Anastrozole 1mg Tablets
It is used to treat breast cancer after menopause. If you have been given this drug for some other reason, talk with your doctor for more information.
Drug Class
Antineoplastic Agent
Pharmacologic Class
Aromatase Inhibitor
Pregnancy Category
Category X
FDA Approved
Dec 1995
DEA Schedule
Not Controlled
Overview
What is this medicine?
Anastrozole is a medicine used to treat breast cancer in women who have gone through menopause. It works by lowering the amount of estrogen in the body, which can help stop the growth of certain types of breast cancer that need estrogen to grow.
How to Use This Medicine
Taking Your Medication
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. Continue taking it even if you feel well, unless your doctor or healthcare provider advises you to stop.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms. Keep all medications in a safe location, out of reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposal, consult your pharmacist. You may also want to check if there are drug take-back programs available in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
To use this medication correctly, follow your doctor's instructions and read all the information provided. Take your medication as directed, with or without food. Continue taking it even if you feel well, unless your doctor or healthcare provider advises you to stop.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms. Keep all medications in a safe location, out of reach of children and pets. Dispose of unused or expired medications properly. Do not flush them down the toilet or pour them down the drain unless instructed to do so. If you have questions about disposal, consult your pharmacist. You may also want to check if there are drug take-back programs available in your area.
Missing a Dose
If you miss a dose, take it as soon as you remember. However, if it's close to the time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at the same time or take extra doses to make up for the missed one.
Lifestyle & Tips
- Take calcium and vitamin D supplements as recommended by your doctor to help protect your bones.
- Engage in regular weight-bearing exercise (e.g., walking, jogging, weightlifting) to help maintain bone density.
- Maintain a healthy diet rich in fruits, vegetables, and whole grains.
- Avoid smoking and limit alcohol intake, as these can negatively impact bone health and overall well-being.
- Discuss strategies with your doctor for managing common side effects like hot flashes and joint pain.
Available Forms & Alternatives
Available Strengths:
Dosing & Administration
Adult Dosing
Standard Dose:
1 mg orally once daily
Dose Range:
1 - 1 mg
Condition-Specific Dosing:
adjuvant_treatment_of_postmenopausal_women_with_hormone_receptor_positive_early_breast_cancer:
1 mg orally once daily
first_line_treatment_of_postmenopausal_women_with_hormone_receptor_positive_or_hormone_receptor_unknown_locally_advanced_or_metastatic_breast_cancer:
1 mg orally once daily
treatment_of_advanced_breast_cancer_in_postmenopausal_women_with_disease_progression_following_tamoxifen_therapy:
1 mg orally once daily
Pediatric Dosing
Neonatal:
Not established
Infant:
Not established
Child:
Not established
Adolescent:
Not established
Dose Adjustments
Renal Impairment:
Mild:
No dose adjustment required
Moderate:
No dose adjustment required
Severe:
No dose adjustment required (limited data, use with caution)
Dialysis:
Not studied, unlikely to be significantly removed by dialysis due to high protein binding and metabolism.
Hepatic Impairment:
Mild:
No dose adjustment required
Moderate:
No dose adjustment required
Severe:
No dose adjustment required (limited data, use with caution)
Pharmacology
Mechanism of Action
Anastrozole is a potent and highly selective non-steroidal aromatase inhibitor. It inhibits the enzyme aromatase, which is responsible for the conversion of androgens (primarily androstenedione and testosterone) to estrogens (estrone and estradiol) in peripheral tissues. In postmenopausal women, estrogen production from the adrenal glands is the primary source of circulating estrogens. By inhibiting aromatase, anastrozole significantly reduces circulating estrogen levels, thereby depriving estrogen-dependent breast cancer cells of growth stimulation.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 85%
Tmax:
2-3 hours
FoodEffect:
Food may slightly decrease the rate of absorption but does not affect the extent of absorption.
