Aromatase inhibitor

Aromatase inhibitor
Drug class
Anastrozole, a non steroidal aromatase inhibitor and a widely used drug in the treatment of breast cancer.
Class identifiers
Synonyms	Estrogen synthesis inhibitors; Estrogen synthase inhibitors; Estrogen blockers
Use	Breast cancer, infertility, precocious puberty, medical abortion, gynecomastia, endometriosis, short stature, others
ATC code	L02BG
Biological target	Aromatase
Chemical class	Steroidal; Nonsteroidal
Legal status
In Wikidata

Aromatase inhibitors (AIs) are a class of drugs used in the treatment of breast cancer in postmenopausal women and in men,^[1][2] and gynecomastia in men. They may also be used off-label to reduce estrogen conversion when supplementing testosterone exogenously. They may also be used for chemoprevention in women at high risk for breast cancer.

Aromatase is the enzyme that catalyzes a key aromatization step in the synthesis of estrogen. It converts the enone ring of androgen precursors such as testosterone, to a phenol, completing the synthesis of estrogen. As such, AIs are estrogen synthesis inhibitors. Because hormone-positive breast and ovarian cancers are dependent on estrogen for growth, AIs are taken to either block the production of estrogen or block the action of estrogen on receptors.