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Information |
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Drug Groups
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approved; investigational |
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Description
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Anastrozole is a drug indicated in the treatment of breast cancer in post-menopausal women. It is used both in adjuvant therapy (i.e. following surgery) and in metastatic breast cancer. It decreases the amount of estrogens that the body makes. Anastrozole belongs in the class of drugs known as aromatase inhibitors. It inhibits the enzyme aromatase, which is responsible for converting androgens (produced by women in the adrenal glands) to estrogens. |
| Indication |
For adjuvant treatment of hormone receptor positive breast cancer , as well as hormonal treatment of advanced breast cancer in post-menopausal women. Has also been used to treat pubertal gynecomastia and McCune-Albright syndrome; however, manufacturer states that efficacy for these indications have not been established. |
| Pharmacology |
Anastrozole is a potent and selective non-steroidal aromatase inhibitor indicated for the treatment of advanced breast cancer in post-menopausal women with disease progression following tamoxifen therapy. Many breast cancers have estrogen receptors and growth of these tumors can be stimulated by estrogens. In post-menopausal women, the principal source of circulating estrogen (primarily estradiol) is conversion of adrenally-generated androstenedione to estrone by aromatase in peripheral tissues, such as adipose tissue, with further conversion of estrone to estradiol. Many breast cancers also contain aromatase; the importance of tumor-generated estrogens is uncertain. Treatment of breast cancer has included efforts to decrease estrogen levels by ovariectomy premenopausally and by use of anti-estrogens and progestational agents both pre- and post-menopausally, and these interventions lead to decreased tumor mass or delayed progression of tumor growth in some women. Anastrozole is a potent and selective non-steroidal aromatase inhibitor. It significantly lowers serum estradiol concentrations and has no detectable effect on formation of adrenal corticosteroids or aldosterone. |
| Toxicity |
In rats, lethality is greater than 100 mg/kg. |
| Affected Organisms |
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Humans and other mammals |
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| Biotransformation |
Hepatic. Metabolized mainly by N-dealkylation, hydroxylation, and glucuronidation to inactive metabolites. Primary metabolite is an inactive triazole. |
| Absorption |
Rapidly absorbed into the systemic cirulation following oral administration. Peak plasma concentrations are usually attained within 2 hours under fasting conditions, with steady-state plasma concentrations attained in approximately 7 days. |
| Half Life |
50 hours |
| Protein Binding |
40% |
| Elimination |
Hepatic metabolism accounts for approximately 85% of anastrozole elimination. Renal elimination accounts for approximately 10% of total clearance. |
| References |
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Howell A, Cuzick J, Baum M, Buzdar A, Dowsett M, Forbes JF, Hoctin-Boes G, Houghton J, Locker GY, Tobias JS: Results of the ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial after completion of 5 years' adjuvant treatment for breast cancer. Lancet. 2005 Jan 1-7;365(9453):60-2.
[Pubmed]
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Mauras N, Bishop K, Merinbaum D, Emeribe U, Agbo F, Lowe E: Pharmacokinetics and pharmacodynamics of anastrozole in pubertal boys with recent-onset gynecomastia. J Clin Endocrinol Metab. 2009 Aug;94(8):2975-8. Epub 2009 May 26.
[Pubmed]
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Nabholtz JM: Role of anastrozole across the breast cancer continuum: from advanced to early disease and prevention. Oncology. 2006;70(1):1-12. Epub 2006 Jan 26.
[Pubmed]
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Milani M, Jha G, Potter DA: Anastrozole Use in Early Stage Breast Cancer of Post-Menopausal Women. Clin Med Ther. 2009 Mar 31;1:141-156.
[Pubmed]
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Gangadhara S, Bertelli G: Long-term efficacy and safety of anastrozole for adjuvant treatment of early breast cancer in postmenopausal women. Ther Clin Risk Manag. 2009 Aug;5(4):291-300. Epub 2009 May 4.
[Pubmed]
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Santen RJ, Brodie H, Simpson ER, Siiteri PK, Brodie A: History of aromatase: saga of an important biological mediator and therapeutic target. Endocr Rev. 2009 Jun;30(4):343-75. Epub 2009 Apr 23.
[Pubmed]
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