Anastrozole

Mechanism of Action
Anastrozole is a selective nonsteroidal aromatase inhibitor. Many breast cancers have estrogen receptors; the growth of these tumors is stimulated by estrogen. In postmenopausal women, the main source of estrogen is the conversion of adrenal androgen to estrogen (primarily estradiol) by aro-matase in the peripheral tissues, such as the adipose tissue.

Indications
Treatment of advanced breast cancer in postmenopausal women whose disease has progressed after tamoxifen therapy.

Metabolism/Excretion
Metabolized by the hepatic system and excreted in the urine. Half-life: 7 days.

Dosage Range
Adult: For breast cancer, 1 mg/day.
Pediatric: Safety and efficacy not established.

Drug Preparation/Stability
Available in 1-mg tablets.

Drug Administration
PO

Drug Interaction
None known

Side Effects and Toxicities
¨ Cardiac: Chest pain, peripheral edema
¨ CNS: Dizziness, depression, headache
¨ Cutaneous: Rash
¨ GI: Vomiting, diarrhea, constipation, abdominal pain, anorexia, dry mouth
¨ Other: Bone pain, pharyngitis, increased cough, pelvic pain

Special Considerations
Replacement therapy with glucocorticoids or mineralocorti-coids is not necessary with anastrozole because it does not affect cortisol or aldosterone secretion.