Aromatase inhibitors are drugs used to treat breast cancer by blocking the aromatase enzyme; they are typically used in postmenopausal women.
Aromatase converts androgens into estrogen through aromatization. Estrogen stimulates breast tissue, making it more susceptible to cancers, so suppressing the production of estrogen is a way of decreasing the likelihood of breast cancer recurrence.
Typically, aromatase conversion is only a primary source of estrogen in post-menopausal women; pre-menopausal women get most of their estrogen from the ovaries; and the elimination of estrogen, stimulates their bodies to increase androgen production, which counteracts aromatase. For this reason, aromatase inhibitors in pre-menopausal women are useless.
Aromatase inhibitors, or AIs, are categorized as either irreversible steroid inhibitors, which form a permanent bond with armoatase, or non-steroidal inhibitors, which eliminate aromatase uptake by reversible competition. These inhibitors have been shown to be more effective in postmenopausal women than the standard treatment, tamoxifen.
There may be other applications for aromatase inhibitors in the stimulation of ovulation or in treating adolescents with a low predicted adult height; these are under investigation right now.
Web Resources On Aromatase Inhibitor
BreastCancer.org: Aromatase Inhibitors
New Class of Drugs Treats Breast Cancer
Book Resources On Aromatase Inhibitor
Aromatase Inhibitors by William R. Miller et. al.
Anastrozole (Arimidex) Realising the Need for an Oral Selective Aromatase Inhibitor by W. Jonat & M. Kaufmann (Eds)