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Tamoxifen Pregnancy and Breastfeeding Warnings

Tamoxifen is also known as: Emblon, Genox, Nolvadex, Nolvadex D, Soltamox, Tamofen, Tamone, Tamosin, Tamoxen, Tamoxifen Hexal

Tamoxifen Pregnancy Warnings

Tamoxifen has been assigned to pregnancy category D. Animal studies of doses at or below human doses have revealed evidence of fetotoxicity, lower incidence of implantation, and an increased incidence of low birth weight. There are no controlled data in human pregnancy. However, the manufacturer reports spontaneous abortions, birth defects, fetal deaths, and vaginal bleeding associated with tamoxifen use during pregnancy. Tamoxifen should only be given during pregnancy when benefit outweighs risk. Tamoxifen has been studied in the treatment of male infertility. While some degree of improvement in sperm concentration has been reported, there is generally no change in the sperm's motility. No convincing evidence of efficacy for the use of tamoxifen in treating male infertility has been reported. This is primarily because tamoxifen has not been shown to be effective in increasing the rate of contraception.

A single case of Goldenhar's syndrome (oculoauriculovertebral dysplasia) in an infant exposed to tamoxifen during the first 26 weeks of gestation has been reported; causality is unknown. A case of ambiguous genitalia in an infant exposed to tamoxifen in utero has also been reported.

See references

Tamoxifen Breastfeeding Warnings

One study (n=150) has reported that tamoxifen was very effective in preventing milk secretion and breast engorgement when administered within two hours after delivery. In this study, no side effects were reported.

There are no data on the excretion of tamoxifen and its metabolites into human milk. However, tamoxifen administration reduces serum prolactin levels following multiple doses and suppresses prolactin release in response to breast stimulation. The manufacturer has stated that because of the potential for serious adverse reactions in nursing infants from tamoxifen, women taking tamoxifen should not breast-feed.

See references

References for pregnancy information

  1. "Product Information. Nolvadex (tamoxifen)." Zeneca Pharmaceuticals, Wilmington, DE.
  2. Cunha GR, Taguchi O, Namikawa R, Nishizuka Y, Robboy SJ "Teratogenic effects of clomiphene, tamoxifen, and diethylstilbestrol on the developing human female genital tract." Hum Pathol 18 (1987): 1132-43
  3. Sigman M, Vance ML "Medical treatment of idiopathic infertility." Urol Clin North Am 14 (1987): 459-69
  4. Kotoulas IG, Cardamakis E, Michopoulos J, Mitropoulos D, Dounis A "Tamoxifen treatment in male infertility .1. effect on spermatozoa." Fertil Steril 61 (1994): 911-4
  5. Cullins SL, Pridjian G, Sutherland CM "Goldenhar's syndrome associated with tamoxifen given to the mother during gestation." JAMA 271 (1994): 1905-6
  6. Tewari K, Bonebrake RG, Asrat T, Shanberg AM "Ambiguous genitalia in infant exposed to tamocifen in utero." Lancet 350 (1997): 183

References for breastfeeding information

  1. Shaaban MM "Suppression of lactation by an antiestrogen, tamoxifen." Eur J Obstet Gynecol Reprod Biol 4 (1975): 167-9
  2. Masala A, Delitala G, Lo Dico G, Stoppelli I, Alagna S, Devilla L "Inhibition of lactation and inhibition of prolactin release after mechanical breast stimulation in puerperal women given tamoxifen or placebo." Br J Obstet Gynaecol 85 (1978): 134-7
  3. "Product Information. Nolvadex (tamoxifen)." Zeneca Pharmaceuticals, Wilmington, DE.

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