17α-Allyl-19-nortestosterone

17α-Allyl-19-nortestosterone, also known as 3-ketoallylestrenol or as 17α-allylestr-4-en-17β-ol-3-one, is a progestin which was never marketed. It is a combined derivative of the anabolic–androgenic steroid and progestogen nandrolone (19-nortestosterone) and the antiandrogen allyltestosterone (17α-allyltestosterone). The drug is a major active metabolite of allylestrenol, which is thought to be a prodrug of 17α-allyl-19-nortestosterone.

17α-Allyl-19-nortestosterone has 24% of the affinity of ORG-2058 and 186% of the affinity of progesterone for the progesterone receptor, 4.5% of the affinity of testosterone for the androgen receptor, 9.8% of the affinity of dexamethasone for the glucocorticoid receptor, 2.8% of the affinity of testosterone for sex hormone-binding globulin, and less than 0.2% of the affinity of estradiol for the estrogen receptor. The affinity of 17α-allyl-19-nortestosterone for the androgen receptor was less than that of norethisterone and medroxyprogesterone acetate and its affinity for sex hormone-binding globulin was much lower than that of norethisterone. These findings may help to explain the absence of teratogenic effects of allylestrenol on the external genitalia of female and male rat fetuses.