What is letrozole, and how does it work (mechanism of action)?
Letrozole is an oral, anti-estrogen drug that is used for treating postmenopausal women with breast cancer. The growth of some breast cancers in postmenopausal women is promoted by estrogens that circulate in the blood, and the adrenal glands are the main source of these circulating estrogens. Letrozole inhibits the enzyme in the adrenal glands (aromatase) that produces the estrogens, estradiol and estrone. Letrozole was approved by the FDA in 1997.
What brand names are available for letrozole?
Femara
Is letrozole available as a generic drug?
Yes
Do I need a prescription for letrozole?
Yes
What are the side effects of letrozole?
The most common side effects with letrozole are:
- nausea,
- vomiting,
- fatigue,
- headache,
- muscle aches,
- diarrhea,
- constipation, and
- chest pain.
Cholesterol levels may increase during letrozole therapy. Cholesterol levels should be monitored and some patients may require treatment for high cholesterol levels. Letrozole decreases bone mineral density, increasing the risk of osteoporosis and fractures.
SLIDESHOW
Breast Cancer Awareness: Symptoms, Diagnosis, and Treatment See SlideshowWhat is the dosage for letrozole?
The recommended dose is 2.5 mg once daily with or without food. Patients with severe liver impairment should receive 2.5 mg every other day.
Which drugs or supplements interact with letrozole?
Tamoxifen reduces blood levels of letrozole when both drugs are administered together. However, in clinical studies the benefit of letrozole was not reduced when administered immediately after tamoxifen. Letrozole is an anti-estrogen drug. Therefore, estrogen containing products counteract the effect of letrozole.
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Is letrozole safe to take if I'm pregnant or breastfeeding?
Letrozole damages the fetus. It should not be taken by pregnant women.
It is not known if letrozole is secreted into breast milk.
Summary
Letrozole (Femara) is a drug prescribed for the treatment of postmenopausal women with hormone receptive positive early breast cancer or who have been treated with tamoxifen (Nolvadex). Side effects, drug interactions, and pregnancy information should be reviewed prior to taking this medication.
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