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Letrozole / ribociclib Pregnancy and Breastfeeding Warnings

Letrozole / ribociclib is also known as: Kisqali Femara Co-Pack

Medically reviewed on Apr 25, 2018

Letrozole / ribociclib Pregnancy Warnings

Combination Therapy (letrozole and ribociclib) and Monotherapy (ribociclib):
-Based on findings in animals and the mechanism of action, this drug may cause fetal harm.
-US FDA pregnancy category: Not Assigned

Monotherapy (letrozole):
-Contraindicated in women who are or may become pregnant.
-US FDA pregnancy category: X

-Apprise pregnant patients or those who become pregnant during treatment that this drug may cause fetal harm.
-Obtain a pregnancy test in females of reproductive potential prior to treatment initiation.
-Advise females of reproductive potential to use effective contraception (methods that result in less than 1% pregnancy rates) during treatment and for at least 3 weeks after the last dose.
-Animal studies indicate the potential for fertility impairment in both males and females.

Isolated cases of birth defects (labial fusion, ambiguous genitalia) have been reported in pregnant women exposed to letrozole. Animal data with letrozole have revealed evidence of embryotoxicity, fetotoxicity, and teratogenicity with doses much smaller than the daily maximum recommended human dose on a mg/m2 basis. Adverse effects included intrauterine mortality, pre- and post-implantation pregnancy loss and resorptions, fewer live fetuses, congenital malformations affecting the renal and skeletal systems, and reduced fertility including decreased incidence of successful mating and pregnancy, sexual inactivity in females, and reproductive tract atrophy in males and females.

Animal studies with ribociclib have shown reduced maternal body weight gain, reduced fetal weights (accompanied by skeletal changes), and increased incidences of post-implantation loss and fetal abnormalities (malformations, and external, visceral, and skeletal variants) at exposures approximately 0.6 and 1.5 times the exposure in humans at the highest recommended dose of 600 mg/day based on AUC. Administration of ribociclib to animals also resulted in atrophic changes in testes (e.g., degeneration of seminiferous tubular epithelia in the testes; hypospermia, luminal cellular debris, and vacuolation of epithelia in the epididymides) with a trend towards reversibility after a 4-week non-dosing period. There are no controlled data in human pregnancy.

US FDA pregnancy category X: Studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits.

US FDA pregnancy category Not Assigned: The US FDA has amended the pregnancy labeling rule for prescription drug products to require labeling that includes a summary of risk, a discussion of the data supporting that summary, and relevant information to help health care providers make prescribing decisions and counsel women about the use of drugs during pregnancy. Pregnancy categories A, B, C, D and X are being phased out.

See references

Letrozole / ribociclib Breastfeeding Warnings

Breastfeeding is not recommended during treatment and for at least 3 weeks after the last dose.

Excreted into human milk: Unknown
Excreted into animal milk: Yes

-Ribociclib and its metabolites readily pass into the milk of lactating animals.
-The effects in the nursing infant and on milk production for both ribociclib and letrozole are unknown.

In lactating animals administered a single ribociclib dose of 50 mg/kg, drug exposure was 3.56-fold higher in milk compared to maternal plasma. Animal data with letrozole have shown doses as low as 0.003 mg/kg/day (approximately 0.01 the maximum recommended human dose on a mg/m2 basis) administered on day 0 to day 20 of lactation resulted in impaired reproductive performance of the male offspring (as reflected by decreased mating and pregnancy ratios), but no effects on the reproductive performance of female offspring were observed.

See references

References for pregnancy information

  1. "Product Information. Kisqali Femara Co-Pack (letrozole-ribociclib)." Novartis Pharmaceuticals, East Hanover, NJ.
  2. "Product Information. Femara (letrozole)." Novartis Pharmaceuticals, East Hanover, NJ.
  3. "Product Information. Kisqali (ribociclib)." Novartis Pharmaceuticals, East Hanover, NJ.

References for breastfeeding information

  1. "Product Information. Kisqali Femara Co-Pack (letrozole-ribociclib)." Novartis Pharmaceuticals, East Hanover, NJ.

Further information

Always consult your healthcare provider to ensure the information displayed on this page applies to your personal circumstances.