1-Ethynyl-1-hydroxy-11a-methyl-1H,2H,3H,3aH,3bH,4H,5H,7H,8H,9H,9aH,9bH,10H,11H,11aH-cyclopenta(a)phenanthren-7-one

DescriptionNorethindrone is a progestin (a synthetic substance with properties similar to progesterone) that is best known as the first female oral contraceptive, or the “pill.”Norethindrone’s global impact on society and culture has made it one of the most important inventions in history.

HistoryThe development of norethindrone as a female oral contraceptive took place indirectly over 30 years as a result of steroid research.This research accelerated in the 1930s when structures and medical applications of steroidal compounds were determined.Steroids are lipids, which include cholesterol, bile salts,and sex hormones,that are characterized by a structure of three fused six-carbon rings and a five-carbon ring. In 1957, both norethindrone and norethynodrel were approved by the Food and Drug Administration (FDA) for treating menstrual problems and infertility. In 1960, the FDA approved Searle's norethynodrel under the trade name Enovid. Norethindrone was approved as an oral contraceptive in 1962 under the trade name Ortho-Novum.

UsesProgestin contraceptives work by producing pregnant-like conditions in a female to preventovulation.During pregnancy, progesterone is released by the placenta during development ofthe fetus.This in turn suppresses development of egg follicles and ovulation. Progestins mimicthis condition and thus prevent or delay ovulation.Oral contraceptives currently use progestinand estrogen in combination to prevent ovulation and thicken cervical mucus.The latter makeit harder for sperm to enter the uterus and for an egg to implant on the uterine wall.

Usesprogestogen

UsesA synthetic progestin

UsesProgesteron. Norethindrone and acetate in combination with estrogen as contraceptive (oral). It is reasonably anticipated to be a human carcinogen

General DescriptionNorethindrone, 17α-ethinyl-19-nortestosterone, and itsΔ5（10）-isomer, norethynodrel, might appear at first glance tobe subtle copies of each other. One would predict that theΔ5（10）-double bond would isomerize in the stomach’s acid tothe Δ4-position. However, the two drugs were actually developedsimultaneously and independently; hence, neither can beconsidered a copy of the other. Furthermore, norethindrone isabout 10 times more active than norethynodrel, indicating that isomerization is not as facile in vivo asone might predict. Although they are less active than progesteronewhen given subcutaneously, they have the importantadvantage of being orally active. The discovery of the potentprogestin activity of 17α-ethinyltestosterone (ethisterone) and19-norprogesterone preceded the development of these potentprogestins. Both are orally active, with the 17α-ethinyl groupblocking oxidation to the less active 17-one. The rich electrondensity of the ethinyl group and the absence of the 19-methylgroup greatly enhance progestin activity. Both compoundswere of great importance as progestin components of oralcontraceptives, although currently, use of norethynodrel isminimal. Norethindrone, USP, and norethindrone acetate,USP, are widely used for all the usual indications of the progestins,as well as being components of oral contraceptives.Because these compounds retain key features of the testosteronestructure, including the 17β-OH, it is not surprisingthat they possess some androgenic side effects.