Distribution:
Vd:
Approximately 19 L
ProteinBinding:
Approximately 40%
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 40-50 hours
Clearance:
Not readily quantifiable due to extensive metabolism
ExcretionRoute:
Primarily renal (approximately 60% as metabolites, 10% unchanged drug) and fecal (approximately 10% as metabolites)
Unchanged:
Approximately 10%
Pharmacodynamics
OnsetOfAction:
Significant estrogen suppression within 24 hours
PeakEffect:
Steady-state plasma concentrations reached in approximately 7 days; maximal estrogen suppression achieved within days of starting therapy.
DurationOfAction:
Prolonged due to long half-life, maintaining estrogen suppression for several days after discontinuation.
Safety & Warnings
Side Effects
Serious Side Effects: Seek Medical Help Right Away
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of high blood pressure, such as:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Signs of a urinary tract infection (UTI), including:
+ Blood in the urine
+ Burning or pain when passing urine
+ Frequent or urgent need to urinate
+ Fever
+ Lower stomach pain
+ Pelvic pain
Abnormal sensations, such as:
+ Burning
+ Numbness
+ Tingling
Swollen glands
Bone pain
Shortness of breath
Swelling in the arms or legs
Depression or other mood changes
Changes in eyesight
Breast pain
Abnormal vaginal bleeding
Vaginal itching or discharge
If you have a history of ischemic heart disease (blockage in the heart blood vessels), you may be more likely to experience symptoms related to poor blood flow to the heart. Seek medical help immediately if you experience new or worsening chest pain or shortness of breath.
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, contact your doctor or seek medical help if they bother you or persist:
Hot flashes
Dizziness, tiredness, or weakness
Headache
Constipation, diarrhea, stomach pain, upset stomach, vomiting, or decreased appetite
Heartburn
Back, muscle, or joint pain
Joint swelling
Pelvic pain
Trouble sleeping
Cough
Sore throat
Weight gain
Anxiety
Excessive sweating
Flu-like symptoms
Dry mouth
This is not an exhaustive list of possible side effects. If you have questions or concerns, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Although rare, some people may experience severe and potentially life-threatening side effects while taking this medication. If you notice any of the following symptoms, contact your doctor immediately or seek medical attention:
Signs of an allergic reaction, such as:
+ Rash
+ Hives
+ Itching
+ Red, swollen, blistered, or peeling skin with or without fever
+ Wheezing
+ Tightness in the chest or throat
+ Trouble breathing, swallowing, or talking
+ Unusual hoarseness
+ Swelling of the mouth, face, lips, tongue, or throat
Signs of liver problems, including:
+ Dark urine
+ Tiredness
+ Decreased appetite
+ Upset stomach or stomach pain
+ Light-colored stools
+ Vomiting
+ Yellow skin or eyes
Signs of high blood pressure, such as:
+ Severe headache or dizziness
+ Passing out
+ Changes in eyesight
Signs of a urinary tract infection (UTI), including:
+ Blood in the urine
+ Burning or pain when passing urine
+ Frequent or urgent need to urinate
+ Fever
+ Lower stomach pain
+ Pelvic pain
Abnormal sensations, such as:
+ Burning
+ Numbness
+ Tingling
Swollen glands
Bone pain
Shortness of breath
Swelling in the arms or legs
Depression or other mood changes
Changes in eyesight
Breast pain
Abnormal vaginal bleeding
Vaginal itching or discharge
If you have a history of ischemic heart disease (blockage in the heart blood vessels), you may be more likely to experience symptoms related to poor blood flow to the heart. Seek medical help immediately if you experience new or worsening chest pain or shortness of breath.
Other Possible Side Effects
Like all medications, this drug can cause side effects. While many people may not experience any side effects or only minor ones, it's essential to discuss any concerns with your doctor. If you experience any of the following side effects, contact your doctor or seek medical help if they bother you or persist:
Hot flashes
Dizziness, tiredness, or weakness
Headache
Constipation, diarrhea, stomach pain, upset stomach, vomiting, or decreased appetite
Heartburn
Back, muscle, or joint pain
Joint swelling
Pelvic pain
Trouble sleeping
Cough
Sore throat
Weight gain
Anxiety
Excessive sweating
Flu-like symptoms
Dry mouth
This is not an exhaustive list of possible side effects. If you have questions or concerns, contact your doctor. You can also report side effects to the FDA at 1-800-332-1088 or online at https://www.fda.gov/medwatch.
