Breast Cancer Drug Not for Fertility
Femara May Cause Birth Defects; Risk Already Noted on Product
Nov. 30, 2005 -- The drug company Novartis is warning women not to take its drug Femara to boost fertility because of the potential risk of birth defects.
The drug company's Canadian branch is sending letters to Canadian fertility specialists about the risk, which isn't new and is noted on Femara's product information.
"A similar letter is expected to go out by the end of this week in the U.S.," says Kim Fox, director of global public relations for Novartis Oncology. Letters will be also sent in other countries, Fox tells WebMD.
Not Approved for Fertility Use
Femara isn't intended for use in fertility treatments. It's only approved for use by postmenopausal women with breast cancer.
Femara's labeling warns women not to take the drug if they are pregnant, might become pregnant, or are breastfeeding.
Femara is an aromatase inhibitor. It curbs production of estrogen, a female sex hormone which fuels some (but not all) breast cancers.
Fox says Novartis doesn't know how commonly Femara has been used for fertility. She says the company's worldwide safety database has records of 13 patients who have used the drug for that unapproved purpose -- known as "off-label" use.
The database just notes those patients' off-label use of Femara, not the outcome of any pregnancies they may have had.
Novartis' letter to Canadian fertility doctors appears on the web site of Health Canada, the Canadian health agency.
The letter came after Canadian researchers presented findings on Femara's off-label fertility use. The study by Marinko Biljan, MD, MRCOG, and colleagues was presented on Oct. 18 in Montreal at the annual meeting of the American Society of Reproductive Medicine.
Tracking Birth Defects
The study included 150 babies born to women who had taken Femara for fertility. The women had been treated at the Montreal Fertility Centre, where Biljan works. Some had only taken Femara; others had taken Femara along with other hormonal drugs.
Overall, there were no differences in birth defects between the two groups treated with the drugs, write the researchers. But compared with babies born to women who did not use the drugs, those born to Femara users had significantly higher rates of locomotor malformations and heart abnormalities and lower birth weights.