Aromatase Inhibitors (AI's)

Aromatase inhibitors (AI’s) work by inhibiting the action of the enzyme aromatase, which converts androgens into estrogens by a process called aromatization.

Aromatase inhibitors (AI’s) are a class of drugs used in the treatment of breast cancer in postmenopausal women and in men, and gynecomastia in men. They may also be used off-label to reduce estrogen conversion when supplementing testosterone exogenously.

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, AI’s are estrogen synthesis inhibitors. AI’s are taken to either block the production of estrogen or block the action of estrogen on receptors.