Anastrol
Generic Name
Anastrozole
Manufacturer
Various generic manufacturers (e.g., Square Pharmaceuticals Ltd. in Bangladesh)
Country
Global
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Description
Overview of the medicine
Anastrozole is a non-steroidal aromatase inhibitor used in the treatment of breast cancer in postmenopausal women. It works by reducing the amount of estrogen the body makes, which can promote the growth of some types of breast cancer.
Uses & Indications
Dosage
Adults
The recommended dose is one 1 mg tablet taken orally once daily.
Elderly
No dose adjustment is generally required for elderly patients.
Renal_impairment
No dose adjustment is generally required for patients with mild to moderate renal impairment. Use with caution in patients with severe renal impairment due to limited data.
How to Take
Take orally, with or without food, at approximately the same time each day. Swallow the tablet whole with water.
Mechanism of Action
Anastrozole is a potent and highly selective non-steroidal aromatase inhibitor. It works by competitively binding to the aromatase enzyme, thereby inhibiting the conversion of androgens (like androstenedione and testosterone) to estrogens (estrone and estradiol) in peripheral tissues. This leads to a significant reduction in circulating estrogen levels, which is crucial for treating hormone receptor-positive breast cancer.
Pharmacokinetics
Onset
Estrogen suppression observed within 24 hours of the first dose.
Excretion
Approximately 11% of the dose is excreted unchanged in the urine; metabolites are primarily excreted in the urine and feces.
Half life
Approximately 40-50 hours.
Absorption
Rapidly absorbed from the gastrointestinal tract; peak plasma concentrations are usually reached within 2 hours.
Metabolism
Extensively metabolized by the liver, primarily via N-dealkylation, hydroxylation, and glucuronidation. The main metabolite, triazole, is inactive.
Side Effects
Contraindications
- Pregnancy and lactation.
- Premenopausal women.
- Known hypersensitivity to anastrozole or any component of the formulation.
- Patients with severe hepatic impairment (limited data).
Drug Interactions
Tamoxifen
Co-administration with tamoxifen should be avoided as it may reduce anastrozole's plasma concentration and efficacy.
Estrogen-containing therapies
Should not be co-administered with estrogen-containing therapies (e.g., hormone replacement therapy) as they would negate the pharmacological action of anastrozole.
Coadministration with CYP3A4 inhibitors/inducers
Anastrozole is primarily metabolized by CYP3A4, so coadministration with potent inhibitors (e.g., ketoconazole) or inducers (e.g., rifampicin) may alter anastrozole plasma levels, although significant clinical impact is generally not expected.
Storage
Store below 30°C (86°F) in a dry place, protected from light and moisture. Keep out of reach and sight of children.
Overdose
There is no specific antidote for anastrozole overdose. Treatment of overdose should be symptomatic and supportive. Since anastrozole is highly protein bound, dialysis may not be helpful in an overdose situation.
Pregnancy & Lactation
Anastrozole is contraindicated in pregnant women due to potential fetal harm and in lactating women due to unknown excretion into human milk and potential for serious adverse reactions in nursing infants. Premenopausal women should use effective non-hormonal contraception.
Side Effects
Contraindications
- Pregnancy and lactation.
- Premenopausal women.
- Known hypersensitivity to anastrozole or any component of the formulation.
- Patients with severe hepatic impairment (limited data).
Drug Interactions
Tamoxifen
Co-administration with tamoxifen should be avoided as it may reduce anastrozole's plasma concentration and efficacy.
Estrogen-containing therapies
Should not be co-administered with estrogen-containing therapies (e.g., hormone replacement therapy) as they would negate the pharmacological action of anastrozole.
Coadministration with CYP3A4 inhibitors/inducers
Anastrozole is primarily metabolized by CYP3A4, so coadministration with potent inhibitors (e.g., ketoconazole) or inducers (e.g., rifampicin) may alter anastrozole plasma levels, although significant clinical impact is generally not expected.
Storage
Store below 30°C (86°F) in a dry place, protected from light and moisture. Keep out of reach and sight of children.
Overdose
There is no specific antidote for anastrozole overdose. Treatment of overdose should be symptomatic and supportive. Since anastrozole is highly protein bound, dialysis may not be helpful in an overdose situation.
Pregnancy & Lactation
Anastrozole is contraindicated in pregnant women due to potential fetal harm and in lactating women due to unknown excretion into human milk and potential for serious adverse reactions in nursing infants. Premenopausal women should use effective non-hormonal contraception.
Frequently Asked Questions
Common questions about this medicine
Pack Sizes
Shelf Life
Typically 2-3 years, refer to the expiry date on the product packaging.
Availability
Pharmacies, Hospitals
Approval Status
FDA approved
Patent Status
Generic versions available (original patent expired)
Clinical Trials
Key clinical trials such as ATAC (Arimidex, Tamoxifen, Alone or in Combination) trial and ARNO 95 study have demonstrated the efficacy and safety of anastrozole in both early and advanced breast cancer in postmenopausal women. These trials showed superior efficacy over tamoxifen in certain settings and a manageable side effect profile.
Lab Monitoring
- Bone mineral density (BMD) monitoring (before treatment and periodically during treatment due to risk of osteoporosis).
- Lipid profile (due to potential for hypercholesterolemia).
- Liver function tests (periodically).
Doctor Notes
- Prior to initiating anastrozole, assess bone mineral density (BMD) and periodically monitor during treatment due to the risk of osteoporosis. Consider calcium and vitamin D supplementation.
- Evaluate cardiovascular risk factors before and during treatment.
- Counsel patients on potential menopausal-like symptoms (e.g., hot flashes, arthralgia) and strategies for management.
- Anastrozole is not indicated for premenopausal women; ensure menopausal status confirmation prior to therapy.
Patient Guidelines
- Take anastrozole exactly as prescribed by your doctor, usually once a day.
- Do not stop taking the medicine without consulting your doctor, even if you feel well.
- Report any new or worsening symptoms, especially bone pain, hot flashes, or unusual vaginal bleeding, to your doctor immediately.
Missed Dose Advice
If a dose is missed, take it as soon as you remember. If it is almost time for your next dose (e.g., within 12 hours of the next dose), skip the missed dose and resume your regular dosing schedule. Do not take two doses at once to make up for a missed one.
Driving Precautions
Anastrozole may cause drowsiness, dizziness, or asthenia. If you experience these effects, avoid driving or operating machinery until you know how the medicine affects you.
Lifestyle Advice
- Maintain a healthy diet rich in calcium and vitamin D, and engage in regular weight-bearing exercise to support bone health and manage weight, as anastrozole can increase the risk of osteoporosis.
- Discuss with your doctor about potential calcium and vitamin D supplementation to mitigate bone loss.
- Manage hot flashes through lifestyle adjustments like dressing in layers, avoiding triggers, and staying cool.
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Global Brand Names
International brand names for this medicine. Click a brand to search for detailed information.
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