Arimidex 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; Aromatase inhibitor
Pharmacologic Class
Nonsteroidal 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, and continue taking it even if you start feeling well. It's essential to adhere to your doctor's or healthcare provider's advice regarding the dosage and duration of treatment.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms and areas where children and pets can access it. Keep all medications in a safe location and dispose of unused or expired drugs properly. Do not flush medications down the toilet or pour them down the drain unless instructed to do so. If you're unsure about the best way to dispose of your medication, 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, and continue taking it even if you start feeling well. It's essential to adhere to your doctor's or healthcare provider's advice regarding the dosage and duration of treatment.
Storing and Disposing of Your Medication
Store your medication at room temperature in a dry place, avoiding bathrooms and areas where children and pets can access it. Keep all medications in a safe location and dispose of unused or expired drugs properly. Do not flush medications down the toilet or pour them down the drain unless instructed to do so. If you're unsure about the best way to dispose of your medication, 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 the tablet at the same time each day, with or without food.
- Do not stop taking the medication without consulting your doctor, even if you feel well.
- Discuss bone health with your doctor; calcium and vitamin D supplements may be recommended. Regular weight-bearing exercise can also help maintain bone density.
- Manage hot flashes with layered clothing, cool environments, and avoiding triggers. Discuss non-hormonal options with your doctor if severe.
- Report any new or worsening joint pain to your doctor.
- Stay hydrated and maintain a balanced diet.
- Avoid estrogen-containing products, including hormone replacement therapy and some herbal supplements, as they can interfere with anastrozole's effectiveness.
Available Forms & Alternatives
Available Strengths:
Generic Alternatives:
Dosing & Administration
Adult Dosing
Standard Dose:
1 mg orally once daily
Dose Range:
1 - 1 mg
Condition-Specific Dosing:
Adjuvant treatment of early breast cancer:
1 mg orally once daily for 5 years or until recurrence
First-line treatment of hormone receptor-positive 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, but caution is advised due to limited data
Dialysis:
Not available (Anastrozole is highly protein bound and not significantly renally cleared)
Hepatic Impairment:
Mild:
No dose adjustment required
Moderate:
No dose adjustment required
Severe:
No dose adjustment required, but caution is advised due to limited data and potential for increased exposure
Confidence:
Medium
Pharmacology
Mechanism of Action
Anastrozole is a potent and highly selective non-steroidal aromatase inhibitor. It inhibits the enzyme aromatase (cytochrome P450 aromatase), which catalyzes the conversion of androgens (androstenedione and testosterone) to estrogens (estrone and estradiol) in peripheral tissues. By significantly lowering circulating estrogen levels, anastrozole deprives estrogen-dependent breast cancer cells of the estrogen required for their growth, leading to tumor regression or inhibition of growth.
Pharmacokinetics
Absorption:
Bioavailability:
Approximately 85%
Tmax:
2-3 hours
FoodEffect:
Food slightly decreases the rate but not the extent of absorption.
Distribution:
Vd:
Approximately 19.2 L
ProteinBinding:
Approximately 40%
CnssPenetration:
Limited
Elimination:
HalfLife:
Approximately 40-50 hours
Clearance:
Approximately 25.5 L/hr
ExcretionRoute:
Primarily renal (approximately 60% as metabolites, 10% as unchanged drug); fecal (approximately 11% as metabolites)
Unchanged:
Approximately 10% (renal)
Pharmacodynamics
OnsetOfAction:
Rapid; significant estrogen suppression within 24 hours
PeakEffect:
Maximum estrogen suppression achieved within 7 days of daily dosing
DurationOfAction:
Sustained estrogen suppression due to long half-life
Confidence:
Medium
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 or seek medical attention immediately:
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 attention 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 or any other symptoms that bother you or do not go away, contact your doctor or seek medical help:
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 about side effects, consult 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 or seek medical attention immediately:
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 attention 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 or any other symptoms that bother you or do not go away, contact your doctor or seek medical help:
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 about side effects, consult 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 pain/swelling in one leg (signs of blood clot)
- Yellowing of skin or eyes, dark urine, severe nausea/vomiting, or unusual tiredness (signs of liver problems)
- Severe or persistent joint pain that interferes with daily activities
- Unusual vaginal bleeding
- New or worsening bone pain
- Signs of an allergic reaction (rash, itching, swelling, severe dizziness, trouble breathing)
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 or plan to breastfeed. 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 and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications 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 or plan to breastfeed. 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 and over-the-counter drugs, natural products, and vitamins, with your doctor and pharmacist. They will help determine if it is safe to take this medication with your other medications 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, resulting in thinner and weaker bones. This may increase your 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, resulting in thinner and weaker bones. This may increase your 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 may include exaggeration of known side effects (e.g., severe hot flashes, joint pain, gastrointestinal upset).
What to Do:
Seek immediate medical attention. Call 911 or Poison Control at 1-800-222-1222. Treatment is supportive and symptomatic.
