<b>Letrozole   [Femara] </b>

<b>Sold as :</b> Femara, film-coated 2.5 mg tablet. Manufactured by Novartis. It is essential that the package insert be consulted for detailed information on the usual cautions, precautions, and contraindications. 
This drug is approved by the FDA for treatment of cancer in postmenopausal women. It is currently being used for second-line treatment of postmenopausal women with advanced breast cancer who failed Tamoxifen. 

<b>Dosage and Route of Administration</b>
Femara is taken orally with or without food, and is rapidly and completely absorbed, with uptake in peripheral tissues and minimal binding to plasma proteins. It is metabolized to inactive products in the liver by the cytochrome P450 system. The drug and its metabolites are excreted by the kidneys. The usual dose is 2.5 mg PO q day until disease progression. No dosage adjustment is required for geriatric patients, for patients with creatinine clearances of at least 10mL/minute, or patients with moderate hepatic impairment. No studies have been done on use of Femara in patients with severe liver impairment: caution is advised. When liver function is impaired, monitor liver function at baseline and periodically during therapy. Mild elevation in serum transaminases and serum bilirubin are seen most often in patients with established metastatic disease in the liver. 

<b>Indicatons for Use</b>
Letrozole is indicated only for post-menopausal women. Letrozole use in pre-menopausal women has not been studied, and might increase the risk of benign ovarian tumors and cystic ovarian disease in that population. Letrozole selectively inhibits the conversion of androgens to estrogens, and does not affect synthesis of adrenal corticosteroid, aldosterone, or thyroid hormone. 

<b>How it works:</b>
It is a hormonal agent, a non-steroidal aromatase inhibitor, preventing the production of estrogen. It inhibits synthesis of estrogens by inhibiting the conversion of adrenal androgens (androstenedione and testosterone) to estrogens (estrone, estrone sulfate, and estradiol). Within 2 weeks, serum estradiol levels are suppressed by 90%, by 6 weeks of therapy; estradiol levels are suppressed by 97%. 
Because estrogen acts as a growth factor for hormone-dependent breast cancer cells, reduction of estrogen levels inhibits tumor growth as well as delaying progression of disease. In post-menopausal women, ovarian secretion of estrogen declines and conversion of adrenal androgens (mainly androstenedione and testosterone) to estrone and estradiol in peripheral tissues (adipose, muscle, and liver), catalyzed by the aromatase enzyme, is the principal source of estrogens. Letrozole inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P-450 unit of the enzyme. Inhibition of estrogen synthesis reduces concentrations of circulating estrogens, including estrone, estradiol, and estrone sulfate.

<b>SIDE EFFECTS:</b> 
This drug is generally well tolerated. Fatigue, nausea, constipation, diarrhea, headache, drowsiness or dizziness may occur. If these persist or worsen, notify your doctor promptly. Report promptly any chest pain, stomach pain, trouble breathing, hot flushes, rash or itching. Report promptly any swelling, redness, weakness or pain in legs or arms, vision problems or unusual vaginal bleeding. If you notice other effects not listed above, contact your doctor or pharmacist. Mild bone, muscle and joint pains are the most common side effects. Headache and fatigue can occur as can mild nausea with less frequent vomiting and anorexia. Hot flashes occur in about 6% of patients. Thromboembolic events are rare, and less common than with megestrol acetate. Limit alcohol intake as it may increase the side effects of this drug. Caution performing tasks requiring mental alertness (e.g., driving), since it is possible this drug may cause drowsiness. This drug is not recommended for use during pregnancy. It is not known if this drug is excreted into breast milk. Consult your doctor before breast-feeding. 

Before taking this drug, notify your doctor of any of the following: If you are pregnant, breast-feeding or planning children in the future, inform your doctor. This drug may cause birth defects if either the male or female is taking it at the time of conception or during pregnancy. Men and women who are taking this drug need to use some kind of birth control. However, do not use oral contraceptives ("the pill") without checking with your doctor. Tell your doctor of all nonprescription and prescription medication you may use, especially drugs that may cause drowsiness such as sedatives, tranquilizers, psychiatric medications, certain cough-and-cold products containing antihistamines (e.g., diphenhydramine), anti-seizure drugs, muscle relaxants and narcotic pain relievers (e.g., codeine). Do not start or stop any medicine without doctor or pharmacist approval, including vitamins and herbals. If you have any of the following medical problems:chickenpox or exposure to chickenpox, gout, heart disease, congestive heart failure, shingles, kidney stones, liver disease. If you miss a dose, use it as soon as you remember. If it is near the time of the next dose, skip the missed dose and resume your usual dosing schedule. Do not "double-up" the dose to catch up. Store at room temperature, away from light and moisture. 

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