[1][2][3][4][5][6] It was a purified extract of animal material such as horse urine, placenta, and/or amniotic fluid, and contained a non-crystalline mixture of estrogens, including estrone, 17β-estradiol, 17α-estradiol, and/or equilin.

[1][3][5] Estrogenic substances was originally produced from the urine of pregnant women, placenta, and/or amniotic fluid, but by the early 1940s, it was manufactured exclusively from the urine of stallions or pregnant mares, similarly to almost all other estrogen preparations on the market.

[8][9][7][1] Estrogenic substances was marketed under a variety of different brand names including Amniotin (Squibb), Equine Estrogenic Substances (Ayerst), Estrogenic Hormones (Upjohn, others), Estrogenic Substances (Reed & Carnrick, Sharp & Dohme, others), Estrolin (Lakeside), Estromone, Estronat (National Drug), Folestrin (Armour), Follacro (Schieffelin), Menformon (Roche-Organon), Neo-Amniotin (Squibb), Oestroform, Ova-Estrin, Theelestrin, and Urestrin (Upjohn), among others.

[1][2][3][4][6] It was provided in various forms and routes of administration including oil solution and aqueous suspension for intramuscular injection, oral tablets and capsules, vaginal suppositories, and topical ointments.

[1] The medication should additionally be distinguished from estrogen ovarian extracts, which had little activity and were considered to be essentially inactive.