ARIMIDEX (anastrozole) tablets for oral administration contain 1 mg of anastrozole, a non-steroidal aromatase inhibitor. It is chemically described as 1,3-Benzenediacetonitrile, a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1-ylmethyl). Its molecular formula is C₁₇H₁₉N₅ and its structural formula is:

Anastrozole is an off-white powder with a molecular weight of 293.4. Anastrozole has moderate aqueous solubility (0.5 mg/mL at 25°C); solubility is independent of pH in the physiological range. Anastrozole is freely soluble in methanol, acetone, ethanol, and tetrahydrofuran, and very soluble in acetonitrile.

Each tablet contains as inactive ingredients: lactose, magnesium stearate, hydroxypropylmethylcellulose, polyethylene glycol, povidone, sodium starch glycolate, and titanium dioxide.

SIDE EFFECTS: Constipation, diarrhea, nausea, vomiting, upset stomach, loss of appetite, body aches and pains, breast swelling/tenderness/pain, headache, dry mouth, scratchy throat, increased cough, dizziness, trouble sleeping, tiredness/weakness, flushing and sweating (hot flashes/hot flushes), vaginal bleeding, hair thinning, and weight change can occur. Changes in diet such as eating several small meals may help lessen the chance of nausea and vomiting. If any of these effects persist or worsen, notify your doctor or pharmacist promptly.

Remember that your doctor has prescribed this medication because he or she has judged that the benefit to you is greater than the risk of side effects. Many people using this medication do not have serious side effects.

Tell your doctor immediately if any of these unlikely but serious side effects occur: mental/mood changes (e.g., depression), numbness/tingling/swelling of the hands or feet, persistent cough, unusual vaginal discharge/burning/itching/odor, unusually stiff muscles, pain/redness/swelling of the arms or legs, vision changes, bone pain, bone fracture, signs of infection (e.g., fever, chills, persistent sore throat).

Seek immediate medical attention if any of these rare but very serious side effects occur: chest pain, jaw/left arm pain, trouble breathing, confusion, fainting, slurred speech, weakness on one side of the body.

A very serious allergic reaction to this drug is unlikely, but seek immediate medical attention if it occurs. Symptoms of a serious allergic reaction may include: rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.

This is not a complete list of possible side effects. If you notice other effects not listed above, contact your doctor or pharmacist.

In the US -

Call your doctor for medical advice about side effects. You may report side effects to FDA at 1-800-FDA-1088.

In Canada - Call your doctor for medical advice about side effects. You may report side effects to Health Canada at 1-866-234-2345.

PRECAUTIONS: Before taking anastrozole, tell your doctor or pharmacist if you are allergic to it; or if you have any other allergies. This product may contain inactive ingredients, which can cause allergic reactions or other problems. Talk to your pharmacist for more details.

Before using this medication, tell your doctor or pharmacist your medical history, especially of: liver disease, high blood pressure, heart disease (such as ischemic heart disease, history of chest pain), brittle bone disease (osteoporosis), blood clots.

This drug may make you dizzy. Do not drive, use machinery, or do any activity that requires alertness until you are sure you can perform such activities safely. Limit alcoholic beverages.

Anastrozole is used mainly in women after menopause. If you have not gone through menopause and your doctor has prescribed this for you, this medication must not be used during pregnancy. It may cause harm to an unborn baby or miscarriage. If you become pregnant or think you may be pregnant, tell your doctor immediately. Women of childbearing age should use reliable form(s) of contraception (such as latex condoms) during treatment. Products containing estrogen (such as birth control pills) should not be used. Consult your doctor for more details.

It is not known whether this drug passes into breast milk. Because of the potential risk to the infant, breast-feeding while using this drug is not recommended. Consult your doctor before breast-feeding.