Norethynodrel

Norethynodrel is an orally active progestogen analog that reduces estrogen-like effects and enhances progestogen-like responses in endometrial stromal cells. Norethynodrel also promotes cell maturation and predecidual cell formation by inducing organelle hyperplasia and glycogen accumulation. Norethynodrel competitively inhibits drug-metabolizing enzymes in rat liver microsomes, thereby prolonging Pentobarbital sleep time, while exhibiting multiple effects including reduced body weight gain, attenuated heart rate elevation and ovulation inhibition. In mouse models, Norethynodrel significantly increases the incidence of mammary adenocarcinoma, cervical cancer and pituitary tumors. Norethynodrel can be used for mechanism research on related diseases such as mammary adenocarcinoma, cervical cancer, ovarian tubular adenoma and pituitary adenoma^[1][2][3][4]. In Vitro: Norethynodrel (10-100 μM; 20 h) weakly inhibits Sprague-Dawley rat hepatic microsomal pentobarbital hydroxylation (K_i=24 μM), aminopyrine N-demethylation, and aniline p-hydroxylation in vitro, with greater inhibition observed at 100 μM than at 10 μM^[3].
Norethynodrel (10-100 μM) acts as a Type I substrate for Sprague-Dawley rat hepatic microsomal cytochrome P-450, exhibiting a spectral dissociation constant (K_s) of 24 μM and a maximum difference absorbance (ΔAmax) of 0.029^[3]. In Vivo: Norethynodrel (125-500 μg/20 g body weight; s.c.; twice weekly; up to 106 weeks) induces a significant increase in mammary gland development, hyperplastic alveolar nodules, type B mammary adenocarcinomas (8 cases), and cervical carcinomas (6 cases) in virgin female A/J mice, while also causing structural changes in ovaries, uteri, and adrenals^[2].
Norethynodrel (10-50 mg/kg; p.o.; single dose) significantly increases pentobarbital-induced sleep duration in male Sprague-Dawley rats, with sleep times of 134 minutes and 221 minutes respectively, indicating inhibition of hepatic pentobarbital metabolism^[3].
Norethynodrel (10-50 mg/kg; p.o.; daily; 4 days) does not induce hepatic microsomal enzymes in male Sprague-Dawley rats, but significantly reduces daily body weight gain^[3].
Norethynodrel (165 μg/kg/day; s.c.; continuous; 20 weeks) contributes a minor, statistically significant attenuation of isoproterenol-induced heart rate increases in female rats at specific time points, with ethinyl estradiol driving the primary attenuation effect^[4].