Volume 13, Issue 2 p. 318-337
RESEARCH ARTICLE

Metabolic studies of selective androgen receptor modulators RAD140 and S-23 in horses

Yat-Ming So

Corresponding Author

Yat-Ming So

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

Correspondence

Yat-Ming So and Emmie N. M. Ho, Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China.

Email: [email protected]; [email protected]

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Jenny K. Y. Wong

Jenny K. Y. Wong

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Timmy L. S. Choi

Timmy L. S. Choi

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Anil Prabhu

Anil Prabhu

Department of Veterinary Regulation, Welfare & Biosecurity Policy, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Brian Stewart

Brian Stewart

Department of Veterinary Regulation, Welfare & Biosecurity Policy, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Adrian F. Farrington

Adrian F. Farrington

Department of Veterinary Clinical Services, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Paul Robinson

Paul Robinson

Department of Veterinary Clinical Services, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Terence S. M. Wan

Terence S. M. Wan

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

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Emmie N. M. Ho

Corresponding Author

Emmie N. M. Ho

Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China

Correspondence

Yat-Ming So and Emmie N. M. Ho, Racing Laboratory, The Hong Kong Jockey Club, Sha Tin Racecourse, Sha Tin, N. T., Hong Kong, China.

Email: [email protected]; [email protected]

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First published: 27 August 2020
Citations: 5

Abstract

This paper describes the studies of the in vitro biotransformation of two selective androgen receptor modulators (SARMs), namely, RAD140 and S-23, and the in vivo metabolism of RAD140 in horses using ultra-high performance liquid chromatography–high resolution mass spectrometry. in vitro metabolic studies of RAD140 and S-23 were performed using homogenised horse liver. The more prominent in vitro biotransformation pathways for RAD140 included hydrolysis, hydroxylation, glucuronidation and sulfation. Metabolic pathways for S-23 were similar to those for other arylpropionamide-based SARMs. The administration study of RAD140 was carried out using three retired thoroughbred geldings. RAD140 and the majority of the identified in vitro metabolites were detected in post-administration urine samples. For controlling the misuse of RAD140 in horses, RAD140 and its metabolite in sulfate form gave the longest detection time in hydrolysed urine and could be detected for up to 6 days post-administration. In plasma, RAD140 itself gave the longest detection time of up to 13 days. Apart from RAD140 glucuronide, the metabolites of RAD140 described herein have never been reported before.