Description

Technical Parameters

Introduction

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Products Description

### Systematic introduction of Letrozole Raws Powder

Letrozole is a highly effective non-steroidal aromatase inhibitor, widely used in the clinical treatment of breast cancer. As a representative drug of the third-generation aromatase inhibitor, its raw material (Letrozole Raws Powder) plays an important role in the pharmaceutical field. This article will systematically explain the key information of Letrozole raw materials from the aspects of chemical properties, pharmacological effects, production process, application field, quality control, market status and safety.

### 1. Chemical properties and basic information

#### 1. Chemical name and structure

- **Chemical name**: 4,4'-(1H-1,2,4-triazole-1-ylmethylene) dibenzonitrile

- **Molecular formula**: C17H11N5

- **Molecular weight**: 285.31 g/mol

- **CAS number**: 112809-51-5

- **Structural formula**: 1,2,4-triazole ring as the core, two para-cyanophenyl groups connected by methylene. The presence of the triazole ring is the key structural feature of its high selectivity.

#### 2. Physical properties

- **Appearance**: White to off-white crystalline powder

- **Melting point**: About 181-184℃

- **Solubility**: Soluble in organic solvents (such as methanol, ethanol), slightly soluble in water (about 0.1 mg/mL at pH 7).

- **Stability**: Stable under dry and dark conditions, but sensitive to strong acids and strong oxidants.

#### 3. Chemical properties

- **Acid-base properties**: Weakly alkaline (nitrogen atoms in the triazole ring can bind protons).

- **Reactivity**: The cyanophenyl structure gives it electrophilicity and may participate in condensation or cyclization reactions.

- **Synthetic intermediates**: Commonly used intermediates include 4-bromomethylbenzonitrile and 1H-1,2,4-triazole sodium salt.

### 2. Pharmacological properties and clinical advantages

#### 1. Mechanism of action

- **Aromatase inhibition**: By competitively binding to the heme group of cytochrome P450, it irreversibly inhibits aromatase activity and blocks the conversion of androgens (such as androstenedione) to estrogens (estrone, estradiol).

- **Selectivity**: No significant effect on the synthesis of adrenal cortical hormones, reducing side effects.

#### 2. Pharmacokinetics

- **Absorption**: Oral bioavailability is 99.9%, and food has no significant effect on absorption.

- **Distribution**: Plasma protein binding rate is about 60%, and it is widely distributed in tissues.

- **Metabolism**: Mainly metabolized to inactive carboxylic acid metabolites by liver CYP3A4/CYP2A6.

- **Half-life**: About 2 days, supporting once-daily dosing.

#### 3. Clinical advantages

- **High efficiency**: For postmenopausal breast cancer patients, it can reduce estrogen levels by 97-99%.

- **Low cross-resistance**: No cross-resistance with tamoxifen, suitable for second-line treatment.

- **Tolerance**: Compared with traditional chemotherapy drugs, adverse reactions (such as hot flashes and bone pain) are milder.

### 3. Production process and technological innovation

#### 1. Synthesis route

- **Classic route**:

1. Condensation of 4-bromomethylbenzonitrile and 1H-1,2,4-triazole sodium salt in a polar solvent (such as DMF).

2. Purification of intermediates (crystallization or column chromatography).

3. Drying and crushing of the final product.

- **Yield optimization**: Increase the reaction efficiency to more than 85% through catalysts (such as phase transfer catalysts).

#### 2. Process challenges

- **Impurity control**: It is necessary to monitor by-products (such as double substitution products) and residual solvents (DMF, THF).

- **Green chemistry improvement**: Use aqueous phase reaction or microwave-assisted synthesis to reduce the use of organic solvents.

#### 3. Crystallization process

- **Polymorphism research**: There are two crystal forms (type I is stable, type II is metastable), and high-purity type I crystals need to be obtained through solvent regulation (such as ethanol/water system).

### 4. Application fields and indications

#### 1. Breast cancer treatment

- **Adjuvant therapy**: used for postmenopausal hormone receptor-positive breast cancer surgery to reduce the recurrence rate (5-year survival rate increased by 15%).

- **Metastatic breast cancer**: The median progression-free survival of first-line treatment is 10-12 months.

#### 2. Other potential applications

- **Infertility**: Low doses are used to induce ovulation (off-label use, controversial).

- **Estrogen-dependent disease research**: such as clinical trials of endometriosis and uterine fibroids.

### 5. Quality control and standards

#### 1. Detection method

- **HPLC method**: C18 column, mobile phase is acetonitrile-phosphate buffer, detection wavelength is 240 nm.

- **Impurity spectrum analysis**: must meet ICH Q3A standards, total impurities ≤0.5%.

- **Chiral purity**: ensure that there are no enantiomers (no chiral center is involved in the synthesis route).

#### 2. Stability study

- **Accelerated test**: 6 months at 40℃/75% RH, content change must be ≤2%.

- **Long-term storage**: It is recommended to store below 25℃ away from light, with a shelf life of 3 years.

### 6. Market status and competition landscape

#### 1. Market size

- **Global demand**: The market size in 2023 is about US$850 million, with an annual growth rate of 6%.

- **Regional distribution**: North America accounts for 45%, Europe 30%, and the Asia-Pacific region is growing rapidly (China accounts for 50% of the Asia-Pacific share).

#### 2. Major manufacturers

- **Original manufacturer**: Novartis (trade name Femara), the patent has expired.

- **Generic drug companies**: India's Sun Pharma, China's Hengrui Medicine, Hisun Pharmaceutical, etc.

#### 3. Price trend

- **Price of API**: The average price in 2023 is about $2500/kg, a 20% decrease from 2019 (due to competition from generic drugs).

### 7. Safety and regulatory requirements

#### 1. Toxicological data

- **Acute toxicity**: Oral LD50 in rats>2000 mg/kg (low acute toxicity).

- **Long-term toxicity**: Animal experiments show that high doses may cause elevated liver enzymes.

#### 2. Side effect management

- **Common adverse reactions**: Hot flashes (30%), joint pain (25%).

- **Serious risks**: Osteoporosis (calcium and vitamin D supplementation are required).

#### 3. Regulatory compliance

- **GMP certification**: Must comply with FDA 21 CFR Part 211 or EU GMP Annex 2.

- **Environmental requirements**: Cyanide produced during synthesis must be strictly handled (such as sodium hypochlorite oxidation).

### 8. Future development and research directions

1. **Development of new formulations**: such as long-acting injections and transdermal patches to improve patient compliance.

2. **Exploration of combined therapy**: Combined with CDK4/6 inhibitors (such as palbociclib) to enhance efficacy.

3. **Application of synthetic biology**: Use engineered strains to biocatalyze the synthesis of intermediates to reduce production costs.

### Summary

Due to its high efficiency, selectivity and mature synthesis process, letrozole API has become one of the core drugs for breast cancer treatment. With the optimization of production processes and the expansion of new indications, its position in the global pharmaceutical market will continue to consolidate. In the future, the combined application of green synthesis technology and precision medicine may further promote its development.