Aribex

• Approved Indications:
• Treatment of hormone receptor-positive (HR+) breast cancer in postmenopausal women.
• Adjuvant therapy for early-stage breast cancer after surgery.
• Treatment of advanced or metastatic breast cancer in postmenopausal women.
• First-line treatment for hormone receptor-positive advanced breast cancer.
• Off-label/Clinically Accepted Uses:
• Use in male breast cancer (limited data).
• Prevention of breast cancer in high-risk postmenopausal women (select cases).

• Route: Oral.
• Adults:
• Standard dose: 1 mg once daily, with or without food.
• Pediatrics: Not established.
• Elderly: No dosage adjustment required.
• Renal Impairment: No adjustment generally required for mild to moderate impairment; data limited in severe impairment, use with caution.
• Hepatic Impairment: Use with caution in severe hepatic impairment; no dose adjustment for mild to moderate.
• Duration: Typically administered for 5 years in adjuvant settings; duration may vary based on clinical response and guidelines.

Anastrozole is a non-steroidal aromatase inhibitor that selectively inhibits the aromatase enzyme responsible for the peripheral conversion of androgens to estrogens. By reducing estrogen production, it lowers circulating estrogen levels, depriving estrogen receptor-positive breast cancer cells of their growth stimulus, thereby inhibiting tumor growth and progression.

• Absorption: Well absorbed orally, peak plasma concentration reached within 2 hours.
• Bioavailability: Approximately 83%.
• Distribution: Widely distributed; plasma protein binding about 40%.
• Metabolism: Primarily hepatic via N-dealkylation, hydroxylation, and glucuronidation (CYP3A4 involvement).
• Half-life: Approximately 50 hours, allowing once-daily dosing.
• Elimination: Excreted mainly in urine (about 85%), with a small amount in feces.

• Pregnancy: FDA Category D — contraindicated during pregnancy due to potential fetal harm. Women of childbearing potential should use effective contraception.
• Lactation: Unknown if excreted in human milk; breastfeeding not recommended during treatment due to potential for serious adverse effects in the infant.

• Aromatase inhibitor, Antineoplastic agent.

• Known hypersensitivity to anastrozole or any component of the formulation.
• Pregnancy and breastfeeding.
• Severe hepatic impairment (relative contraindication; caution advised).

• Monitor bone mineral density; prolonged use may increase risk of osteoporosis and fractures.
• Caution in patients with pre-existing hepatic impairment.
• Monitor lipid profiles periodically; dyslipidemia may occur.
• May cause menopausal symptoms such as hot flashes, mood changes.
• Early signs of severe adverse events such as allergic reactions, liver dysfunction require prompt medical attention.

• Common: Hot flashes, arthralgia, fatigue, nausea, headache, edema, hypertension.
• Serious (rare): Osteoporosis, fractures, hypersensitivity reactions, hepatic dysfunction.
• Onset: Usually within weeks to months; dose-dependent severity possible.

• CYP3A4 inducers (e.g., rifampin) may reduce anastrozole plasma levels, potentially reducing efficacy.
• No significant interactions with tamoxifen, but combination is generally avoided as tamoxifen can reduce anastrozole effectiveness.
• Hormone replacement therapy or estrogen-containing products reduce anastrozole effectiveness.
• Caution with drugs affecting liver enzymes.

• Guidelines recommend anastrozole as a first-line adjuvant therapy in postmenopausal women with HR+ breast cancer.
• Extended use beyond 5 years is under evaluation based on individual risk-benefit assessment.
• Recent studies support anastrozole use for breast cancer prevention in high-risk women.

• Store at 20°C to 25°C (68°F to 77°F).
• Protect from moisture and light.
• Keep out of reach of children.
• Do not freeze.