Segesterone acetate (SGA), sold under the brand name Nestorone among others, is a progestin medication which is used in birth control and in the treatment of endometriosis.

[7][11] It is under development in the United States and Europe as a gel in combination with estradiol or testosterone for use as a method of birth control in women and in men, respectively.

[12][13][14][15] In August 2018, a first-of-its-kind one-year contraceptive vaginal ring containing segesterone acetate in combination with ethinyl estradiol was approved in the United States.

[3][5] In healthy young men, segesterone acetate alone at a dose of 2 to 3 mg/day as a transdermal gel (delivering 200–300 μg/day SGA) for 2 weeks suppressed testosterone levels from ~581 ng/dL to ~276 ng/dL (–52%).

[1][2] However, it has also been reported that the medication is more than 100-fold as potent when delivered via subcutaneous implant relative to oral administration in rats.

[4][26] A combination of segesterone acetate and the estrogen estradiol is under development in a transdermal gel formulation for use as a contraceptive in women by the Population Council in conjunction with Antares Pharma in the United States and Europe.

[12] A combination of segesterone acetate and the estrogen ethinylestradiol in a vaginal ring formulation for use as a one-year contraceptive was developed by the Population Council in multiple regions including Latin America, Europe, and Australia.

[27] It completed phase III clinical trials and [27] was approved in the United States in August 2018.

[4][16] A combination of segesterone acetate and the androgen testosterone is under development as a transdermal gel formulation for use as a hormonal contraceptive in men by the Population Council.

[15][28] In a trial, 100 couples used segesterone/testosterone dermal gel as the sole contraception method, which resulted in no pregnancy.