Segesterone acetate (USAN) (brand name Nestorone; former developmental code names ST-1435, AC-6844, CS-0411), known more commonly simply as nestorone (or nestoron) and also known as elcometrine, is a steroidal progestin of the 19-norprogesterone group which is used as a hormonal contraceptive in several South American countries. Nestorone is the acetate ester of segesterone, which was never marketed, but is an active metabolite of nestorone. Nestorone is only weakly active orally, and is instead given as a subcutaneous implant. It is more than 100-fold times as potent when delivered subcutaneously relative to orally.

CAS：7759-35-5
中文别名：
英文别名：19-Norpregn-4-ene-3,20-dione,17-hydroxy-16-methylene-,acetate;NESTORONE;17-(ACETYLOXY)-16-METHYLENE-19-NORPREGN-4-ENE-20-DIONE;16-Methylene-17-hydroxy-19-norpregn-4-ene-3,20-dione acetate;Elcometrine;17-Hydroxy-16-methylene-19-norpregn-4-ene-3,20-dione acetate;
分子式：C23H30O4
分子量：370.482
精确质量：370.214
Psa：60.44
Logp：4.1852

UNII：9AMX4Q13CC

密度：1.15g/cm3
沸点：499.3ºC at 760mmHg
闪点：216.2ºC
折射率：1.549