title: Progestagenic and antigonadotrophic activities of STS 557.
abstract: STS 557 (17 alpha-cyanomethyl-17 beta-hydroxy-estra-4, 9-dien-3-one) was tested for progestagenic activity in rabbits and for ovulation-inhibiting activities in rabbits and rats in comparison with levonorgestrel and, in some cases, with norethisterone acetate or chlormadinone acetate. In the immature rabbit, the endometrium transformation-inducing activity of STS 557 was about 5 times higher than levonorgestrel for both oral and subcutaneous administration. The ovulation-inhibiting effect of STS 557 was 3.5 times higher than that of levonorgestrel in the rabbit after oral administration, and about 7 times higher in the rat. After subcutaneous injection, however, the antiovulatory activity of STS 557 in rats was only about 4% of that of levonorgestrel when the ED 50 were compared.
mesh_terms: D000284:Administration, Oral; D000818:Animals; D002715:Chlormadinone Acetate / Q000494:pharmacology; D003277:Contraceptives, Oral, Combined / Q000494:pharmacology; D005260:Female; D006062:Gonadotropins / Q000037:antagonists & inhibitors*; D007279:Injections, Subcutaneous; D016912:Levonorgestrel; D009277:Nandrolone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009640:Norethindrone / Q000494:pharmacology; D009644:Norgestrel / Q000494:pharmacology; D010060:Ovulation / Q000187:drug effects; D045167:Progesterone Congeners; D011817:Rabbits; D051381:Rats; D011919:Rats, Inbred Strains; D013045:Species Specificity
chemical_list: D003277:Contraceptives, Oral, Combined; D006062:Gonadotropins; D045167:Progesterone Congeners; D002715:Chlormadinone Acetate; D009644:Norgestrel; C023635:dienogest; D016912:Levonorgestrel; D009277:Nandrolone; D009640:Norethindrone