Drug Interactions
Contraindicated Interactions
- Estrogen-containing therapies (e.g., hormone replacement therapy, oral contraceptives): May counteract the pharmacologic action of anastrozole.
Major Interactions
- Tamoxifen: Co-administration with tamoxifen significantly reduces anastrozole plasma concentrations. Should not be co-administered.
Moderate Interactions
- Estrogen-containing products (e.g., vaginal creams, patches): May reduce efficacy.
- CYP3A4 inducers/inhibitors: While anastrozole is metabolized by CYP3A4, significant clinical interactions are not expected due to its multiple metabolic pathways and high therapeutic index.
Confidence Interactions
Monitoring
Baseline Monitoring
Bone Mineral Density (BMD)
Rationale: Anastrozole can cause bone loss and increase fracture risk due to estrogen suppression.
Timing: Before initiating therapy
Lipid Profile (Cholesterol, Triglycerides)
Rationale: May cause increases in total cholesterol and LDL cholesterol.
Timing: Before initiating therapy
Liver Function Tests (LFTs)
Rationale: To assess baseline hepatic function, especially in patients with pre-existing impairment.
Timing: Before initiating therapy
Menopausal Status Confirmation
Rationale: Anastrozole is indicated for postmenopausal women; confirmation is crucial.
Timing: Before initiating therapy
Routine Monitoring
Bone Mineral Density (BMD)
Frequency: Every 1-2 years or as clinically indicated
Target: Maintain T-score > -2.5
Action Threshold: Consider bisphosphonates or other bone-sparing agents if significant bone loss or fracture occurs.
Lipid Profile
Frequency: Annually or as clinically indicated
Target: Within normal limits or individualized targets
Action Threshold: Consider lifestyle modifications or lipid-lowering agents if levels are elevated.
Liver Function Tests (LFTs)
Frequency: Periodically, or if symptoms of hepatic dysfunction develop
Target: Within normal limits
Action Threshold: Investigate significant elevations; consider dose adjustment or discontinuation if severe.
Vitamin D levels
Frequency: Periodically
Target: Sufficient levels
Action Threshold: Supplement if deficient.
Symptom Monitoring
- Hot flashes
- Arthralgia (joint pain)
- Fatigue
- Vaginal dryness
- Mood disturbances (depression, anxiety)
- Nausea
- Headache
- Hair thinning
- Peripheral edema
- Signs of thromboembolic events (e.g., leg pain, swelling, shortness of breath, chest pain)
- Signs of liver dysfunction (e.g., jaundice, dark urine, persistent nausea/vomiting)
Special Patient Groups
Pregnancy
Contraindicated in pregnancy. Anastrozole 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
Contraindicated during lactation. It is not known whether anastrozole is excreted in human milk. Due to the potential for serious adverse reactions in breastfed infants, a decision should be made whether to discontinue nursing or to discontinue the drug, taking into account the importance of the drug to the mother.
Infant Risk:
High risk (L5 - Contraindicated)
Pediatric Use
Anastrozole is not indicated for use in pediatric patients. Its safety and efficacy have not been established in this population. Use in children with precocious puberty or gynecomastia is investigational and not FDA-approved.
Geriatric Use
No specific dose adjustment is required based on age. However, elderly patients may have a higher incidence of certain adverse events (e.g., bone fractures, cardiovascular events) and should be monitored closely for age-related comorbidities and side effects.
Clinical Information
Clinical Pearls
- Anastrozole is a first-line endocrine therapy for hormone receptor-positive breast cancer in postmenopausal women.
- It is generally well-tolerated, but common side effects include arthralgia, hot flashes, and fatigue.
- Bone health monitoring (DEXA scans) and management (calcium, vitamin D, bisphosphonates if needed) are crucial due to increased risk of bone loss and fractures.
- Patients should be advised to report any signs of thromboembolic events immediately.
- Compliance is key for long-term efficacy in the adjuvant setting (typically 5 years).
- Unlike tamoxifen, anastrozole does not increase the risk of endometrial cancer or DVT/PE as significantly, but it does increase the risk of musculoskeletal events and fractures.
Alternative Therapies
- Letrozole (another non-steroidal aromatase inhibitor)
- Exemestane (a steroidal aromatase inactivator)
- Tamoxifen (a selective estrogen receptor modulator - SERM)
- Fulvestrant (an estrogen receptor downregulator)
Cost & Coverage
Average Cost:
$100 - $500 per 30 tablets (generic)
Generic Available:
Yes
Insurance Coverage:
Tier 1 or Tier 2 for generic; Tier 3 or higher for brand, depending on formulary.
General Drug Facts
If your symptoms or health issues persist or worsen, it is 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 it's a good idea to check with your pharmacist for more information. If you have any questions or concerns about your 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 emergency medical attention. When seeking help, be prepared to provide details about the medication taken, the amount, and the time it happened.