The Sound of Evolution
Norgestrel
Mechanism of action:
Norgestrel is a synthetic progestin and a derivative of 19-nortestosterone. Norgestrel suppresses the hypothalamic-pituitary-gonadal axis through negative feedback, reducing the luteinizing hormone (LH) surge and preventing normal follicular rupture, thereby inhibiting or delaying ovulation. Norgestrel also thickens cervical mucus, making it more difficult for sperm to pass through the cervix into the uterine cavity and reducing the likelihood of fertilization. In addition, norgestrel keeps the endometrium in a thin, non-proliferative state, which makes embryo implantation less favorable even if fertilization occurs.
Reference(s):
1. Hammond GL et al. (2001). Preclinical profiles of progestins used in formulations of oral contraceptives and hormone replacement therapy. Am J Obstet Gynecol.
2. Rabe T et al. (2000). Inhibition of skin 5 alpha-reductase by oral contraceptive progestins in vitro. Gynecol Endocrinol.