Substances List. 2024.
  6. Houghton E. Studies Related to the Metabolism of Anabolic Steroids in the Horse: 19‐Nortestosterone. Xenobiotica 7 (1977): 683–693.
    doi: 10.3109/00498257709038698google scholar: lookup
  7. Chapman DI, Close PM, Moss MS. Plasma Concentrations and Urinary Excretion of Nandrolone and/or Its Metabolites After Intramuscular Injection of Nandrolone Phenylpropionate to Horses. Equine Veterinary Journal 14 (1982): 213–218.
    doi: 10.1111/j.2042-3306.1982.tb02397.xgoogle scholar: lookup
  8. Kim JY, Choi MH, Kim SJ, Chung BC. Measurement of 19‐Nortestosterone and Its Esters in Equine Plasma by High‐Performance Liquid Chromatography With Tandem Mass Spectrometry. Rapid Communications in Mass Spectrometry 14 (2000): 1835–1840.
    doi: 10.1002/1097-0231(20001015)14:19<1835::aid-rcm103>3.0.co;2-igoogle scholar: lookup
  9. Anielski P, Thieme D, Schlupp A, Grosse J, Ellendorff F, Mueller RK. Detection of Testosterone, Nandrolone and Precursors in Horse Hair. Analytical and Bioanalytical Chemistry 383 (2005): 903–908.
    doi: 10.1007/s00216-005-0104-8google scholar: lookup
  10. Roig M, Segura J, Ventura R. Quantitation of 17β‐Nandrolone Metabolites in Boar and Horse Urine by Gas Chromatography–Mass Spectrometry. Analytica Chimica Acta 586 (2007): 184–195.
    doi: 10.1016/j.aca.2006.08.033google scholar: lookup
  11. Dehennin L, Bonnaire Y, Plou P. Detection of Nandrolone Administration to the Entire Male Horse by a Provisional Concentration Threshold for Urinary Oestranediol Determined by Gas Chromatography‐Mass Spectrometry. Equine Veterinary Journal 39 (2007): 186–188.
    doi: 10.2746/042516407x170418google scholar: lookup
  12. Kaabia Z, Dervilly-Pinel G, Hanganu F. Ultra High Performance Liquid Chromatography/Tandem Mass Spectrometry Based Identification of Steroid Esters in Serum and Plasma: An Efficient Strategy to Detect Natural Steroids Abuse in Breeding and Racing Animals. Journal of Chromatography a 1284 (2013): 126–140.
    doi: 10.1016/j.chroma.2013.02.010google scholar: lookup
  13. Dehennin L, Bonnaire Y, Plou P. Human Nutritional Supplements in the Horse: Comparative Effects of 19‐Norandrostenedione and 19‐Norandrostenediol on the 19‐Norsteroid Profile and Consequences for Doping Control. Journal of Chromatography B 766 (2002): 257–263.
    doi: 10.1016/s0378-4347(01)00506-0google scholar: lookup
  14. Houghton E, Copsey J, Dumasia MC, Haywood PE, Moss MS, Teale P. The Identification of C‐18 Neutral Steroids in Normal Stallion Urine. Biomedical Mass Spectrometry 11 (1984): 96–99.
    doi: 10.1002/bms.1200110209google scholar: lookup
  15. Dumasia MC, Houghton E. Studies Related to the Metabolism of Anabolic Steroids in the Horse: The Phase I and Phase II Biotransformation of 19‐Nortestosterone in the Equine Castrate. Xenobiotica 14, no. 8 (1984): 647–655.
    doi: 10.3109/00498258409151462google scholar: lookup
  16. Ho ENM, Leung DKK, Wan TSM, Yu NH. Metabolic Studies of Methenolone Acetate in Horses. Analytica Chimica Acta 540 (2005): 111–119.
    doi: 10.1016/j.aca.2004.10.019google scholar: lookup
  17. Leung GNW, Ho ENM, Leung DKK. Metabolic Studies of Clostebol Acetate in Horses. Chromatographia 61 (2005): 397–402.
    doi: 10.1365/s10337-005-0529-4google scholar: lookup
  18. Ho ENM, Leung DKK, Leung GNW. Metabolic Studies of Mesterolone in Horses. Analytica Chimica Acta 596 (2007): 149–155.
    doi: 10.1016/j.aca.2007.05.052google scholar: lookup
  19. Ho ENM, Kwok WH, Leung DKK, Wan TSM, Wong ASY. Metabolic Studies of Turinabol in Horses. Analytica Chimica Acta 586 (2007): 208–216.
    doi: 10.1016/j.aca.2006.09.053google scholar: lookup
  20. Kwok WH, Ho ENM, Leung GNW. Metabolic Studies of 1‐Testosterone in Horses. Drug Testing and Analysis 5 (2012): 81–88.
    doi: 10.1002/dta.1380google scholar: lookup
  21. Leung GNW, Kwok WH, Wan TSM, Lam KKH, Schiff PJ. Metabolic Studies of Formestane in Horses. Drug Testing and Analysis 5 (2013): 412–419.
    doi: 10.1002/dta.1444google scholar: lookup
  22. Wong ASY, Ho ENM, Wan TSM, Lam KKH, Stewart BD. Metabolic Studies of Oxyguno in Horses. Analytica Chimica Acta 891 (2015): 190–202.
    doi: 10.1016/j.aca.2015.08.006google scholar: lookup
  23. Kwok WH, Kwok KY, Leung DKK. Metabolic Study of Androsta‐1,4,6‐Triene‐3,17‐Dione in Horses Using Liquid Chromatography/High Resolution Mass Spectrometry. Journal of Steroid Biochemistry and Molecular Biology 152 (2015): 142–154.
    doi: 10.1016/j.jsbmb.2015.05.011google scholar: lookup
  24. Kwok WH, Kwok KY, Leung DKK. In Vitro Metabolism Studies of Desoxymethyltestosterone (DMT) and Its Five Analogues, and In Vivo Metabolism of Desoxyvinyltestosterone (DVT) in Horses. Journal of Mass Spectrometry 50 (2015): 994–1005.
    doi: 10.1002/jms.3613google scholar: lookup
  25. Choi TLS, Wong JKY, Kwok WH, Curl P, Mechie S, Wan TSM. Metabolic Study of Methylstenbolone in Horses Using Liquid Chromatography‐High Resolution Mass Spectrometry and Gas Chromatography‐Mass Spectrometry. Journal of Chromatography a 1546 (2018): 106–118.
    doi: 10.1016/j.chroma.2018.02.041google scholar: lookup
  26. Tang PW, Crone DL. A New Method for Hydrolyzing Sulfate and Glucuronyl Conjugates of Steroids. Analytical Biochemistry 182 (1989): 289–294.
    doi: 10.1016/0003-2697(89)90596-4google scholar: lookup
  27. Wong JKY, Tang FPW, Wang TSM. In Vitro Metabolic Studies Using Homogenised Horse Liver in Place of Horse Liver Microsomes. Drug Testing and Analysis 3 (2011): 393–399.
    doi: 10.1002/dta.273google scholar: lookup
  28. Wong JKY, Chan GHM, Leung DKK. Generation of Phase II In Vitro Metabolites Using Homogenised Horse Liver. Drug Testing and Analysis 8 (2016): 241–247.
    doi: 10.1002/dta.1850google scholar: lookup
  29. Thomsen V, Schatzlein D, Mercuro D. Limits of Detection in Spectroscopy. Spectroscopy (Eugene, Oreg.) 18 (2003): 112–114.

Citations

This article has been cited 0 times.
Subscribe to our newsletter
Join 99,344 horse owners like you who receive our email updates on horse health and nutrition.