Why is this drug prescribed?

Arimidex tablets contain the active ingredient anastrozole, which is a type of drug known as a non-steroidal aromatase inhibitor. It works by preventing the action of an enzyme in the body called the aromatase enzyme. The aromatase enzyme is involved in the production of the female sex hormone, oestrogen. In women who have passed the menopause, oestrogen is mainly produced by this enzyme. In postmenopausal women the aromatase enzyme converts the sex hormones androstenedione, and testosterone, into oestrogen. Anastrozole prevents this conversion by blocking the action of the aromatase enzyme. This causes oestrogen levels in the body to fall. Many breast cancers are sensitive to oestrogen, and they need this hormone to grow. These types of breast cancer are termed 'hormone receptor positive'. Oestrogen binds to oestrogen receptors on the breast cancer cells and causes changes within the cells that result in faster growth of the cancer. By lowering the levels of oestrogen in the body, anastrozole effectively starves the breast cancer cells, thus helping to stop them grow. Anastrazole helps prevent breast cancer from spreading to other areas of the body and also reduces risk of developing cancer in the other breast. Anastrazole is only effective in postmenopausal women, since before the menopause oestrogen is mainly produced by the ovaries and not by the aromatase enzyme.

Treatments

* Advanced breast cancer in women who have passed the menopause * Treating postmenopausal women who have had surgery to remove early hormone receptor positive breast cancer. It can either be used for five years immediately following the surgery, or after two to three years of taking tamoxifen.

What side effects can this drug cause?

* Hot flushes * Weakness or loss of strength * Joint pain or stiffness * Mood disturbances * Vaginal dryness * Hair thinning * Rash * Headache * Diarrhoea * Nausea and vomiting * Loss of appetite * Vaginal bleeding * Sleepiness * Raised cholesterol levels * Decreased bone density * Very rare severe skin reactions