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2D Structure
Also known as: 120511-73-1, Arimidex, Anastrazole, Anastrozol, Zd1033, 2,2'-(5-((1h-1,2,4-triazol-1-yl)methyl)-1,3-phenylene)bis(2-methylpropanenitrile)
Molecular Formula
C17H19N5
Molecular Weight
293.4  g/mol
InChI Key
YBBLVLTVTVSKRW-UHFFFAOYSA-N
FDA UNII
2Z07MYW1AZ

A nitrile and triazole derivative that acts as a selective nonsteroidal aromatase inhibitor. It is used in the treatment of ESTROGEN NUCLEAR RECEPTOR-positive breast cancer in postmenopausal women.
Anastrozole is an Aromatase Inhibitor. The mechanism of action of anastrozole is as an Aromatase Inhibitor.
1 2D Structure

2D Structure

2 Identification
2.1 Computed Descriptors
2.1.1 IUPAC Name
2-[3-(2-cyanopropan-2-yl)-5-(1,2,4-triazol-1-ylmethyl)phenyl]-2-methylpropanenitrile
2.1.2 InChI
InChI=1S/C17H19N5/c1-16(2,9-18)14-5-13(8-22-12-20-11-21-22)6-15(7-14)17(3,4)10-19/h5-7,11-12H,8H2,1-4H3
2.1.3 InChI Key
YBBLVLTVTVSKRW-UHFFFAOYSA-N
2.1.4 Canonical SMILES
CC(C)(C#N)C1=CC(=CC(=C1)CN2C=NC=N2)C(C)(C)C#N
2.2 Other Identifiers
2.2.1 UNII
2Z07MYW1AZ
2.3 Synonyms
2.3.1 MeSH Synonyms

1. 2,2'-(5-(1h-1,2,4-triazol-1-ylmethyl)-1,3-phenylene)bis(2-methylpropionitrile)

2. Anastrazole

3. Arimidex

4. Ici D1033

5. Zd 1033

6. Zd-1033

7. Zd1033

8. Zeneca Zd 1033

2.3.2 Depositor-Supplied Synonyms

1. 120511-73-1

2. Arimidex

3. Anastrazole

4. Anastrozol

5. Zd1033

6. 2,2'-(5-((1h-1,2,4-triazol-1-yl)methyl)-1,3-phenylene)bis(2-methylpropanenitrile)

7. Ici D1033

8. Zd-1033

9. Ici-d1033

10. 2-[3-(2-cyanopropan-2-yl)-5-(1,2,4-triazol-1-ylmethyl)phenyl]-2-methylpropanenitrile

11. Alpha,alpha,alpha',alpha'-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-m-benzenediacetonitrile

12. Nsc-719344

13. Nsc-759855

14. 2z07myw1az

15. Chembl1399

16. 2,2'-[5-(1h-1,2,4-triazol-1-ylmethyl)benzene-1,3-diyl]bis(2-methylpropanenitrile)

17. Chebi:2704

18. Rvg-106400

19. Nsc719344

20. Ncgc00164619-01

21. Asiolex

22. Dsstox_cid_2607

23. 2-[3-(1-cyano-1-methylethyl)-5-(1h-1,2,4-triazol-1-ylmethyl)phenyl]-2-methylpropanenitrile

24. Dsstox_rid_76656

25. Dsstox_gsid_22607

26. Alpha1,alpha1,alpha3,alpha3-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-1,3-benzenediacetonitrile

27. Zd 1033

28. Arimidex (tn)

29. Smr000466301

30. Cas-120511-73-1

31. Hsdb 7462

32. Ici-d 1033

33. Sr-01000759390

34. Unii-2z07myw1az

35. Ccris 9352

36. Anastrozole [usan:usp:inn:ban]

37. Anastrozole- Bio-x

38. Arimidex (astrazeneca)

39. Anastrozole [mi]

40. Anastrozole [inn]

41. Anastrozole [jan]

42. Anastrozole [hsdb]

43. Anastrozole [usan]

44. Schembl9726

45. Anastrozole [mart.]

46. Anastrozole [usp-rs]

47. Anastrozole [who-dd]

48. Zinc941

49. 1,3-benzenediacetonitrile, Alpha,alpha,alpha',alpha'-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-

