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Contraindication of Femara (Letrozole) in Premenopausal Women
DORVAL, QC -- November 28, 2005 -- Following discussions with Health Canada, Novartis is advising health care professionals of concerns about the use of the aromatase inhibitor Femara* (letrozole) for the purpose of ovulation induction in the treatment of infertility.
Novartis is aware that Femara* has been or is being used to treat infertility even though statements in the Canadian Product Monographs warn physicians about potential embryo- and fetotoxicity with or without teratogenicity.
There have been post-market reports of congenital anomalies in infants of mothers exposed to Femara* for the treatment of infertility.
Novartis remind all concerned physicians that the use of letrozole for the purpose of ovulation induction is not within the scope of the approved indications.
Indications and Clinical Use
Femara* (letrozole) is indicated for the treatment of first-line therapy in postmenopausal women with advanced breast cancer. It is also indicated for the hormonal treatment of advanced/metastatic breast cancer in women with natural or artificially-induced postmenopausal status, who have disease progression following antiestrogen therapy.
Femara* (letrozole) is also indicated for use in the extended adjuvant treatment of hormone receptor-positive early breast cancer in postmenopausal women who have received approximately 5 years of prior standard adjuvant tamoxifen therapy.
Contraindications
Femara* (letrozole) is contraindicated in premenopausal endocrine status, pregnancy, and lactation.
Femara* (letrozole) is contraindicated in women with premenopausal endocrine status, in pregnancy, and/or lactation due to the potential for maternal and fetal toxicity and fetal malformations.
Warnings Reproductive Toxicology
Letrozole was evaluated for maternal toxicity as well as embryotoxic, fetotoxic and teratogenic potential in female rats following oral administration of daily doses of 0.003, 0.01 or 0.03 mg/kg on gestation days 6 through 17. Oral administration of letrozole to pregnant rats resulted in teratogenicity and maternal toxicity at 0.03 mg/kg. Embryotoxicity and fetotoxicity were seen at doses = 0.003 mg/kg and there was an increase in the incidence of fetal malformation among the animals treated. However it is not known whether this was an indirect consequence of the pharmacological activity of Femara* (inhibition of estrogen biosynthesis) or a direct drug effect.
Novartis recommends the use of Femara* within the labeled indications.
* Femara is a registered trademark.
SOURCE: Novartis Pharmaceuticals Canada Inc.
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