[{"from": "human", "value": "Please give me some details about this molecule. [C][C@][C][C][C@H1][C@H1][Branch1][=C][C@@H1][Ring1][=Branch1][C][C][C@][Ring1][=Branch2][Branch1][Ring1][C][#C][O][C][C][C][=C][C][=Branch1][C][=O][C][C][C@H1][Ring2][Ring1][C][Ring1][#Branch1]"}, {"from": "gpt", "value": "The molecule is a synthetic progestational hormone belonging to the 19-nortestosterone-derived class of progestins. It is further classified as a second-generation progestin, along with [levonorgestrel] and its derivatives, and is the active form of several other progestins including [norethynodrel] and [lynestrenol]. Norethisterone mimics the actions of endogenous [progesterone], albeit with a greater potency, and is used on its own or in combination with estrogen derivatives in a variety of applications including contraception and hormone replacement therapy. First derived in 1951 in Mexico City, norethisterone was originally intended for use as a remedy for irregular menstruation and endometriosis, and was not marketed for use as an oral contraceptive until 1962."}]