Arimidex (generic: Anastrozole) is a prescription medication used to treat breast cancer. It belongs to a class of medications called aromatase inhibitors that work by reducing the amount of estrogen produced in the body. Arimidex 1mg comes in a tablet form and is typically taken once a day. The recommended dose is one tablet (1mg) taken orally once a day or as prescribed by your doctor. Arimidex 1mg comes in 50 tablets per package.