Norethynodrel is a steroidal progestin of the 19-nortestosterone group and an isomer of norethisterone. Norethynodrel is a progesteron agonist with very weak estrogenic activiry. Noretynodrel was introduced in 1957 in Enovid, a combination formulation of noretynodrel and mestranol, for the treatment of gynecological and menstrual disorders.A few years later, in May 1960, Enovid was also approved as the first oral contraceptive.