50. Mls000759396

51. Mls001424217

52. Mls006011961

53. Anastrozole (jan/usp/inn)

54. Gtpl5137

55. Dtxsid9022607

56. Bdbm10015

57. Anastrozole [orange Book]

58. Anastrozole [ep Monograph]

59. Anastrozole [usp Impurity]

60. Bcpp000401

61. Hms2052m11

62. Hms2089n10

63. Hms2235m06

64. Hms3369k05

65. Hms3394m11

66. Hms3654i18

67. Hms3715b05

68. Hms3742o21

69. Hms3866k03

70. Pharmakon1600-01502278

71. Anastrozole [usp Monograph]

72. Act03222

73. Amy42020

74. Bcp02090

75. Tox21_112238

76. Tox21_303568

77. Mfcd00866298

78. Nsc759855

79. S1188

80. Stl451008

81. Akos015894980

82. Tox21_112238_1

83. Ac-4234

84. Bcp9000301

85. Ccg-101109

86. Cs-0716

87. Db01217

88. Ks-5052

89. Nc00359

90. Nsc 719344

91. Nsc 759855

92. Sb17304

93. 2,2'-[5-(1h-1,2,4-triazol-1-ylmethyl)-1,3-phenylene]bis(2-methylpropanenitrile)

94. Ncgc00164619-02

95. Ncgc00164619-04

96. Ncgc00257356-01

97. Bt164176

98. Hy-14274

99. Sw197739-4

100. 11a731

101. C08159

102. D00960

103. Ab00639929-06

104. Ab00639929-08

105. Ab00639929-09

106. Ab00639929-10

107. Ab00639929_11

108. Ab00639929_13

109. A804526

110. Q419143

111. Sr-01000759390-4

112. Sr-01000759390-5

113. Z1522566626

114. 3-amino-3-(4-diethylamino-2-hydroxy-phenyl)-propionicacid

115. 1,.alpha.,alpha.,alpha.',.alpha.'-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-

116. 2,2'-[5-(1h-1,2,4-triazol-1-yl-methyl)-1,3-phenylene]-di(2-methyl Propionitrile)

117. 2,2'-[5-(1h-1,2,4-triazol-1-ylmethyl)-1,3-phenylene]di(2-methylpropiononitrile)

118. 2,2'-[5-(1h-1,2,4-triazole-1-yl-methyl)-1,3-phenylene]di(2-methyl Propionitrile)

119. 2-[3-(2-cyano-2-propyl)-5-(1,2,4-triazol-1-ylmethyl)phenyl]-2-methylpropiononitrile

120. 2-[3-(2-cyanopropan-2-yl)-5-(1,2,4-triazol-1-ylmethyl)phenyl]-2-methyl-propanenitrile

121. .alpha.,.alpha.',.alpha.'-tetramethyl-5(1h-1,2,4-triazol-1-ylmethyl)-m-benzenediacetonitrile

122. .alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-m-benzenediacetonitrile

123. 1,3-benzenediacetonitrile,.alpha.,.alpha.,.alpha.',.alpha.'-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-

124. 2-[3-(1-cyano-1-methylethyl)-5-[(1h-1,2,4-triazol-1-yl)methyl]phenyl]-2-methylpropanenitrile

