Vorozole is an imidazole

Imidazole

Imidazole is an organic compound with the formula C3H4N2. This aromatic heterocyclic is a diazole and is classified as an alkaloid. Imidazole refers to the parent compound, whereas imidazoles are a class of heterocycles with similar ring structure, but varying substituents...

 based competitive inhibitor of the aromatase

Aromatase

Aromatase is an enzyme responsible for a key step in the biosynthesis of estrogens. It is a member of the cytochrome P450 superfamily , which are monooxygenases that catalyze many reactions involved in steroidogenesis. In particular, aromatase is responsible for the aromatization of androgens into...

 enzyme. It underwent clinical testing for evaluation for use as an antineoplastic agent; however it was withdrawn from testing when no difference was detected in the duration of median survival as compared to the progestational agent megestrol acetate and research instead focused on the other third generation aromatase inhibitors anastrozole

Anastrozole

Anastrozole is an aromatase-inhibiting drug approved for treatment of breast cancer after surgery, as well as for metastasis in both pre and post-menopausal women. The severity of breast cancer is increased by estrogen, as sex hormones cause hyperplasia, and differentiation at estrogen receptor...

, letrozole

Letrozole

Letrozole is an oral non-steroidal aromatase inhibitor for the treatment of hormonally-responsive breast cancer after surgery.Estrogens are produced by the conversion of androgens through the activity of the aromatase enzyme...

 and exemestane

Exemestane

Exemestane is a drug used to treat breast cancer. It is a member of the class of drugs known as aromatase inhibitors. Some breast cancers require estrogen to grow. Those cancers have estrogen receptors , and are called ER-positive. They may also be called estrogen-responsive,...

.

It is selective.

Chemistry

Prous, J.; Grant, J.; Castaner, J.; Drugs Future 1994, 457.