Noretynodrel

Noretynodrel was formerly used in combination with the estrogen mestranol in the treatment of gynecological and menstrual disorders and as a combined birth control pill. It has also been used in the treatment of endometriosis at high dosages of 40 to 100 mg/day. The medication has been discontinued, and is no longer marketed or used medically. ==Contraindications==

No adverse effects have been observed in breastfeeding infants whose mothers were treated with noretynodrel. Because of this, the American Academy of Pediatrics has considered noretynodrel to be usually compatible with breastfeeding. ==Side effects==

There is a reported case of signs of masculinization in a female infant whose mother was treated with noretynodrel for threatened miscarriage during pregnancy. ==Overdose==

Pharmacodynamics (δ4-noretynodrel), an active metabolite of noretynodrel. Noretynodrel has weak progestogenic activity, weak estrogenic activity, and no or only very weak androgenic activity. It is metabolized in a very similar manner to tibolone, whereas the metabolism of norethisterone differs. Progestogenic activity Noretynodrel is a relatively weak progestogen, with only about one-tenth of the progestogenic activity of norethisterone. suggesting that a 7α-methyl substitution does not interfere with progestogenic activity, 3α- and 3β-hydroxynoretynodrel likely are devoid of affinity for the PR similarly to the 3α- and 3β-hydroxylated metabolites of tibolone. Additionally, noretynodrel has not been found to virilize female fetuses, in contrast to many other testosterone-derived progestins including ethisterone, norethisterone, and norethisterone acetate. However, at least one case of pseudohermaphroditism (virilized genitalia) has been observed that may have been due to noretynodrel. The δ4-isomer metabolite of tibolone shows dramatically and disproportionately increased affinity for the AR relative to norethisterone and noretynodrel (5.7- to 18.5-fold greater than that of norethisterone), indicating that the 7α-methyl group of tibolone markedly increases its androgenic activity and is responsible for the greater androgenic effects of tibolone relative to noretynodrel. The estrogenic activity of 3α- and 3β-hydroxynoretynodrel has never been assessed. As such, aromatization likely does not play a role in the estrogenic activity of tibolone or noretynodrel. Pharmacokinetics Noretynodrel is rapidly absorbed upon oral administration and is rapidly metabolized, disappearing from the circulation within 30 minutes. Some researchers have stated that it is specifically a prodrug of norethisterone. According to other researchers however, there is, due to a lack of research, insufficient data to unequivocally show this to be the case at present. About 1% of an oral dose of noretynodrel is detected in breast milk. The pharmacokinetics of noretynodrel have been reviewed. ==Chemistry==

Noretynodrel, also known as 17α-ethynyl-δ5(10)-19-nortestosterone or as 17α-ethynylestr-5(10)-en-17β-ol-3-one, is a synthetic estrane steroid and a derivative of testosterone. ==History==

Noretynodrel was first synthesized by Frank B. Colton of G. D. Searle & Company in 1952, and this was preceded by the synthesis of norethisterone by Luis E. Miramontes and Carl Djerassi of Syntex in 1951. In 1960, noretynodrel, in combination with mestranol (as Enovid), was introduced in the United States as the first oral contraceptive, and the combination of norethisterone and mestranol followed in 1963 as the second oral contraceptive to be introduced. Noretynodrel was first studied in the treatment of endometriosis in 1961 and was the first progestin to be investigated for the treatment of the condition. ==Society and culture==

Generic names Noretynodrel is the of the drug while norethynodrel is its and . It is also known by its developmental code name SC-4642. Availability Noretynodrel is no longer available in any formulation in the U.S., nor does it appear to still be marketed in any other country. ==See also==