Anastrozole is an oral aromatase inhibitor available as a 1 mg pill. It belongs to the class of medications used in women's health and oncology support, primarily to reduce estrogen production in post-menopausal women with hormone-responsive breast cancer. In Hong Kong, anastrozole is a prescription-only medicine regulated by the Department of Health’s Drug Office. Commercially, the same active ingredient is marketed under brand names such as Arimidex.
Anastrozole blocks the enzyme aromatase, which converts androgens (e.g., testosterone) into estrogen. By inhibiting this enzyme, anastrozole markedly lowers circulating estrogen levels.
These indications are based on large clinical trials that demonstrated improved disease-free survival when anastrozole is used as part of adjuvant therapy.
Off-label use requires medical supervision and individualized risk assessment.
Absolute contraindications
Relative contraindications
Special populations
These effects are usually mild and may lessen with continued therapy.
This article provides educational information about anastrozole and is not a substitute for professional medical advice. Treatment decisions, including use for unapproved indications, must be made under the guidance of a qualified healthcare provider. The content is intended for informational purposes and does not constitute medical recommendations. Always consult a physician before starting, stopping, or changing any medication regimen.
Current evidence does not support routine use of anastrozole for primary prevention of breast cancer in women without a known diagnosis. Clinical guidelines reserve aromatase inhibitors for treatment after a cancer diagnosis, and any preventive use would be off-label and require specialist oversight.
Anastrozole lowers estrogen, a hormone that helps maintain bone density. Patients are advised to undergo baseline BMD testing, supplement calcium and vitamin D, and consider bisphosphonate therapy if significant bone loss occurs.
Concurrent use is generally contraindicated because anastrozole suppresses estrogen, directly opposing HRT. If estrogen levels need to be reduced, clinicians will typically discontinue HRT before starting anastrozole.
Both drugs inhibit aromatase, but anastrozole is taken at 1 mg daily, whereas letrozole is typically dosed at 2.5 mg daily. Pharmacokinetic profiles, side-effect spectra, and physician preferences may vary; selection depends on individual patient factors and treatment guidelines.
Soy products contain phytoestrogens that may partially counteract anastrozole’s estrogen-lowering effect. Patients should discuss supplement use with their oncologist to avoid potential interference with therapy.
Anastrozole is a prescription-only medication in Hong Kong and most other jurisdictions. Carry a copy of the prescription and the original pharmacy label when traveling; some countries may require a local prescription for refills.
Weight changes are not a common direct effect of anastrozole. However, menopausal symptoms such as hot flashes or fatigue may indirectly influence activity levels and appetite.
Because anastrozole is metabolised hepatically, severe liver impairment may increase drug exposure. Dose adjustment is often considered on a case-by-case basis, and liver function tests should be monitored.
Take the missed tablet as soon as you remember, provided it is still the same day. If it is already near the time for the next scheduled dose, skip the missed tablet and continue with the regular dosing schedule. Do not double the dose.
Adjuvant therapy often lasts five years, but duration may be individualized based on tumor characteristics, response, and tolerability. Your oncologist will determine the optimal treatment length for your situation.
