Pharmacokinetics and Indications: Letrozole is a selective aromatase inhibitor. As Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme. Estrogens then bind to an estrogen receptor, which causes cells to divide. Letrozole prevents the aromatase from producing estrogens by competitive, reversible binding to the heme of its cytochrome P450unit. Letrozole 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.
Possible Side Effects: The use of Letrozole may cause decreases in the density of your bones, increases in bone fractures and osteoporosis. Monitoring of the density of your bones may be required. Some people taking Letrozole had an increase in cholesterol. Your doctor may require the monitoring of cholesterol in your blood. Some reported fatigue, dizziness and drowsiness with Letrozole. Until you know how it affects you, use caution before driving or operating machinery. Some people had moderate, temporary decreases in white blood cell counts. The medical significance of this is not known. The most serious side effects seen with Letrozole are bone effects (fractures, decreased bone density and osteoporosis) and increases in cholesterol. Other common side effects seen with Letrozole include joint pain, nausea, weight decrease and pain in the extremities. Other important less commonly reported side effects include blood clots, other cancers, stroke, heart attack and endometrial cancer.
Effective Dose : 1.25 - 2.5 mg / day or every other day
Use for : Cycle Period