Ethisterone is a synthetic steroid hormone that has progestogenic and androgenic activity. Its chemical name is pregneninolone acetate, and it is used in some medical treatments, such as for certain types of breast cancer and for the treatment of menstrual disorders. It is not commonly used today due to the availability of other hormonal therapies with more favorable side effect profiles. As with any medication, it should only be used under the guidance of a healthcare professional.