Detailed Drug Information:

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.

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 breast cancer that is resistant to the more commonly-used anti-estrogen medications such as tamoxifen (Nolvadex).

DOSING: Letrozole generally is taken once daily, with or without food.

DRUG INTERACTIONS: There are no known drug interactions with 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. The likelihood of side effects is lower than with other drugs used more commonly in patients with breast cancer that is resistant to treatment with anti-estrogens, for example, megestrol (Megace).