Anastrozole is a selective and very effective nonsteroidal aromatase inhibitor. It inhibits the conversion of:

• Androstenedione to estrone and
• Testosterone to estradiol.

Anastrozole Indications:

• As a first-line treatment of breast cancer in postmenopausal women that is hormone sensitive (HER-positive), locally-advanced or has metastasized.

• As adjuvant treatment of breast cancer (hormone sensitive) in postmenopausal women in its early stages.

• Postmenopausal women with advanced breast cancer that has progressed even after treatment with Tamoxifen.

• Endometrial or uterine cancers that are recurrent or that have metastasized.

• Recurrent ovarian cancer

• For reducing the risk of breast cancer in postmenopausal women who are at a high risk.

It is one of the WHO's List Of Essential Medicine

Anastrozole Dose in Adults

Anastrozole dose in the treatment of advanced Breast cancer in postmenopausal women:

• 1 mg orally once a day.
• The treatment is continued until the disease has progressed or the drug is no more tolerated.

Dose in estrogen-receptor-positive and HER2-negative advanced Breast cancer (off-label use):

• Postmenopausal females:
  • 1 mg orally once a day until the drug is no more tolerated because of side effects or the disease has progressed.
  • It is used in combination with abemaciclib.
• Premenopausal or perimenopausal females:
  • 1 mg orally once a day until intolerable side effects or the diseases progresses.
  • It is used in combination with ribociclib and goserelin.

Anastrozole dose in the treatment as adjuvant therapy of early Breast cancer:

• Postmenopausal females:
  • 1 mg orally once a day
• Duration of therapy:
  • The ASCO guidelines recommend a maximum treatment duration of five years for postmenopausal women.
  • The treatment duration may be extended to 10 years when combined with Tamoxifen.
  • Further extension of the treatment is a decision to be taken by the treating oncologist.

Anastrozole Dose in the treatment of risk reduction of Breast cancer as off-label use:

• Postmenopausal females older than 40 years of age:
  • 1 mg orally once a day for 5 years.

Anastrozole dose (off-lable) for recurrent or metastatic endometrial or uterine cancer:

• 1 mg orally once a day.

Anastrozole dose (off-lable)  in the treatment of recurrent Ovarian cancer:

• 1 mg orally once daily.
• The treatment is continued until intolerable side effects or the disease progresses despite the treatment.

Pregnancy Risk Factor: X

• Anastrozole can have serious adverse effects on the fetal health.
• Before starting therapy, a pregnancy test must be done.
• Effective contraception should be used by women in their reproductive years.

Use of anastrozole while breastfeeding

• It is unknown if the drug enters human breastmilk or not.
• Because of possible serious side effects, the manufacturer suggests that breastfeeding be stopped.

Anastrozole Dose in Renal Disease:

• No dose adjustment is necessary.

Anastrozole Dose in Liver Disease:

• Mild to moderate and stable hepatic impairment:
  • Adjustment in the dose is not necessary.
• Severe hepatic impairment:
  • The manufacturer has not recommended any adjustment in the dose in patients with severe hepatic impairment.

Common Side Effects of Anastrozole:

• Cardiovascular:
  • Vasodilatation
  • Ischemic Heart Disease
  • Hypertension
  • Angina Pectoris
  • Edema
• Central Nervous System:
  • Fatigue
  • Mood Disorder
  • Headache
  • Pain
  • Depression
• Dermatologic:
  • Skin Rash
• Endocrine & Metabolic:
  • Hot Flash
• Gastrointestinal:
  • Gastrointestinal Distress
  • Nausea
  • Vomiting
• Neuromuscular & Skeletal:
  • Weakness
  • Arthritis
  • Arthralgia
  • Back Pain
  • Ostealgia
  • Osteoporosis
• Respiratory:
  • Pharyngitis
  • Dyspnea
  • Increased Cough

Less Common Side Effects Of Anastrozole:

