Femara (letrozole) is a potent, third-generation aromatase inhibitor indicated for the adjuvant treatment of postmenopausal women with hormone receptor-positive early breast cancer. It is also approved for the extended adjuvant treatment of early breast cancer following five years of tamoxifen therapy, as well as for the first-line treatment of advanced or metastatic breast cancer in postmenopausal women. By selectively inhibiting the aromatase enzyme, Femara dramatically reduces estrogen production, depriving hormone-sensitive tumor cells of the fuel required for proliferation. Its targeted mechanism offers a sophisticated endocrine therapy option with a well-established efficacy and safety profile, making it a cornerstone in the management of hormone-dependent breast malignancies.

Features

• Active ingredient: Letrozole 2.5 mg
• Pharmacologic class: Nonsteroidal aromatase inhibitor
• Administration: Oral tablet
• Bioavailability: 99.9% with rapid and complete absorption
• Half-life: Approximately 2 days
• Metabolism: Hepatic, via CYP2A6 and CYP3A4
• Excretion: Primarily renal as inactive metabolites
• FDA-approved for multiple breast cancer indications

Benefits

• Significantly reduces the risk of cancer recurrence in early breast cancer
• Improves disease-free survival and overall survival rates
• Effective extended adjuvant therapy after tamoxifen treatment
• Superior efficacy compared to tamoxifen in advanced settings
• Generally well-tolerated with manageable side effect profile
• Convenient once-daily dosing regimen

Common use

Femara is primarily prescribed for the adjuvant treatment of hormone receptor-positive early breast cancer in postmenopausal women. It is also utilized as extended adjuvant therapy following 5 years of tamoxifen treatment to further reduce recurrence risk. In advanced or metastatic breast cancer, Femara serves as first-line endocrine therapy. Additionally, it is sometimes used off-label for ovulation induction in fertility treatments due to its estrogen-suppressing properties, though this application requires careful medical supervision.

Dosage and direction

The recommended dosage of Femara is 2.5 mg administered orally once daily, with or without food. Treatment duration varies based on indication: adjuvant therapy typically continues for 5 years, while extended adjuvant treatment may continue for up to 5 additional years following tamoxifen. For advanced breast cancer, treatment continues until disease progression or unacceptable toxicity. Tablets should be swallowed whole with water; crushing or chewing should be avoided. Dosage adjustment is generally not required for elderly patients but may be necessary in those with severe hepatic impairment.

Precautions

Patients should undergo comprehensive baseline assessment including bone mineral density evaluation due to increased osteoporosis risk. Regular monitoring of lipid profiles is recommended as letrozole may elevate cholesterol levels. Hepatic function should be assessed periodically, particularly in patients with pre-existing liver conditions. Caution is advised in patients with severe renal impairment (CrCl <30 mL/min). Patients should be informed about potential dizziness and advised against driving or operating machinery until they know how Femara affects them. Vitamin D and calcium supplementation is often recommended to mitigate bone density loss.

Contraindications

Femara is contraindicated in premenopausal women, pregnant women, and nursing mothers due to potential fetal harm and interference with estrogen production. It should not be used in patients with known hypersensitivity to letrozole or any component of the formulation. Concomitant use with estrogen-containing therapies is contraindicated as it would counteract Femara’s therapeutic effect. The medication is not indicated for use in pediatric patients and is contraindicated in those with severe hepatic impairment not related to metastasis.

Possible side effect

Common adverse reactions (≥10%) include hot flashes (33%), fatigue (16%), arthralgia (15%), headache (13%), and nausea (12%). Musculoskeletal events such as bone pain and arthritis may occur. Less frequent but clinically significant side effects include osteoporosis (10-15% incidence), hypercholesterolemia (16%), and increased sweating (11%). Serious but rare adverse events include cardiovascular events (myocardial infarction, angina, stroke) occurring in approximately 2-4% of patients and venous thromboembolic events. Most side effects are mild to moderate in severity and often diminish with continued therapy.

Drug interaction

Strong CYP3A4 inducers (rifampicin, carbamazepine, phenytoin) may decrease letrozole concentrations, potentially reducing efficacy. CYP2A6 inhibitors may increase letrozole exposure. Tamoxifen co-administration reduces letrozole plasma concentrations by 38% and is not recommended. Estrogen-containing therapies antagonize Femara’s therapeutic effect and should be avoided. No clinically significant interactions have been observed with warfarin, though monitoring is prudent. Caution is advised with medications that prolong QT interval, though letrozole itself has minimal effect on cardiac repolarization.

Missed dose

If a dose is missed, it should be taken 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 one. Consistent daily administration is important for maintaining stable drug levels and optimal efficacy. Healthcare providers should be consulted if multiple doses are missed or if the patient is uncertain about how to proceed.

Overdose

No specific antidote for letrozole overdose exists. Single doses up to 62.5 mg have been administered without severe adverse effects. Expected manifestations of significant overdose would likely include exaggerated pharmacological effects: severe dizziness, headache, nausea, and vomiting. Management should be supportive and symptomatic, including gastric lavage if ingestion was recent. Vital signs should be monitored, and appropriate symptomatic treatment initiated. Dialysis is unlikely to be beneficial due to high protein binding and extensive tissue distribution.

Storage

Store Femara tablets at room temperature (20-25°C or 68-77°F) in their original container. Protect from light and moisture. Keep the bottle tightly closed and out of reach of children and pets. Do not store in bathroom cabinets where humidity levels fluctuate. Discard any medication that has expired or shows signs of deterioration. Proper disposal methods should be followed, preferably through medication take-back programs, to prevent environmental contamination and accidental ingestion.

Disclaimer

This information is provided for educational purposes only and does not constitute medical advice. Treatment decisions should be made exclusively by qualified healthcare professionals based on individual patient characteristics. Always consult with a physician before starting or changing any medication regimen. The prescribing information provided here may not include all possible uses, directions, precautions, or interactions. Full prescribing information is available in the package insert or from the manufacturer.

Reviews

Clinical trials demonstrate Femara’s significant efficacy in breast cancer treatment. The BIG 1-98 trial showed a 21% reduction in disease-free survival events compared to tamoxifen. MA-17 trial confirmed a 42% reduction in recurrence risk with extended adjuvant therapy. Patients report generally good tolerability, though some note challenging side effects including joint pain and hot flashes. Oncology specialists consistently rate Femara as a first-choice aromatase inhibitor due to its proven efficacy profile and manageable toxicity spectrum. Long-term follow-up data continues to support its role in standard breast cancer care protocols.