Exemestane is a steroidal suicide aromatase inhibitor, which means that it lowers estrogen production in the body by blocking the aromatase enzyme. Exemestane, the enzyme responsible for estrogen synthesization. averages an 85% rate of estrogen suppression. Exemestane does this by selectively inhibiting aromatase activity in a time-dependent and irreversible manner. 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, 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 estrogens.