letrozole, Femara

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GENERIC NAME: letrozole

BRAND NAME: Femara

DRUG CLASS AND MECHANISM: 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.

GENERIC AVAILABLE: Yes

PRESCRIPTION: Yes

PREPARATIONS: Tablets: 2.5mg.

STORAGE: Tablets should be stored at room temperature, 15-30 C (59-86 F).

PRESCRIBED FOR: Letrozole is used to treat postmenopausal women with hormone receptor positive early breast cancer or who have been treated with tamoxifen (Nolvadex). It also is approved for initial or second-line treatment of postmenopausal women with hormone-sensitive or advanced breast cancer.

DOSING: 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.

DRUG INTERACTIONS: 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.

PREGNANCY: Letrozole damages the fetus. It should not be taken by pregnant women.

NURSING MOTHERS: It is not known if letrozole is secreted into breast milk.

SIDE EFFECTS: 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.

Reference: FDA Prescribing Information


Last Editorial Review: 7/18/2012




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