I. Basic Drug Information

Generic Name: Letrozole

Brand Name: Femara

Dosage Form & Strength: 2.5 mg/tablet (film-coated) | 30 tablets/box

Manufacturer: Novartis

Storage: Protect from light; store in a dry place below 30°C; avoid moisture.

Composition:

Active Ingredient: Letrozole (a non-steroidal aromatase inhibitor)

Excipients: Lactose, microcrystalline cellulose, hydroxypropyl methylcellulose, etc. (Contraindicated in patients with lactose intolerance).

II. Indications

Indicated for the following conditions in postmenopausal women:

1. Adjuvant Therapy for Early Breast Cancer:

Post-operative treatment for patients with hormone receptor-positive (ER+/PR+) breast cancer to reduce the risk of recurrence.

2. Extended Adjuvant Therapy:

For patients who have completed 5 years of tamoxifen therapy, continued use of Femara to reduce the risk of recurrence (for up to 4 years).

3. Treatment of Advanced Breast Cancer:

First-line therapy: Locally advanced or metastatic hormone receptor-positive breast cancer;

Second-line therapy: An alternative option following the failure of anti-estrogen therapy (e.g., tamoxifen).

4. Neoadjuvant Therapy:

For hormone receptor-positive, HER-2 negative breast cancer in patients who are not candidates for immediate surgery (treatment duration: 4–8 months).

5. Off-label Use:

Ovulation induction therapy for infertility associated with Polycystic Ovary Syndrome (PCOS) (requires physician assessment). III. Dosage and Administration

Standard Regimen

| Indication | Dosage and Duration | Key Considerations

| All Indications | 2.5 mg orally once daily (may be taken with or without food) | Do not take a missed dose; resume medication according to the original schedule the following day.

| Adjuvant Therapy | Continue for 5 years, or until tumor recurrence | Sequential therapy with Tamoxifen: Letrozole for 2 years + Tamoxifen for 3 years.

| Patients with Hepatic Impairment | Child-Pugh Class C (Severe): 2.5 mg every other day | Mild to Moderate (Child-Pugh A/B): No dosage adjustment required.

| Patients with Renal Impairment | Creatinine clearance ≥ 10 mL/min: No dosage adjustment required | < 10 mL/min: Insufficient data; use with caution.

IV. Adverse Reactions

#Common Adverse Reactions (Incidence ≥ 10%)

The table below summarizes the major reactions and their frequencies by system classification:

| System Classification | Adverse Reaction | Incidence | Severity

| General Disorders | Hot flashes, fatigue, night sweats | 35%-53% | Low

| Musculoskeletal Disorders | Arthralgia/arthritis, bone pain | 25%-36% | Moderate (May lead to discontinuation)

| Metabolic Disorders | Hypercholesterolemia (Lipid monitoring required)| 52% | Moderate

| Gastrointestinal Disorders | Nausea, vomiting, constipation | 11%-20% | Low

| Nervous System Disorders | Headache, dizziness | 4%-18% | Low

Serious Adverse Reactions (Requiring Emergency Management)

1. Skeletal Events:

Osteoporosis (12.2%), fractures (10.4%); the risk increases significantly with long-term use.

2. Cardiovascular Events:

Myocardial infarction (1.0%), stroke (1.5%); particularly in patients with a history of coronary heart disease.

3. Hepatotoxicity:

Elevated transaminases, jaundice (approx. 7%); severe cases may lead to liver failure. 4. Allergic Reactions:

Angioedema, Stevens-Johnson syndrome (rare but potentially fatal).

V. Contraindications

Absolute Contraindications:

1. Hypersensitivity to letrozole or any of its excipients (including lactose);

2. Premenopausal women (may induce ovarian hyperstimulation);

3. Pregnant and breastfeeding women (animal studies have demonstrated embryotoxicity).

Relative Contraindications:

1. Severe hepatic impairment (Child-Pugh Class C);

2. Uncontrolled osteoporosis or high risk of bone fracture.

VI. Precautions

1. Bone Health Management:

Monitor bone mineral density (via DEXA scan) prior to treatment and annually thereafter; supplement with calcium (≥1000 mg/day) and Vitamin D;

Concomitant use of bisphosphonates (e.g., zoledronic acid) may reduce bone loss and the risk of recurrence.

