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?
Is letrozole available as a generic drug?
Do I need a prescription for letrozole?
What are the side effects of letrozole?
The most common side effects with letrozole are:
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
What 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
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.
Is letrozole safe to take if I’m pregnant or breastfeeding?
Letrozole damages the fetus. It should not be taken by
It is not known if letrozole is secreted into
What else should I know about letrozole?
What preparations of letrozole are available?
How should I keep letrozole stored?
Tablets should be stored at room temperature, 15 C – 30 C (59 F – 86 F).
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Medically Reviewed on 3/14/2019
FDA Prescribing Information