Arimidex (anastrozole) represents a cornerstone in endocrine therapy for hormone receptor-positive breast cancer in postmenopausal women. As a third-generation nonsteroidal aromatase inhibitor, it operates through highly selective enzyme suppression, fundamentally altering the hormonal environment that fuels cancer proliferation. This targeted mechanism offers a sophisticated therapeutic approach with a well-established efficacy and safety profile, making it a first-line option in adjuvant and advanced treatment settings. Clinical evidence consistently demonstrates its superiority over previous standard therapies in reducing recurrence risk and improving disease-free survival outcomes.

Features

• Contains 1 mg of anastrozole per tablet
• Nonsteroidal aromatase inhibitor classification
• High specificity for cytochrome P450 aromatase enzyme
• Once-daily oral administration regimen
• Available in blister packs of 28 tablets
• Bioavailability of approximately 80% following oral administration
• Mean elimination half-life of 50 hours in postmenopausal women
• Hepatic metabolism via N-dealkylation, hydroxylation, and glucuronidation

Benefits

• Significantly reduces estrogen production by inhibiting aromatase conversion of androgens to estrogens
• Demonstrates superior disease-free survival compared to tamoxifen in multiple clinical trials
• Lower incidence of thromboembolic events and endometrial cancer compared to selective estrogen receptor modulators
• Maintains bone mineral density through complementary management strategies
• Improves overall survival rates in advanced hormone receptor-positive breast cancer
• Offers convenient once-daily dosing that supports long-term treatment adherence

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 postmenopausal women with hormone receptor-positive or hormone receptor unknown locally advanced or metastatic breast cancer. Additionally, it is used for the 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 for up to 5 years.

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 drug levels. Tablets should be swallowed whole with water and not crushed or chewed. Dosage adjustment is not necessary for patients with mild to moderate hepatic impairment or renal impairment. No initial dosage adjustment is recommended for elderly patients.

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 anastrozole has shown favorable hepatic safety profile. Patients with pre-existing ischemic heart disease should be closely monitored. Caution is advised when prescribing to patients with moderate to severe hepatic impairment. Driving or operating machinery may be affected by fatigue and dizziness reported by some patients.

Contraindications

Arimidex is contraindicated in women with known hypersensitivity to anastrozole or any components of the formulation. It must not be used in premenopausal women, pregnant women, or during lactation. The medication is contraindicated in patients with severe hepatic impairment (Child-Pugh class C). Concomitant use with estrogen-containing therapies is contraindicated as these agents would negate the pharmacological effects of anastrozole. Patients with genetically confirmed estrogen receptor-negative breast cancer should not receive this medication.

Possible side effects

The most frequently reported adverse reactions include hot flashes (35%), asthenia (16%), arthritis (15%), arthralgia (14%), pain (11%), and pharyngitis (10%). Less common but clinically significant effects may include mood disturbances (9%), nausea (9%), osteoporosis (11% at 5 years), fractures (10% at 5 years), and carpal tunnel syndrome (3%). Cardiovascular events such as angina pectoris (2%) and myocardial infarction (1%) have been reported. Laboratory abnormalities may include elevated gamma-glutamyl transferase (5%) and cholesterol levels (9%). Most adverse events are mild to moderate in severity and often diminish with continued therapy.

Drug interaction

Arimidex demonstrates minimal metabolic drug interactions due to its lack of inhibition of major cytochrome P450 enzymes. However, concomitant use with tamoxifen should be avoided as it reduces anastrozole plasma concentrations by 27%. Estrogen-containing therapies may diminish the pharmacological effect of anastrozole. Although formal interaction studies are limited, caution is advised with drugs that induce CYP3A4 and CYP2C8. No clinically significant interactions have been observed with warfarin, cimetidine, or other commonly co-administered medications. Healthcare providers should monitor for potential interactions with highly protein-bound drugs.

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 never take two doses simultaneously to make up for a missed dose. Maintaining consistent dosing is important for optimal estrogen suppression, but occasional missed doses are unlikely to significantly impact overall treatment efficacy. Patients should inform their healthcare provider if multiple doses are missed or if adherence becomes problematic.

Overdose

There is no specific antidote for Arimidex overdose. Single doses of up to 60 mg have been administered without serious adverse effects. Expected manifestations of overdose would likely include enhanced pharmacological effects such as greater estrogen suppression. Management should involve supportive care and symptomatic treatment. Gastric lavage may be considered if ingestion occurred within a short time frame. Vital signs should be monitored regularly, and appropriate medical supervision maintained until the patient’s condition stabilizes. Dialysis is unlikely to be beneficial due to high protein binding.

Storage

Store Arimidex tablets at room temperature between 15°C and 30°C (59°F and 86°F) in the original container. Protect from light and moisture by keeping the bottle tightly closed. Keep out of reach of children and pets. Do not store in bathroom cabinets where humidity levels may fluctuate. Discard any medication that has passed the expiration date printed on the packaging. Proper disposal should follow local regulations for pharmaceutical waste, typically through medication take-back programs rather than flushing or household trash.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Treatment decisions must be made by qualified healthcare professionals based on individual patient characteristics and comprehensive clinical assessment. The prescribing physician should be consulted for specific dosage recommendations and treatment duration. Actual clinical effects may vary among patients. This information does not cover all possible uses, directions, precautions, or adverse effects. Patients should report any unexpected symptoms or side effects to their healthcare provider immediately.

Reviews

Clinical studies demonstrate Arimidex’s consistent efficacy profile with a 2.8% absolute improvement in disease-free survival compared to tamoxifen at 5 years. The ATAC trial, involving 9,366 patients, showed a 24% reduction in recurrence risk. Long-term follow-up data confirms maintained superiority with 15-year disease-free survival rates of 53.3% versus 47.5% for tamoxifen. Quality of life studies indicate generally favorable tolerability, though musculoskeletal symptoms remain a treatment challenge for some patients. Real-world evidence supports the clinical trial findings, with adherence rates exceeding 80% in most observational studies. Healthcare providers consistently rate Arimidex as a fundamental component of modern endocrine therapy strategies.