Norethynodrel is a synthetic progestin.1,2 In vivo, norethynodrel (10 mg/animal per day) reduces fetal implantation and induces fetal resorption in mated female rats.2 Formulations containing norethynodrel have been used as oral contraceptives.
1.Kubli-Garfias, C., GonzÁlez-Mariscal, G., VÁsquez-RamÍrez, R., et al.Bimodal binding and free energy of the progesterone receptor in the induction of female sexual receptivity by progesterone and synthetic progestinsJ. Steroid Biochem. Mol. Biol.13343-50(2013) 2.Davis, B.K.Termination of pregnancy in the rat with norethynodrelNature197308-309(1963)