2. Cardiovascular Monitoring:

Perform baseline and periodic assessments of blood lipids and ECGs; seek immediate medical attention if chest pain or dyspnea occurs.

3. Hepatic Function and Drug Interactions:

Avoid concomitant use of strong CYP3A4 inhibitors (e.g., ketoconazole), as this may increase plasma concentrations of letrozole;

Concomitant use of estrogen-containing medications (e.g., oral contraceptives, hormone replacement therapy) is contraindicated, as this may reduce therapeutic efficacy.

4. Special Populations:

Patients with Lactose Intolerance: The excipients contain lactose, which may trigger diarrhea or abdominal bloating;

Athletes: May experience impaired athletic performance due to joint pain.

VII. Pharmacological Mechanism and Efficacy

Mechanism of Action: Potently inhibits aromatase, thereby blocking the conversion of androgens into estrogens and reducing serum estradiol levels by >80%.

Efficacy Data:

Adjuvant Therapy: Reduces the 5-year risk of recurrence by 50% (compared to tamoxifen);

Ovulation Induction: Achieves a live birth rate of 27.5% in patients with PCOS (higher than the 19.5% rate observed with clomiphene). Important Note: Before initiating treatment, confirm menopausal status (FSH > 40 IU/L and Estradiol < 20 pg/mL). The information provided above does not substitute for a medical prescription; specific medication usage must strictly adhere to a physician's instructions, and regular follow-up examinations are required to assess safety.

Product Specifications

Product Name: Novartis Letrozole Tablets 2.5mg * 30 Tablets/Box (Femara Letrozole)

Common Name: Letrozole Tablets

Active Ingredient: Letrozole

Dosage Form: Tablets

Specification: 2.5mg/tablet (Film-coated tablets); 30 tablets/box

Manufacturer: Novartis Pharmaceuticals

Indications: Indicated for postmenopausal women in the following situations:

1. Adjuvant Treatment for Early Breast Cancer:

Post-operative treatment for patients with hormone receptor-positive (ER+/PR+) breast cancer to reduce the risk of recurrence.

2. Extended Adjuvant Treatment:

For patients who have completed 5 years of Tamoxifen therapy, continued use of Femara to reduce the risk of recurrence (for up to 4 years).

3. Treatment of Advanced Breast Cancer:

First-line treatment: Locally advanced or metastatic hormone receptor-positive breast cancer;

Second-line treatment: An alternative option following the failure of anti-estrogen therapy (e.g., Tamoxifen).

4. Neoadjuvant Treatment:

For hormone receptor-positive, HER-2 negative breast cancer in patients who are not suitable for immediate surgery (treatment duration: 4–8 months).

5. Off-label Use:

Ovulation induction therapy for infertility associated with Polycystic Ovary Syndrome (PCOS) (requires physician assessment).

Dosage and Administration: 1. Adjuvant Treatment for Postmenopausal Hormone Receptor-Positive Breast Cancer

Dosage: Oral administration, 2.5mg once daily, for a duration of 5 years or as directed by a physician.

Duration: For post-operative adjuvant treatment, a full course of therapy is generally recommended to minimize the risk of recurrence.

2. First-line or Second-line Treatment for Postmenopausal Advanced Breast Cancer

Dosage: 2.5mg once daily, continued until disease progression occurs or until intolerable adverse reactions develop. 3. Preoperative Neoadjuvant Therapy for Breast Cancer (Selected Regimens)

Dosage: 2.5 mg daily; the duration of treatment is adjusted based on the surgical plan and clinical condition (subject to physician assessment).