Detailed definition
Aromatase inhibitors (AIs) block the cytochrome P450 enzyme aromatase (CYP19A1), which catalyzes the conversion of androgens to estrogens. Three drugs are in clinical use: anastrozole (Arimidex) and letrozole (Femara) are non-steroidal reversible inhibitors; exemestane (Aromasin) is a steroidal irreversible inhibitor. AIs reduce postmenopausal serum estradiol by >90%, producing a more profound estrogen-deprived state than menopause alone. They are first-line adjuvant therapy for hormone-receptor-positive breast cancer in postmenopausal women, typically used for 5–10 years. Side effects include severe vasomotor symptoms, GSM, accelerated bone loss (women on AIs often need bone-protective therapy), arthralgias, and sexual dysfunction. AIs are not effective in premenopausal women without ovarian suppression because ovarian aromatase produces enough estrogen to overcome inhibition.
Why it matters in menopause
Women on AIs are among the most symptomatic populations in menopause care. Vaginal estrogen at low doses is permitted by some oncologists for severe GSM, though the data are limited. Fezolinetant, vaginal DHEA (prasterone), ospemifene, and non-hormonal vasomotor treatments are particularly relevant for AI patients. Bone monitoring is essential.
Related terms
Sources
External references: Wikipedia.