Dimethandrolone (DMA), also known by its developmental code name CDB-1321, is an experimental androgen/anabolic steroid (AAS) and progestogen medication which is under investigation for potential clinical use. Dimethandrolone is an AAS, and hence is an agonist of the androgen receptor, the biological target of androgens like testosterone. It is also a progestin, or a synthetic progestogen, and hence is an agonist of the progesterone receptor, the biological target of progestogens like progesterone. Due to its androgenic and progestogenic activity, dimethandrolone has antigonadotropic effects. It has no estrogenic activity. Dimethandrolone was first described in 1997. It was developed by the Contraceptive Development Branch of the National Institute of Child Health and Human Development, an agency in the United States government. An ester and prodrug of dimethandrolone, dimethandrolone undecanoate (DMAU) (CDB-4521), is under development for potential use as a birth control pill for men and in androgen replacement therapy for men. Anabolic steroid#Adverse effects Dimethandrolone is an AAS, though it has also been described as a selective androgen receptor modulator (SARM). As an AAS, it is a potent agonist of the androgen receptor (AR). Unlike testosterone and various other AAS, dimethandrolone is not metabolized by 5α-reductase. In addition, the 5α-reduced derivative of dimethandrolone, 5α-dihydrodimethandrolone (5α-DHDMA), possesses only 30 to 40% of the potency of dimethandrolone as an agonist of the AR, indicating that dimethandrolone does not require potentiation by 5α-reductase for its activity as an AAS and that even if it were a substrate for 5α-reductase, it would not be potentiated in androgenic tissues like the skin and prostate. As such, dimethandrolone and ester prodrugs of it like DMAU are thought to have a reduced risk of androgenic side effects and conditions such as benign prostatic hyperplasia, prostate cancer, pattern scalp hair loss, and acne relative to testosterone and certain other AAS.