125. Alpha,alpha,alpha',alpha'-tetramethyl-5-(1h-1,2,4-triazol-1-ylmethyl)-1,3-benzenediacetonitrile

2.4 Create Date
2005-03-25
3 Chemical and Physical Properties
Molecular Weight 293.4 g/mol
Molecular Formula C17H19N5
XLogP32.1
Hydrogen Bond Donor Count0
Hydrogen Bond Acceptor Count4
Rotatable Bond Count4
Exact Mass293.16404563 g/mol
Monoisotopic Mass293.16404563 g/mol
Topological Polar Surface Area78.3 Ų
Heavy Atom Count22
Formal Charge0
Complexity456
Isotope Atom Count0
Defined Atom Stereocenter Count0
Undefined Atom Stereocenter Count0
Defined Bond Stereocenter Count0
Undefined Bond Stereocenter Count0
Covalently Bonded Unit Count1
4 Drug and Medication Information
4.1 Drug Information
1 of 4  
Drug NameAnastrozole
PubMed HealthAnastrozole (By mouth)
Drug ClassesAntineoplastic Agent, Endocrine-Metabolic Agent
Drug LabelAnastrozole tablets for oral administration contain 1 mg of anastrozole, a non-steroidal aromatase inhibitor. It is chemically described as 1,3-Benzenediacetonitrile, a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1-ylmethyl). Its molecular formul
Active IngredientAnastrozole
Dosage FormTablet
RouteOral
Strength1mg
Market StatusPrescription
CompanySantos Biotech; Teva Pharms; Fresenius Kabi Oncol; Apotex; Accord Hlthcare; Sun Pharm Inds; Natco Pharma; Zydus Pharms Usa; Dr Reddys Labs; Sandoz; Three Rivers Pharms; Mylan; Roxane

2 of 4  
Drug NameArimidex
PubMed HealthAnastrozole (By mouth)
Drug ClassesAntineoplastic Agent, Endocrine-Metabolic Agent
Drug LabelARIMIDEX (anastrozole) tablets for oral administration contain 1 mg of anastrozole, a non-steroidal aromatase inhibitor. It is chemically described as 1,3-Benzenediacetonitrile, a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1-ylmethyl). Its molec
Active IngredientAnastrozole
Dosage FormTablet
Routeoral; Oral
Strength1mg
Market StatusPrescription
CompanyAstrazeneca

3 of 4  
Drug NameAnastrozole
PubMed HealthAnastrozole (By mouth)
Drug ClassesAntineoplastic Agent, Endocrine-Metabolic Agent
Drug LabelAnastrozole tablets for oral administration contain 1 mg of anastrozole, a non-steroidal aromatase inhibitor. It is chemically described as 1,3-Benzenediacetonitrile, a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1-ylmethyl). Its molecular formul
Active IngredientAnastrozole
Dosage FormTablet
RouteOral
Strength1mg
Market StatusPrescription
CompanySantos Biotech; Teva Pharms; Fresenius Kabi Oncol; Apotex; Accord Hlthcare; Sun Pharm Inds; Natco Pharma; Zydus Pharms Usa; Dr Reddys Labs; Sandoz; Three Rivers Pharms; Mylan; Roxane

4 of 4  
Drug NameArimidex
PubMed HealthAnastrozole (By mouth)
Drug ClassesAntineoplastic Agent, Endocrine-Metabolic Agent
Drug LabelARIMIDEX (anastrozole) tablets for oral administration contain 1 mg of anastrozole, a non-steroidal aromatase inhibitor. It is chemically described as 1,3-Benzenediacetonitrile, a, a, a', a'-tetramethyl-5-(1H-1,2,4-triazol-1-ylmethyl). Its molec
Active IngredientAnastrozole
Dosage FormTablet
Routeoral; Oral
Strength1mg
Market StatusPrescription
CompanyAstrazeneca

4.2 Therapeutic Uses

Antineoplastic

O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. 13th Edition, Whitehouse Station, NJ: Merck and Co., Inc., 2001., p. 105


Anastrozole is indicated for the first-line treatment of postmenopausal woman with hormone receptor positive or hormone receptor unknown locally advanced or metastatic breast cancer. It is also indicated for treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. /Included in US product label/

Thomson/Micromedex. Drug Information for the Health Care Professional. Volume 1, Greenwood Village, CO. 2006., p. 151


Anastrozole is an option for the neoadjuvant treatment of hormone receptorpositive, locally advanced breast cancer in postmenopausal women. Two phase 2, randomized, double-blind clinical trials found anastrozole to be at least as effective as tamoxifen in response rates and rates of improved surgery. A phase 2, unpublished abstract reported no differences between neoadjuvant anastrozole and chemotherapy (doxorubicin and paclitaxel) in response rates, number of patients qualifying for breast-conserving surgery, and 3-year disease-free survival. An international expert panel recommends neoadjuvant endocrine therapy in postmenopausal women who would benefit from preoperative chemotherapy but are ineligible to receive it. Anastrozole was well-tolerated. /Not included in US product label/

