Drug safety evaluation of exemestane.

INTRODUCTION: Hormone-dependent breast cancer can be successfully treated by either blocking the estrogen receptor, as with tamoxifen, or reducing the production of estrogens, as with aromatase inhibitors. Exemestane is a third-generation aromatase inhibitor used in the treatment of estrogen-receptor-positive breast cancer in postmenopausal women. In various trials, exemestane has shown superiority over tamoxifen in both efficacy and safety. Furthermore, aromatase inhibitors are gaining territory in the metastatic, as well as the early, setting for treating patients with breast cancer. AREAS COVERED: The authors describe the mechanism of action and pharmacokinetic/pharmacodynamic characteristics of exemestane and discuss its efficacy and safety within the framework of currently approved and potential new indications. The reader can expect a full update on the characteristics of exemestane, including its efficacy and safety profile compared with tamoxifen and other third-generation aromatase inhibitors. EXPERT OPINION: Exemestane is a safe drug due to its steroidal structure, which blocks aromatase at a different site to nonsteroidal AIs (eg., anastrozole and letrozole). Noncross-resistance with nonsteroidal aromatase inhibitors makes it an attractive alternative for all clinical indications of aromatase inhibitors in patients with breast cancer.