Background:

Norgestimate is a synthetic progesterone analog.

Progesterone, an endogenous steroid and progestogen sex hormone, is involved in the pregnancy, menstrual cycle, and embryogenesis. Progesterone is reported to belong to steroid hormones, and is the major progestogen in the body. Progesterone is also a crucial metabolic intermediate in the production of other endogenous steroids and plays an key role in brain function as a neurosteroid.

In vitro: Norgestimate was found that, unlike other 19-nortestosterone derivatives, showed high selectivity for the progesterone receptor and low androgenic activity. Moreover, norgestimate and its main active metabolite norelgestromin could not bind to or occupy sex hormone-binding globulin [1].

In vivo: The androgenic and the progestational activity of norgestimate were compared in two animal studies. It was found the difference in the pharmacological response in norgestimate treated rats was equivalent to the difference in the exposure of the animals to either directly administered or metabolically derived levonorgestrel [2].

Clinical trial: Norgestimate (brand names Ortho-Cyclen, Ortho Tri-Cyclen, Previfem, Sprintec, Prefest, others) is a steroidal progestin of the 19-nortestosterone group that is clinically used in combination with ethinylestradiol and in combination with estradiol in menopausal hormone replacement therapy [3].

参考文献:
[1] Thomas L.  Lemke; David A. Williams (2008). Foye's Principles of Medicinal Chemistry. Lippincott Williams & Wilkins. pp. 1316–. ISBN 978-0-7817-6879-5.
[2] Kuhnz W, Beier S.  Comparative progestational and androgenic activity of norgestimate and levonorgestrel in the rat. Contraception. 1994 Mar;49(3):275-89.
[3] https://en. wikipedia.org/wiki/Norgestimate