Melengestrol acetate

Melengestrol acetate (INN, USAN), sometimes abbreviated as MGA, is a steroidal progestin and antineoplastic agent. It is not approved for use in humans. Instead it's used as an implantable contraceptive for captive animals in zoos and other refuges, and it's also used as a feed additive to promote growth in cattle, a purpose it is licensed for in the United States and Canada. It is an acetate ester of melengestrol, which in contrast, is not used in either animals or humans.