BMA Concise Guide to Medicine & Drugs


Brand name Arimidex

Used in the following combined preparations None


Drug group Anticancer drug

Overdose danger rating Low

Dependence rating Low

Prescription needed Yes

Available as generic No


Anastrazole is a potent non-steroidal inhibitor of the enzyme that manufactures oestradiol (natural oestrogen) in the body. It can reduce production of oestradiol by more than 80 per cent. It works by blocking oestradiol production in the peripheral tissues of the body, rather than in the ovary itself, so it is not suitable for use in premenopausal women where the ovaries are still producing oestrogen. The drug is used in postmenopausal women to treat types of breast cancer in which the tumour cells have oestrogen receptors (known as oestrogen-receptor-positive breast cancer).

Anastrazole is generally well tolerated; adverse effects are mainly gastrointestinal or gynaecological, and are generally similar to menopausal symptoms. If there is any doubt about whether a woman to be treated is postmenopausal, a biochemical test may be performed.


Your drug prescription is tailored for you. Do not alter dosage without checking with your doctor.

How taken/used Tablets.

Frequency and timing of doses Once daily.

Adult dosage range 1mg.

Onset of effect 30 minutes.

Duration of action 24 hours.

Diet advice None.

Storage Keep in original container at room temperature out of the reach of children.

Missed dose Take as soon as you remember. If your next dose is due within 2 hours, take a single dose now and skip the next.

Stopping the drug Do not stop the drug without consulting your doctor. Stopping the drug may lead to worsening of the underlying condition.

Exceeding the dose An occasional unintentional extra dose is unlikely to be a cause for concern. But if you notice any unusual symptoms, or if a large overdose has been taken, notify your doctor.


Anastrazole is usually well tolerated and any side effects tend to be relatively minor, except for the increased risk of osteoporosis and bone fracture. The more common side effects include hot flushes, headache, fatigue, dizziness, joint pain or stiffness, vaginal dryness, thinning of the hair, nausea, and diarrhoea. If any of these are severe, consult your doctor. Rarely, anastrazole may cause a rash; if so, stop taking the drug and consult your doctor immediately.


Tamoxifen and oestrogens oppose the effects of anastrozole.


Be sure to tell your doctor if:

· You are premenopausal.

· You have osteoporosis.

· You have kidney or liver problems.

· You are allergic to anastrozole.

· You are taking other medicines.

Pregnancy Not prescribed in pregnancy.

Breast-feeding Not prescribed when breast-feeding.

Infants and children Not recommended.

Over 60 No special problems.

Driving and hazardous work Do not drive until you know how the drug affects you. It can cause drowsiness.

Alcohol No known problems.


No known problems.

Monitoring Women with osteoporosis or at risk of osteoporosis will have their bone mineral density assessed at the start of treatment and at regular intervals.