[1][2][3][4] It is a combined derivative of the anabolic–androgenic steroid and progestogen nandrolone (19-nortestosterone) and the antiandrogen allyltestosterone (17α-allyltestosterone).

[1][2][3] The drug is a major active metabolite of allylestrenol, which is thought to be a prodrug of 17α-allyl-19-nortestosterone.

[4][5] 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.

[6][7] 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.

[6] These findings may help to explain the absence of teratogenic effects of allylestrenol on the external genitalia of female and male rat fetuses.