<b>Anastrozole (ann-uh-STROW-zole) [Arimidex]</b>

<b>Sold as:</b> Arimidex, film-coated tablets, 1 mg, manufactured by AstraZeneca It is essential that the package insert be consulted for detailed information on the usual cautions, precautions, and contraindications. 
 
<b>Indications for use:</b>
Anastrozole is used for the first-line treatment of hormone receptor-positive or hormone receptor-unknown locally advanced or metastatic breast cancer in postmenopausal women. Data from 2 double-blind, randomized clinical trials in such patients indicate that anastrozole is at least as effective as tamoxifen for producing objective tumor response and delaying tumor progression. Anastrozole is also used for the second-line treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. Anastrozole therapy generally is continued until tumor progression is evident. 

<b>How it works:</b>
It is a hormonal agent, a potent and selective 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%. Anastrozole selectively inhibits the conversion of androgens to estrogens, and does not affect synthesis of adrenal corticosteroid, aldosterone, or thyroid hormone. 

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 to estrogens in peripheral tissues (adipose, muscle, and liver), catalyzed by the aromatase enzyme, is the principal source of estrogens. Anastrozole 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. Anastrozole does not affect synthesis of adrenal corticosteroid, aldosterone, or thyroid hormone. 

<b>Dose and Route of Administration</b>
The usual dosage of anastrozole is 1 mg daily, and it is taken orally with or without food, and is rapidly and completely absorbed, with wide distribution. About 40% of drug binds to plasma proteins. It is extensively metabolized in the liver to inactive forms. Half-life of the drug is approximately 50 hours and steady-state levels are achieved after 7 days. The major route of elimination is fecal with renal clearance accounting for only 10% of excretion. No dose adjustments are required for geriatric patients or patients with either hepatic or renal dysfunction. No studies have been done on use of anastrozole in patients with severe liver impairment: caution is advised, when liver function is impaired, monitor liver function at baseline and periodically during therapy. 

Warning: Do not use if you are pregnant, plan to become pregnant or while breastfeeding. 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 during therapy and for one month following. However, do not use oral contraceptives ("the pill") without checking with your doctor. 

<b>SIDE EFFECTS:</b>
 Diarrhea, constipation, nausea, vomiting, loss of appetite (16 to 20%), headache, hot flashes, dizziness, dry mouth, back pain, vaginal dryness and cough may occur. Changes in diet such as eating several small meals or limited activity may help lessen nausea and vomiting. In some cases, therapy with another drug may be necessary to prevent or relieve nausea. Hot flashes occur in 10% of patients. A flu-like syndrome of fever, malaise, muscle and joint pains may occur, as may a dry, scaling skin rash. Blood pressure and white cell count should be monitored. There might occur thrombophlebitis and/or thromboembolism. Hair loss, breast pain, vaginal dryness, weight gain, and rhinitis/sinusitis can occur. 

Notify your doctor if you experience: breathing trouble, rash, vaginal bleeding, shortness of breath, chest pain, pain or swelling in the legs, swelling of the feet or ankles (peripheral edema occurs in 7% of patients), weight gain, tingling of the hands or feet, depression. If you notice other effects not listed above, contact your doctor or pharmacist. 

Before taking this drug, notify your doctor of any of the following: 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. Tell your doctor of any nonprescription or prescription medication, or herbal or other supplement you may take. Do not start or stop any medicine without doctor or pharmacist approval. Never begin taking a new medication, prescription or nonprescription, without asking your doctor or nurse if it will interact with alcohol, foods or other medications. If you miss a dose, take 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, andaway from heat and moisture. Keep this and all medications out of the reach of children. 

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