S-23 (drug)
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| Other names | Mastorin |
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| Formula | C18H13ClF4N2O3 |
| Molar mass | 416.76 g·mol−1 |
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S-23, also known as Mastorin, is an investigational selective androgen receptor modulator (SARM) developed by GTX, Inc as a potential male hormonal contraceptive. It binds to the androgen receptor more strongly than older drugs such as andarine with a Ki of 1.7 nM, and in animal studies it showed both a good ratio of anabolic to androgenic effects, and dose-dependent suppression of spermatogenesis with spontaneous recovery after cessation of treatment.[1][2] It was encountered as a novel designer drug by 2020.[3]
References
- ^ Marhefka CA, Gao W, Chung K, Kim J, He Y, Yin D, et al. (February 2004). "Design, synthesis, and biological characterization of metabolically stable selective androgen receptor modulators". Journal of Medicinal Chemistry. 47 (4): 993–8. doi:10.1021/jm030336u. PMC 2040239. PMID 14761201.
- ^ Jones A, Chen J, Hwang DJ, Miller DD, Dalton JT (January 2009). "Preclinical characterization of a (S)-N-(4-cyano-3-trifluoromethyl-phenyl)-3-(3-fluoro, 4-chlorophenoxy)-2-hydroxy-2-methyl-propanamide: a selective androgen receptor modulator for hormonal male contraception". Endocrinology. 150 (1): 385–95. doi:10.1210/en.2008-0674. PMC 2630904. PMID 18772237.
- ^ "Масторин (S-23)". АИПСИН (in Russian). Retrieved 2 January 2026.