Seek Immediate Medical Attention If You Experience:
- Sudden chest pain, shortness of breath, or coughing up blood (signs of blood clot in lungs)
- Swelling, pain, or redness in an arm or leg (signs of blood clot in leg)
- Sudden numbness or weakness, especially on one side of the body; sudden severe headache; sudden vision changes; sudden trouble speaking or understanding speech (signs of stroke)
- Severe skin reactions (e.g., rash, blistering, peeling skin)
- Unusual vaginal bleeding
- Yellowing of the skin or eyes (jaundice), dark urine, severe stomach pain (signs of liver problems)
- New or worsening bone pain
Before Using This Medicine
Before Taking This Medication: Important Information to Share with Your Doctor
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you are currently taking estrogen products or tamoxifen, as these may interact with this medication.
If you have not yet gone through menopause or are still capable of becoming pregnant.
If you are breastfeeding. Note that you should not breastfeed while taking this medication and for 2 weeks after your last dose.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health issues with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other drugs and health conditions. Never start, stop, or change the dosage of any medication without first consulting your doctor.
It is essential to inform your doctor about the following:
Any allergies you have, including allergies to this medication, its components, or other substances, such as foods or drugs. Be sure to describe the symptoms you experienced.
If you are currently taking estrogen products or tamoxifen, as these may interact with this medication.
If you have not yet gone through menopause or are still capable of becoming pregnant.
If you are breastfeeding. Note that you should not breastfeed while taking this medication and for 2 weeks after your last dose.
This list is not exhaustive, and it is crucial to discuss all your medications (including prescription, over-the-counter, natural products, and vitamins) and health issues with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other drugs and health conditions. Never start, stop, or change the dosage of any medication without first consulting your doctor.
Precautions & Cautions
It is essential to inform all your healthcare providers, including doctors, nurses, pharmacists, and dentists, that you are taking this medication. Regular blood tests and bone density checks should be performed as directed by your doctor.
This medication decreases estrogen levels in your body, which can lead to a loss of bone density, causing your bones to become thinner and weaker. This may increase the risk of fractures, particularly in the spine, hip, and wrist. Discuss this potential risk with your doctor.
There is a potential risk of developing high cholesterol while taking this medication. If you have concerns or questions, consult with your doctor.
This medication may also affect fertility, potentially impacting your ability to have children. Discuss this possibility with your doctor to understand the potential risks.
Additionally, this medication can cause harm to an unborn baby. To confirm you are not pregnant, a pregnancy test will be conducted before initiating treatment. If you may become pregnant, it is crucial to use birth control while taking this medication and for at least 3 weeks after your last dose. If you become pregnant, notify your doctor immediately.
This medication decreases estrogen levels in your body, which can lead to a loss of bone density, causing your bones to become thinner and weaker. This may increase the risk of fractures, particularly in the spine, hip, and wrist. Discuss this potential risk with your doctor.
There is a potential risk of developing high cholesterol while taking this medication. If you have concerns or questions, consult with your doctor.
This medication may also affect fertility, potentially impacting your ability to have children. Discuss this possibility with your doctor to understand the potential risks.
Additionally, this medication can cause harm to an unborn baby. To confirm you are not pregnant, a pregnancy test will be conducted before initiating treatment. If you may become pregnant, it is crucial to use birth control while taking this medication and for at least 3 weeks after your last dose. If you become pregnant, notify your doctor immediately.
Overdose Information
Overdose Symptoms:
- No specific antidote. Symptoms of overdose are not well established but would likely be an exaggeration of known side effects.
What to Do:
In case of suspected overdose, seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Management should be symptomatic and supportive, with monitoring of vital signs and general supportive care.
Drug Interactions
Contraindicated Interactions
- Estrogen-containing therapies (e.g., hormone replacement therapy, oral contraceptives)
Major Interactions
- Tamoxifen (concurrent use not recommended as it may reduce anastrozole plasma concentrations)
Monitoring
Baseline Monitoring
Bone Mineral Density (BMD) via DEXA scan
Rationale: Anastrozole can cause bone loss and increase fracture risk due to estrogen deprivation.
