Norethindrone is a form of progesterone, which is a female hormone involved in conception. Norethindrone is used to prevent pregnancy by inhibiting ovulation (the release of an egg from an ovary); by causing the cervical mucous to thicken, which makes it harder for sperm to move toward the uterus; and by affecting other hormones, the fallopian tubes and the lining of the uterus. Norethindrone is used to prevent pregnancy.
Norethindrone mimics the female hormone progesterone and prevents pregnancy. Up until recently it could only be taken orally, but now it is available in the form of a patch where it can be absorbed by the skin directly into the blood stream, although this is a less reliable method of use. This compound can also be used in hormone replacement therapy during the menopause to inhibit the symptoms that this induces. Norethindrone transforms proliferative endometrium into secretory endometrium. It inhibits (at the usual dose range) the secretion of pituitary gonadotropins, which in turn prevents follicular maturation and ovulation. It may also demonstrate some estrogenic, anabolic or androgenic activity but should not be relied upon. Norethindrone prevents ovulation, probably by inhibiting secretion of pituitary hormones that in turn regulate menstrual and reproductive cycles. Norethindrone also alters activity of uterine cells, resulting in, among other changes, thickening of the cervical mucus. These changes make it less likely for a partner's sperm to reach and fertilize an egg.
The molecular formula of Norethindrone is C20H26O2, and it has a molecular mass of 298.42, although its’ exact mass is 298.19. The melting point of this compound is between 203 ° C and 204 ° C, and it has a chemical name of 17-hydroxy-19-nor-17alpha-pregn-4-en-20-yn-3-one.
Norethindrone is used for the treatment of menstrual or uterine disorders caused by progestin imbalance, such as secondary amenorrhea (failure to menstruate), endometriosis, and abnormal uterine bleeding. Secondary amenorrhea is the cessation of the menstrual period in women who have previously menstruated, which is sometimes caused by a hormonal imbalance.
Norethindrone acetate differs from norethindrone only in potency; the acetate is approximately twice as potent.