Information about Letrozole
Letrozole is a nonsteroidal inhibitor of aromatase which effectively blocks estrogen synthesis in postmenopausal women and is used as therapy of estrogen receptor positive breast cancer, usually after resection and after failure of tamoxifen.
Liver safety of Letrozole
Letrozole has been associated with a low rate of serum enzyme elevations during therapy and rare instances of clinically apparent liver injury.
Mechanism of action of Letrozole
Letrozole (let' roe zole) is a nonsteroidal aromatase inhibitor that is widely used as therapy of breast cancer, usually after surgical resection. Aromatase is the enzyme responsible for the conversion of testosterone to estrone (E1) and of androstenedione to estradiol (E2). Highest levels of aromatase are found in the ovary and placenta, which are the major sources of estrogen in premenopausal women. However, aromatase is also found in other tissues, such as liver, kidney, adrenals, brain, muscle and subcutaneous fat where it is also active in producing estrogens, although at low levels. These tissues are the major source of estrogen in postmenopausal women. Inhibitors of aromatase were developed to block the synthesis of estrogen in the peripheral tissues and, thus, as antiestrogen therapy of breast cancer in postmenopausal women. Letrozole is a nonsteroidal, specific aromatase inhibitor which has little or no effect on adrenal glucocorticoid or mineralocorticoid synthesis.
FDA approval information for Letrozole
Letrozole was approved for use in postmenopausal women with estrogen receptor positive breast cancer in the United States in 1997.
Clinical use of Letrozole
Current indications aew as adjuvant therapy in postmenopausal women with estrogen sensitive breast cancer, given in daily oral doses for up to five years. Letrozole is also indicated as a first line treatment of estrogen receptor positive (or unknown), locally advanced or metastatic breast cancer in postmenopausal women.
Brand name for Letrozole
Letrozole is available in 2.5 mg tablets in generic forms and under the brand name Femara.
Dosage and administration for Letrozole
The recommended dose is one tablet of 2.5 mg daily.
Side effects of Letrozole
Common side effects include hot flashes, night sweats, fatigue, dizziness, headache, sleepiness, abdominal discomfort, nausea, arthralgias, weight gain and rash. Uncommon, but potentially severe side effects include decrease in bone mineral density, increases in serum cholesterol levels and embryo-fetal toxicity.