Anastrozole prevents the conversion of adrenal androgens (e.g. testosterone) to estrogen in peripheral and tumour tissues. As the growth of many breast cancers is stimulated and/or maintained by the presence of estrogen, anastrozole helps to treat these cancers by decreasing the levels of circulating estrogens. Anastrozole has a relatively long duration of action allowing for once daily dosing – serum estradiol is reduced by approximately 70% within 24 hours of beginning therapy with 1mg once daily, and levels remain suppressed for up to 6 days following cessation of therapy.
The incidence of ischemic cardiovascular events was increased during anastrozole therapy and patients with pre-existing ischemic heart disease should consider the risks and benefits of anastrozole before beginning therapy. Anastrozole has also been reported to decrease spine and hip bone mineral density (BMD), so consideration should be given to monitoring of BMD in patients receiving long-term therapy.
Anastrozole side effects
Get emergency medical help if you have signs of an allergic reaction (hives, difficult breathing, swelling in your face or throat) or a severe skin reaction (fever, sore throat, burning eyes, skin pain, red or purple skin rash with blistering and peeling).
Anastrozole may decrease blood flow to your heart, especially if you have ever had coronary artery disease (clogged arteries). Seek medical attention if you have new or worsening chest pain, or if you feel short of breath.
Call your doctor at once if you have:
- shortness of breath (even with mild exertion), swelling, rapid weight gain;
- numbness, prickly feeling, pain, or weakness in your hands or wrists;
- symptoms of bone fracture–bruising, swelling, tenderness, pain that worsens with movement;
- liver problems–right-sided upper stomach pain, yellowing of your skin or eyes, and not feeling well; or
- signs of a stroke–sudden numbness or weakness (especially on one side of the body), sudden severe headache, slurred speech, problems with vision or balance.
Common side effects may include:
- numbness, tingling, or tickling feeling in your skin;
- hot flashes;
- joint pain or stiffness;
- bone pain, risk of fracture;
- swelling in your arms, legs, or feet;
- sore throat, cough, shortness of breath;
- headache, back pain;
- depression, sleep problems (insomnia);
- high blood pressure;
- nausea, vomiting; or
Incidence Not Known
- Blistering, peeling, or loosening of the skin
- dark urine
- difficulty swallowing
- dry mouth
- general tiredness and weakness
- hives or welts, itching, skin rash
- incoherent speech
- increased urination
- joint or muscle pain
- large, hive-like swelling on the face, eyelids, lips, tongue, throat, hands, legs, feet, or genitals
- light-colored stools
- loss of appetite
- metallic taste
- muscle weakness
- puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
- red skin lesions, often with a purple center
- red, irritated eyes
- sores, ulcers, or white spots in the mouth or on the lips
- stomach pain
- upper right abdominal pain
- weight loss
- yellow eyes and skin
Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:
Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.
It is very important that your doctor check your progress at regular visits to make sure that this medicine is working properly. Blood tests may be needed to check for unwanted effects.
It is unlikely that a postmenopausal woman may become pregnant. But, you should know that using this medicine while you are pregnant could harm your unborn baby. Use an effective form of birth control during treatment with this medicine and for at least 3 weeks after the last dose. If you think you have become pregnant while using this medicine, tell your doctor right away.
Do not use this medicine together with tamoxifen (Nolvadex®, Soltamox®).
This medicine may cause serious allergic reactions, including anaphylaxis and angioedema, which can be life-threatening and require immediate medical attention. Call your doctor right away if you have itching, hives, hoarseness, trouble breathing or swallowing, or any swelling of your hands, face, or mouth while you are using this medicine.
Check with your doctor right away if you start having chest pains or difficulty with breathing. This medicine may increase the chance of heart problems, including heart attack, in women who have a history of ischemic heart disease.
This medicine may decrease bone mineral density when used for a long time. A low bone mineral density can cause weak bones or osteoporosis. If you have any questions about this, talk to your doctor.
This medicine may increase your cholesterol or fat in the blood. If this happens, your doctor may give you medicine to lower the cholesterol and fat.
Do not take other medicines unless they have been discussed with your doctor. This includes prescription or nonprescription (over-the-counter [OTC]) medicines for appetite control, asthma, colds, cough, hay fever, or sinus problems, and herbal or vitamin supplements.