• Cardiovascular:
  • Peripheral Edema
  • Chest Pain
  • Venous Thrombosis
  • Myocardial Infarction
• Central Nervous System:
  • Insomnia
  • Dizziness
  • Paresthesia
  • Anxiety
  • Confusion
  • Drowsiness
  • Malaise
  • Nervousness
  • Carpal Tunnel Syndrome
  • Hypertonia
  • Cerebrovascular Insufficiency
  • Lethargy
• Dermatologic:
  • Alopecia
  • Pruritus
  • Diaphoresis
• Endocrine & Metabolic:
  • Hypercholesterolemia
  • Increased Serum Cholesterol
  • Weight Gain
  • Increased Gamma-Glutamyl Transferase
  • Weight Loss
• Gastrointestinal:
  • Constipation
  • Diarrhea
  • Abdominal Pain
  • Anorexia
  • Dyspepsia
  • Gastrointestinal Disease
  • Xerostomia
• Genitourinary:
  • Mastalgia
  • Urinary Tract Infection
  • Pelvic Pain
  • Vulvovaginitis
  • Vaginal Dryness
  • Vaginal Hemorrhage
  • Vaginal Discharge
  • Vaginitis
  • Leukorrhea
• Hematologic & Oncologic:
  • Lymphedema
  • Breast Neoplasm
  • Neoplasm
  • Anemia
  • Leukopenia
  • Tumor Flare
• Hepatic:
  • Deranged LFTs (Raised alkaline Phosphatase, ALT, and AST)
• Infection:
  • Infection
• Neuromuscular & Skeletal:
  • Bone Fracture
  • Arthrosis
  • Myalgia
  • Neck Pain
  • Pathological Fracture
• Ophthalmic:
  • Cataract
• Respiratory:
  • Flu-Like Symptoms
  • Sinusitis
  • Bronchitis
  • Rhinitis
• Miscellaneous:
  • Accidental Injury
  • Cyst
  • Fever

Contraindications to Anastrozole Treatment:

• Allergy to anastrozole
• Pregnancy
• Breastfeeding

Warnings and Precautions

• Reduced bone mineral density

Anastrozole inhibits estrogen and hence, reduces bone mineral density. The risk of fractures is increased with prolonged treatment.

Patients who have osteopenia before starting therapy are more likely to develop osteoporosis.

To reduce fracture risk, patients should be checked for osteoporosis. Bisphosphonates can be recommended.

• Hypercholesterolemia

Anastrozole can raise LDL cholesterol. Patients with dyslipidemias should not use it.

Patients must be monitored and treated according to the guidelines for statin use.

• Hypersensitivity

Allergy reactions can occur in patients, ranging from anaphylaxis to angioedema, itching, and urticaria.

• Hepatic impairment

Patients with severe hepatic impairment have not had it studied and should be cautious.

• Ischemic Disease:

Treatment may theoretically increase the risk of ischemic heart disease. Patients with preexisting ischemic cardiac disease should be cautious about taking the drug.

Anastrozole: Drug Interaction

Note: Drug Interaction Categories:

• Risk Factor C: Monitor When Using Combination
• Risk Factor D: Consider Treatment Modification
• Risk Factor X: Avoid Concomitant Use

Monitoring Parameters:

• Bone mineral density
• Lipid profile including total cholesterol and LDL
• Pregnancy test in females of reproductive age groups before the start of therapy.
• Monitor drug adherence
• Mammogram and breast examination at baseline and every 2 years when prescribed for breast cancer risk reduction.

How to take Anastrozole? 

• It may be administered orally with or without food.

Mechanism of action of Anastrozole:

It is a very effective and selective nonsteroidal aromatase inhibitor. It prevents androstenedione from being converted to estrogen and testosterone from estradiol.

This inhibits aromatase and slows down the progression of patients with hormone-responsive tumors. It decreases the estrone sulfate level by 85%.

It takes approximately 24 hours to reduce estrogen by 70%, and about 2 weeks to reduce it to 80%. 

It is known to have a duration of action of 6 Days. Its absorption is not affected by foods. 

40% of the drug is Proteins bound. It is Metabolized By the liver to inactive metabolites.

It has an Eliminating half-life of approximately 50 hours, and the time it takes to reach Peak plasma concentration is about 2 hours when administer without food, and 5 hours when administer with food.

It is excreted in the feces.  

International Brands of Anastrozole:

• ACH-Anastrozole
• ACT Anastrozole
• APO-Anastrozole
• Arimidex
• Auro-Anastrozole
• BIO-Anastrozole
• CCP-Anastrozole
• JAMP-Anastrozole
• Mar-Anastrozole
• MED-Anastrozole
• MINT-Anastrozole
• MYLAN-Anastrozole
• NAT-Anastrozole
• PMS-Anastrozole
• RAN-Anastrozole
• RIVA-Anastrozole
• SANDOZ Anastrozole
• TARO-Anastrozole
• TEVA-Anastrozole
• VAN-Anastrozole
• Zinda-Anastrozole
• A-Dex
• Agerdex
• Alozex
• Altraz
• Amidex
• Anaccord
• Anaglob
• Anamidex
• Anarix
• Anarom
• Anaromat
• Anastralex
• Anastrodex
• Anastrol
• Anatero
• Anatrole
• Anazo
• Anazole
• Anzonat
• Anzucia
• Aremed
• Aremed 1
• Arimidex
• Ariniq
• Armida
• Armotraz
• Aromatt-1
• Axastrol
• Azonet
• Egistrozol
• Femistra
• Gondonar
• Leprofen
• Madelen
• Ozolan
• Sananas
• Trozolite
• Vexal-A
• Victeve
• Zanazole
• Zolasatin
• Zortex

Anastrozole Brands in Pakistan: