Norethynodrel use while Breastfeeding

Norethynodrel Levels and Effects while Breastfeeding

Summary of Use during Lactation

Norethynodrel is only available in the United States in combination oral contraceptive products. Based on the available evidence, expert opinion holds that nonhormonal methods are preferred during breastfeeding and progestin-only contraceptive are preferred over combined oral contraceptives in breastfeeding women, especially during the first 4 weeks postpartum. For further information, consult the record entitled, "Contraceptives, Oral, Combined."

Drug Levels

Norethynodrel is a prodrug that is rapidly converted to norethindrone in the body.[1]

Maternal Levels. In one old study using a nonspecific radiolabeling assay technique, 2 women were found to excrete 0.0044% and 0.13% of an administered dose (not weight-adjusted) of norethynodrel into breastmilk.[2]

In another study using radioactive labeled norethynodrel, 4 women who were between days 4 and 6 postpartum excreted an average of 1.1% (range 0.45 to 1.52%) of a dose (not weight-adjusted) into breastmilk.[3]

Infant Levels. Relevant published information was not found as of the revision date.

Effects in Breastfed Infants

Abnormal breast enlargement was reported in a 3-week-old male breastfed infant whose mother was taking an oral contraceptive containing norethynodrel 25 mg and mestranol 100 mcg.[4] The contraceptive was the probable cause of breast enlargement, but most likely the estrogen component mestranol rather than norethynodrel caused the effect.

Possible Effects on Lactation

Relevant published information was not found as of the revision date. However, progestins such as norethynodrel are not considered to suppress lactation.

Alternate Drugs to Consider

Etonogestrel, Levonorgestrel, Medroxyprogesterone Acetate, Norethindrone

References

1. Orme ML, Back DJ, Breckenridge AM. Clinical pharmacokinetics of oral contraceptive steroids. Clin Pharmacokinet. 1983;8:95-136. PMID: 6342899

2. Pincus G, Bialy G et al. Radioactivity in the milk of subjects receiving radioactive 19-norsteroids. Nature. 1966;212:924-5. PMID: 6012386

3. Laumas KR, Malkani PK et al. Radioactivity in the breast milk of lactating women after oral administration of 3H-norethynodrel. Am J Obstet Gynecol. 1967;98:411-3. PMID: 5630224

4. Curtis EM. Oral-contraceptive feminization of a normal male infant. Obstet Gynecol. 1964;23:295-6. PMID: 14117345

Norethynodrel Identification

Substance Name

Norethynodrel

CAS Registry Number

68-23-5

Drug Class

• Contraceptive Agents, Female
• Contraceptives, Oral, Synthetic

Administrative Information

LactMed Record Number

468

Information from the National Library of Medicine's LactMed Database.

Last Revision Date

2010-07-09

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