Thomson/Micromedex. Drug Information for the Health Care Professional. Volume 1, Greenwood Village, CO. 2006., p. 151


Anastrozole is not recommended for use in premenopausal women. Safety and efficacy have not been established. /Included in US product label/

Thomson/Micromedex. Drug Information for the Health Care Professional. Volume 1, Greenwood Village, CO. 2006., p. 151


For more Therapeutic Uses (Complete) data for ANASTROZOLE (8 total), please visit the HSDB record page.


4.3 Drug Warning

Among patients receiving adjuvant therapy, venous thromboembolic events occurred less frequently in patients receiving anastrozole than in those receiving tamoxifen (2 versus 4%); this included deep venous thrombosis (1 versus 2%). Ischemic cerebrovascular events also occurred less frequently in patients receiving anastrozole compared with those receiving tamoxifen (1 versus 2%). Ischemic cardiovascular disease was reported in 3% of such patients receiving anastrozole. Although angina pectoris was reported more frequently in patients receiving adjuvant therapy with anastrozole than in those receiving tamoxifen (about 2 versus 1%), the incidence of myocardial infarction was similar (0.8%).

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 927


Among patients receiving anastrozole as first-line therapy, thromboembolic disease was reported in 18 patients (4%), with 5 patients experiencing venous thrombosis (including pulmonary embolus, thrombophlebitis, and retinal vein thrombosis) and 13 patients experiencing coronary and/or cerebral thrombosis (including myocardial infarction, myocardial ischemia, angina pectoris, cerebrovascular accident, cerebral ischemia, and cerebral infarct). Despite its lack of estrogenic activity, there was no evidence of an increased incidence of myocardial infarction in patients receiving anastrozole compared with those receiving tamoxifen.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 927


Among patients receiving anastrozole as second-line therapy, thromboembolic disease was reported in 3%, and thrombophlebitis occurred in 2-5%.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 927


Among patients receiving adjuvant therapy, hot flushes (flashes) occurred less frequently in patients receiving anastrozole than in those receiving tamoxifen (35 versus 40%). Among patients receiving anastrozole as first-line or second-line therapy, hot flushes occurred in 26 or 13%, respectively.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 927


For more Drug Warnings (Complete) data for ANASTROZOLE (35 total), please visit the HSDB record page.


4.4 Drug Indication

Anastrozole is indicated as adjunct therapy in the treatment of hormone receptor-positive early breast cancer in postmenopausal women, and as a first-line treatment for hormone receptor-positive (or hormone receptor-unknown) locally advanced or metastatic breast cancer in postmenopausal women. It may also be used in the treatment of advanced breast cancer in postmenopausal women who experience disease progression despite treatment with [tamoxifen].


Gynaecomastia, McCune-Albright syndrome, Short stature due to Growth Hormone deficiency, Testotoxicosis


5 Pharmacology and Biochemistry
5.1 Pharmacology

Anastrozole prevents the conversion of adrenal androgens (e.g. [testosterone]) to estrogen in peripheral and tumour tissues. As the growth of many breast cancers is stimulated and/or maintained by the presence of estrogen, anastrozole helps to treat these cancers by decreasing the levels of circulating estrogens. Anastrozole has a relatively long duration of action allowing for once daily dosing - serum estradiol is reduced by approximately 70% within 24 hours of beginning therapy with 1mg once daily, and levels remain suppressed for up to 6 days following cessation of therapy. The incidence of ischemic cardiovascular events was increased during anastrozole therapy and patients with pre-existing ischemic heart disease should consider the risks and benefits of anastrozole before beginning therapy. Anastrozole has also been reported to decrease spine and hip bone mineral density (BMD), so consideration should be given to monitoring of BMD in patients receiving long-term therapy.


