Arimidex (anastrozole) represents a significant advancement in hormonal therapy for postmenopausal women with hormone receptor-positive breast cancer. As a third-generation aromatase inhibitor, it offers targeted estrogen suppression through a well-tolerated oral formulation. This medication has demonstrated superior efficacy compared to traditional anti-estrogen therapies in multiple clinical trials, establishing itself as a cornerstone in both adjuvant and metastatic treatment settings. Its selective mechanism of action provides precise endocrine manipulation while minimizing impact on other steroidogenic pathways.

Features

• Contains 1 mg anastrozole per tablet
• Non-steroidal aromatase inhibitor classification
• High specificity for aromatase enzyme inhibition
• Oral administration with once-daily dosing
• Bioavailability of approximately 80% when taken fasting
• Plasma half-life of approximately 50 hours in postmenopausal women
• Extensive hepatic metabolism with renal excretion
• Manufactured under current Good Manufacturing Practices (cGMP)

Benefits

• Superior Disease-Free Survival: Demonstrated significant improvement in disease-free survival compared to tamoxifen in multiple large-scale clinical trials
• Reduced Recurrence Risk: Lowers the risk of contralateral breast cancer and distant metastases
• Favorable Safety Profile: Avoids estrogen agonist effects associated with tamoxifen, reducing endometrial cancer risk
• Convenient Dosing: Once-daily oral regimen supports treatment adherence
• Minimal Androgenic Effects: Unlike some hormonal therapies, does not cause masculinizing side effects
• Comprehensive Clinical Evidence: Supported by over two decades of research and real-world experience

Common use

Arimidex is primarily indicated for the adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer. It is also approved for the first-line treatment of hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer in postmenopausal women. Additionally, it is used for treatment of advanced breast cancer in postmenopausal women with disease progression following tamoxifen therapy. The medication may be prescribed as extended adjuvant therapy following initial tamoxifen treatment.

Dosage and direction

The recommended dosage of Arimidex is one 1 mg tablet taken orally once daily, with or without food. For adjuvant treatment, therapy should continue for 5 years unless disease recurrence or unacceptable toxicity occurs. Patients should take the medication at approximately the same time each day to maintain consistent plasma concentrations. Tablets should be swallowed whole with water and not crushed or chewed. No dosage adjustment is necessary for elderly patients or those with mild to moderate hepatic impairment or renal impairment.

Precautions

Patients should undergo comprehensive bone mineral density assessment before initiating therapy and at regular intervals during treatment due to the increased risk of osteoporosis. Regular monitoring of lipid profiles is recommended as aromatase inhibitors may alter lipid metabolism. Hepatic function should be assessed periodically, although no dosage adjustment is required for mild to moderate impairment. Patients with pre-existing ischemic heart disease should be closely monitored. Caution is advised in patients with known hypersensitivity to anastrozole or any excipients in the formulation.

Contraindications

Arimidex is contraindicated in premenopausal women, pregnant women, and nursing mothers due to the potential for fetal harm and interference with estrogen synthesis. It should not be used in patients with demonstrated hypersensitivity to anastrozole or any component of the formulation. Concomitant use with estrogen-containing therapies is contraindicated as it would oppose the pharmacological action of anastrozole. The medication is not indicated for use in pediatric patients.

Possible side effects

The most frequently reported adverse reactions include hot flashes (35%), asthenia (16%), arthritis (17%), arthralgia (15%), pain (14%), hypertension (13%), depression (13%), nausea (11%), headache (10%), and osteoporosis (10%). Less common but serious side effects may include cardiovascular events such as myocardial ischemia, angina pectoris, and myocardial infarction. Hepatic enzyme elevations have been observed in some patients. Cases of carpal tunnel syndrome and trigger finger have been reported in clinical trials.

Drug interaction

Arimidex may interact with estrogen-containing medications, negating its therapeutic effect. Tamoxifen co-administration reduces anastrozole plasma concentrations by approximately 27% and should be avoided. Although formal interaction studies are limited, medications that induce cytochrome P450 3A4 may potentially decrease anastrozole concentrations. No clinically significant interactions have been observed with warfarin or other commonly co-administered medications in clinical trials.

Missed dose

If a dose is missed, patients should take it as soon as remembered unless it is nearly time for the next scheduled dose. In that case, the missed dose should be skipped and the regular dosing schedule resumed. Patients should not double the dose to make up for a missed dose. Consistent daily administration is important for maintaining therapeutic efficacy, so patients should establish routines to support adherence.

Overdose

Limited information is available regarding acute overdose with anastrozole. Single doses of up to 60 mg have been administered without serious adverse effects. In case of suspected overdose, supportive care is recommended with attention to possible estrogen-deficient effects. Gastric lavage may be considered if performed soon after ingestion. Dialysis is unlikely to be beneficial due to high protein binding. Medical toxicology consultation is advised for significant overdoses.

Storage

Store at room temperature between 20°C to 25°C (68°F to 77°F) with excursions permitted between 15°C to 30°C (59°F to 86°F). Keep in the original container with the lid tightly closed to protect from moisture and light. Keep out of reach of children and pets. Do not use after the expiration date printed on the packaging. Properly dispose of any unused medication through medication take-back programs.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Treatment decisions should be made in consultation with a qualified healthcare professional who can consider individual patient factors. The prescribing physician should be familiar with the complete prescribing information and latest clinical data. Patients should report any adverse effects to their healthcare provider promptly.

Reviews

Clinical trials demonstrate Arimidex’s superiority over tamoxifen in reducing recurrence risk with a hazard ratio of 0.87 for disease-free survival. The ATAC trial showed a 24% reduction in recurrence risk compared to tamoxifen after 5 years of treatment. Long-term follow-up data confirm maintained efficacy with manageable side effect profiles. Real-world evidence supports the clinical trial findings, with particular appreciation for its oral administration and generally favorable tolerability compared to other endocrine therapies.