Timing: Prior to initiation of therapy
Lipid Profile (Total Cholesterol, LDL, HDL, Triglycerides)
Rationale: Anastrozole may cause increases in cholesterol levels.
Timing: Prior to initiation of therapy
Liver Function Tests (ALT, AST, Bilirubin)
Rationale: To assess baseline hepatic function, although severe hepatic impairment is rare.
Timing: Prior to initiation of therapy
Routine Monitoring
Bone Mineral Density (BMD) via DEXA scan
Frequency: Every 1-2 years, or as clinically indicated
Target: Maintain T-score above -2.5 (osteoporosis threshold)
Action Threshold: Significant bone loss or T-score indicating osteoporosis may warrant intervention (e.g., bisphosphonates, calcium/vitamin D supplementation).
Lipid Profile
Frequency: Periodically, as clinically indicated
Target: Within normal limits or individualized targets
Action Threshold: Significant elevations may require lifestyle modification or lipid-lowering agents.
Liver Function Tests
Frequency: Periodically, if clinically indicated or symptoms of hepatic dysfunction arise
Target: Within normal limits
Action Threshold: Significant elevations may require dose adjustment or discontinuation.
Symptom Monitoring
- Hot flashes
- Joint pain (arthralgia)
- Muscle pain (myalgia)
- Fatigue
- Vaginal dryness
- Mood disturbances (depression, anxiety)
- Headache
- Nausea
- Hair thinning
- Signs of thromboembolic events (e.g., chest pain, shortness of breath, leg swelling, sudden weakness/numbness)
- Signs of ischemic cardiovascular events (e.g., chest pain, discomfort, shortness of breath)
Special Patient Groups
Pregnancy
Anastrozole is contraindicated in pregnant women. It can cause fetal harm when administered to a pregnant woman. Based on animal studies, anastrozole may cause fetal malformations and embryo-fetal death.
Trimester-Specific Risks:
First Trimester:
High risk of fetal malformations and embryo-fetal death.
Second Trimester:
High risk of fetal malformations and embryo-fetal death.
Third Trimester:
High risk of fetal malformations and embryo-fetal death.
Lactation
It is not known whether anastrozole is excreted in human milk. Due to the potential for serious adverse reactions in breastfed infants, anastrozole is contraindicated during lactation. Breastfeeding is not recommended.
Infant Risk:
High risk of serious adverse effects due to potential for estrogen suppression in the infant.
Pediatric Use
The safety and effectiveness of anastrozole in pediatric patients have not been established. It is not indicated for use in children.
Geriatric Use
No dose adjustment is required for elderly patients. Clinical studies have shown similar efficacy and safety profiles in elderly patients compared to younger patients.
Clinical Information
Clinical Pearls
- Anastrozole should be taken at approximately the same time each day.
- It is crucial to monitor bone mineral density due to the increased risk of osteoporosis and fractures.
- Patients should be advised on strategies to manage common side effects such as hot flashes and arthralgia (joint pain).
- Anastrozole is only for postmenopausal women with hormone receptor-positive breast cancer.
- Patients should be educated on the signs and symptoms of thromboembolic events and cardiovascular events, which are potential risks.
Alternative Therapies
- Letrozole (another non-steroidal aromatase inhibitor)
- Exemestane (a steroidal aromatase inactivator)
- Tamoxifen (a selective estrogen receptor modulator, often used in premenopausal women or as an alternative in postmenopausal women)
- Fulvestrant (an estrogen receptor downregulator)
Cost & Coverage
Average Cost:
$10 - $50 per 30 tablets (generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 (generic); Tier 3 or Tier 4 (brand)
General Drug Facts
If your symptoms or health issues persist or worsen, it's essential to contact your doctor for further guidance. To ensure your safety, never share your medication with others or take someone else's medication. Some medications may come with an additional patient information leaflet, so be sure to check with your pharmacist for more details. If you have any questions or concerns about this medication, don't hesitate to reach out to your doctor, nurse, pharmacist, or other healthcare provider. In the event of a suspected overdose, immediately call your local poison control center or seek medical attention. When seeking help, be prepared to provide information about the medication taken, the amount, and the time it occurred.