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What is Anastrozole?

Feb 11，2020

Anastrozole, a third-generation nonsteroidal aromatase inhibitor, is effective in postmenopausal women with estrogen receptor-positive metastatic breast cancer. In addition, it has also been reported effective as adjuvant hormonal therapy for these women.[1]

Anastrozole is a benzyltriazole derivative that reduces estrogen synthesis by binding competitively to the haem group of the cytochrome P450 unit of aromatase. It is a potent, selective aromatase inhibitor and has minimal or no effects on adrenal steroid hormones. In healthy postmenopausal women, multiple doses of anastrozole 1 mg/day led to prolonged suppression of plasma estradiol by >80% from baseline levels. In postmenopausal women with advanced breast cancer, plasma and tumour tissue estradiol levels were reduced from baseline levels by ≈90%. In a large clinical trial, after 12 and 24 months of follow-up, anastrozole was associated with decreased hip and lumbar spine bone mineral density, and an increase in serum cholesterol levels. In contrast with tamoxifen, after 5 years’ treatment there was no increase in endometrial thickening with anastrozole. [2]

Anastrozole has linear pharmacokinetics. It is metabolized primarily in the liver, with a plasma elimination half-life of 40–50 hours, indicating that oncedaily administration is adequate. In vitro and clinical studies indicate that drugdrug interactions are unlikely to occur between anastrozole and drugs metabolized by hepatic cytochrome P450 enzymes. In patients with breast cancer, there were no clinically important interactions between anastrozole and tamoxifen or its metabolite, N-desmethyltamoxifen. [3]

Anastrozole is a generally well tolerated treatment for early-stage breast cancer. Like other aromatase inhibitors, its most important adverse effect was an increased risk of bone fractures, which for anastrozole was restricted to the treatment period. It characteristically has mild toxicity when compared with chemotherapy; however, it have been noticed that more patients treated with anastrozole have complained of joint symptoms than expected, particularly digital stiffness similar to that of rheumatoid arthritis. Some clinical trials of anastrozole for postmenopausal women with breast cancer in Europe and the United states reported musculoskeletal disorders as adverse events. [4]

In all, Anastrozole (Arimidex®) is an aromatase inhibitor approved in the EU, the US and in other countries worldwide for use as an adjuvant treatment in postmenopausal women with early-stage, hormone receptor-positive breast cancer. It is also approved in the EU and other countries worldwide for continuing adjuvant treatment in women who have already had 2–3 years of adjuvant tamoxifen treatment for breast cancer.

References

1.Buzdar A, Howell A. Advances in aromatase inhibition: clinical efficacy and tolerability in the treatment of breast cancer[J]. Clin Cancer Res. 2001, 7: 2620-35

2.Tsangaris T, Robert N, Love N. Update on treatment of early breast cancer: the trend toward less surgery, more systemic therapy[J]. Postgrad Med, 1999, 15(105): 81-102

3.Buzdar A. The place of chemotherapy in the treatment of early breast cancer[J]. Br J Cancer 1998,78(Suppl. 4): 16-20

Wiseman LR, Adkins JC. Anastrozole: a review of its use in the management of postmenopausal women with advanced breast cancer[J]. Drugs Aging, 1998, 13 (4): 321-32