5.2 MeSH Pharmacological Classification

Antineoplastic Agents, Hormonal

Antineoplastic agents that are used to treat hormone-sensitive tumors. Hormone-sensitive tumors may be hormone-dependent, hormone-responsive, or both. A hormone-dependent tumor regresses on removal of the hormonal stimulus, by surgery or pharmacological block. Hormone-responsive tumors may regress when pharmacologic amounts of hormones are administered regardless of whether previous signs of hormone sensitivity were observed. The major hormone-responsive cancers include carcinomas of the breast, prostate, and endometrium; lymphomas; and certain leukemias. (From AMA Drug Evaluations Annual 1994, p2079) (See all compounds classified as Antineoplastic Agents, Hormonal.)


Aromatase Inhibitors

Compounds that inhibit AROMATASE in order to reduce production of estrogenic steroid hormones. (See all compounds classified as Aromatase Inhibitors.)


5.3 FDA Pharmacological Classification
5.3.1 Active Moiety
ANASTROZOLE
5.3.2 FDA UNII
2Z07MYW1AZ
5.3.3 Pharmacological Classes
Aromatase Inhibitors [MoA]; Aromatase Inhibitor [EPC]
5.4 ATC Code

L02BG03

S76 | LUXPHARMA | Pharmaceuticals Marketed in Luxembourg | Pharmaceuticals marketed in Luxembourg, as published by d'Gesondheetskeess (CNS, la caisse nationale de sante, www.cns.lu), mapped by name to structures using CompTox by R. Singh et al. (in prep.). List downloaded from https://cns.public.lu/en/legislations/textes-coordonnes/liste-med-comm.html. Dataset DOI:10.5281/zenodo.4587355


L - Antineoplastic and immunomodulating agents

L02 - Endocrine therapy

L02B - Hormone antagonists and related agents

L02BG - Aromatase inhibitors

L02BG03 - Anastrozole


5.5 Absorption, Distribution and Excretion

Absorption

Anastrozole is rapidly absorbed and Tmax is typically reached within 2 hours of dosing under fasted conditions. Coadministration with food reduces the rate but not the overall extent of absorption - mean Cmax decreased by 16% and the median Tmax was extended to 5 hours when anastrozole was administered 30 minutes after ingestion of food, though this relatively minor alteration in absorption kinetics is not expected to result in clinically significant effects.


Route of Elimination

Hepatic metabolism accounts for approximately 85% of anastrozole elimination. Approximately 10% of the administered dosage is eliminated unchanged in the urine.


Volume of Distribution

The volume of distribution of anastrozole into brain tissue in mice is 3.19 mL/g. Distribution into the CNS is limited due to the activity of P-gp efflux pumps at the blood brain barrier, of which anastrozole is a substrate.


Clearance

Anastrozole's clearance is mainly via hepatic metabolism and can therefore be altered in patients with hepatic impairment - patients with stable hepatic cirrhosis exhibit an apparent oral clearance approximately 30% lower compared with patients with normal liver function. Conversely, renal impairment has a negligible effect on total drug clearance as the renal route is a relatively minor clearance pathway for anastrozole. In volunteers with severe renal impairment, renal clearance was reduced by 50% while total clearance was only reduced by approximately 10%.


Anastrozole is well absorbed into systemic circulation following oral administration. Plasma concentrations approach steady-state at about 7 days of once-daily dosing, and steady-state concentrations are approximately 3-4 times higher than concentrations achieved after a single dose of the drug. Food does not affect the extent of oral absorption of anastrozole.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 930


Within the therapeutic plasma concentration range, anastrozole is 40% bound to plasma proteins.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 930


Steady-state minimum plasma concentrations averaged 25.7 and 30.4 ng/mL, respectively, in white and Japanese postmenopausal women receiving anastrozole 1 mg daily for 16 days; serum estradiol and estrone sulfate concentrations were similar between the groups.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 930


It is not known whether anastrozole is distributed into milk in humans.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 930


For more Absorption, Distribution and Excretion (Complete) data for ANASTROZOLE (10 total), please visit the HSDB record page.


