Exeplex

Exemestane (Exeplex) is an oral steroidal aromatase inhibitor (but also known uniquely as an aromatase inactivator) used in the adjuvant treatment of hormonally-responsive (also called hormone-receptor-positive, estrogen-responsive) breast cancer in postmenopausal women. The aim of Exeplex is to lower estrogen levels.

Exemestane is an irreversible, steroidal aromatase inactivator, structurally related to the natural substrate androstenedione. It acts as a false substrate for the aromatase enzyme, and is processed to an intermediate that binds irreversibly to the active site of the enzyme causing its inactivation, an effect also known as "suicide inhibition." In other words, the Exemestane, by being structurally similar to the target of the enzymes, permanently binds to those enzymes, thereby preventing them from ever completing their task of converting androgens into estrogen.

The estrogen suppression rate for exemestane varies from 85% to 95%.