5.6 Metabolism/Metabolites

Anastrozole is primarily metabolized in the liver via oxidation and glucuronidation to a number of inactive metabolites, including hydroxyanastrozole (both free and glucuronidated) and anastrozole glucuronide. Oxidation to hydroxyanastrozole is catalyzed predominantly by CYP3A4 (as well as CYP3A5 and CYP2C8, to a lesser extent) and the direct glucuronidation of anastrozole appears to be catalyzed mainly by UGT1A4. Anastrozole may also undergo N-dealkylation to form triazole and 3,5-Bis-(2-methylpropiononitrile)-benzoic acid. Labels for anastrozole state the main metabolite found in plasma following administration is triazole, but a recent pharmacokinetic study was unable to detect any products of N-dealkylation _in vitro_.


Anastrozole is extensively metabolized in the liver. Metabolism of anastrozole occurs via N-dealkylation, hydroxylation, and glucuronidation. Three metabolites of anastrozole have been identified in human plasma and urine: triazole, a glucuronide conjugate of anastrozole, and a glucuronide conjugate of hydroxyanastrozole. Triazole, the major circulating metabolite of anastrozole, lacks pharmacologic activity, and the aromatase inhibiting activity of anastrozole results principally from the parent drug. In addition, there are several minor metabolites of anastrozole, accounting for less than 5% of an administered dose, which have not been identified.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 929


5.7 Biological Half-Life

The elimination half-life of anastrozole is approximately 50 hours.


Following oral administration of anastrozole in postmenopausal women, a mean terminal elimination half-life of approximately 50 hours has been reported.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 930


5.8 Mechanism of Action

Anastrazole exerts its anti-estrogenic effects via selective and competitive inhibition of the aromatase enzyme found predominantly in the adrenal glands, liver, and fatty tissues. Many breast cancers are hormone receptor-positive, meaning their growth is stimulated and/or maintained by the presence of hormones such as estrogen or progesterone. In postmenopausal women, estrogen is primarily derived from the conversion of adrenally-produced androgens into estrogens by the aromatase enzyme - by competitively inhibiting the biosynthesis of estrogen at these enzymes, anastrozole effectively suppresses circulating estrogen levels and, subsequently, the growth of hormone receptor-positive tumours.


Anastrozole is a nonsteroidal aromatase inhibitor that interferes with estradiol production in peripheral tissues. Adrenally generated androstenedione, the chief source of circulating estrogen in postmenopausal women, is converted by aromatase to estrone, which is further converted to estradiol. Growth of many breast cancer tumors containing estrogen receptors and aromatase can be promoted by estrogen.

Thomson/Micromedex. Drug Information for the Health Care Professional. Volume 1, Greenwood Village, CO. 2006., p. 151


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.

Physicians Desk Reference 60th ed, Thomson PDR, Montvale, NJ 2006., p. 666


Because estrogen acts as a growth factor for hormone-dependent breast cancer cells, anastrozole-induced reduction of serum and tumor concentrations of estrogen inhibits tumor growth and delays disease progression. Anastrozole selectively inhibits the conversion of androgens to estrogens. In postmenopausal women, ovarian secretion of estrogen declines and conversion of adrenal androgens (mainly androstenedione and testosterone) to estrone and estradiol in peripheral tissues (adipose, muscle, and liver), catalyzed by the aromatase enzyme, is the principal source of estrogens. Anastrozole inhibits the aromatase enzyme by competitively binding to the heme of the cytochrome P-450 unit of the enzyme; suppression of estrogen biosynthesis in all tissues reduces serum concentrations of circulating estrogens, including estrone, estradiol, and estrone sulfate. Anastrozole selectively inhibits synthesis of estrogens and does not affect synthesis of adrenal corticosteroid, aldosterone, or thyroid hormone. In animals, anastrozole has not been shown to possess direct progestogenic, androgenic, or estrogenic activity, but alterations in the circulating concentrations of progesterone, androgens, and estrogens have been observed.

McEvoy, G.K. (ed.). American Hospital Formulary Service. AHFS Drug Information. American Society of Health-System Pharmacists, Bethesda, MD. 2006., p. 929