[English Name] Fulvestrant Injection

[Active Ingredient] Fulvestrant

[Chemical Name] 7α-[9-(4,4,5,5,5-Pentafluoropentylsulfinyl)nonyl]estra-1,3,5(10)-triene-3,17β-diol

[Molecular Formula] C32H47F5O3S

[Molecular Weight] 606.786

[Description] A white or off-white liquid.

[Indications] Indicated for the treatment of estrogen receptor-positive, locally advanced or metastatic breast cancer in postmenopausal women (including those with natural or surgically induced menopause) who have experienced disease recurrence following or during adjuvant anti-estrogen therapy, or whose disease has progressed during anti-estrogen therapy.

[Dosage and Administration] Administer via intramuscular injection once monthly at a dose of 250 mg. The dose may be administered as a single injection (5 mL) or as two separate injections (2.5 mL each); the injection should be administered slowly.

[Pharmacology and Toxicology] This product is a novel type of estrogen receptor (ER) inhibitor—specifically, an ER downregulator—used for the treatment of breast cancer. Since ERs are found in many breast cancer patients, and the growth of these tumors is stimulated by estrogen, a primary strategy for treating breast cancer currently involves reducing estrogen concentrations. This product binds competitively to ERs with an affinity comparable to that of estradiol. Furthermore, this product blocks ERs, inhibits their binding to estrogen, induces conformational changes in the receptors, and reduces ER concentrations, thereby causing damage to tumor cells. This mechanism of action via ERs is associated with a reduction in Ki67, a marker of cellular proliferation.

Following intravenous administration, this product undergoes rapid and extensive distribution within the body; at steady state, the apparent volume of distribution is approximately 3–5 L/kg, and the drug is cleared rapidly. Following a single intramuscular injection, plasma concentrations of the product reach a peak approximately 7 days post-administration and are sustained for at least one month; the trough concentration is approximately one-third of the peak concentration, and the elimination half-life is approximately 40 days. Following a monthly intramuscular injection of 250 mg of this product, plasma concentrations reach a steady state after approximately 3 to 6 doses. The Area Under the Curve (AUC) following multiple doses is 2.5 times that of a single dose, and the trough concentration following multiple doses is comparable to the peak concentration following a single dose. This product exhibits a high plasma protein binding rate of up to 99%, binding primarily to very-low-density lipoproteins (VLDL), low-density lipoproteins (LDL), and high-density lipoproteins (HDL). After intramuscular or intravenous administration, the product undergoes biotransformation within the body via multiple pathways similar to those of endogenous steroid hormones, including oxidation, aromatization, and hydroxylation. Among the identified metabolites, most are either inactive or possess activity similar to that of the parent compound; excretion occurs primarily via the feces. Renal clearance accounts for less than 1% of elimination, and the primary metabolic enzyme involved is CYP3A4.

【Pharmacokinetics】

【Adverse Reactions】 The most common adverse reactions include gastrointestinal disturbances (nausea, vomiting, constipation, diarrhea, and abdominal pain), headache, back pain, flushing, and pharyngitis. Reactions at the injection site are typically mild and transient, manifesting as pain and inflammation. Other reported dose-related reactions—occurring at an incidence of less than 1%—include thromboembolic events, myalgia, dizziness, and leukopenia. Additionally, during the first 6 weeks of treatment, patients transitioning from prior hormonal therapy to treatment with this product may experience vaginal bleeding.

【Precautions】 (Refer to the full package insert for details)

【Contraindications】 Contraindicated in pregnant women.

Product Specifications

Product Name: FASNORM Fulvestrant Injection (250 mg/5 mL)

Common Name: FASNORM

Active Ingredient: Fulvestrant

Dosage Form: Injection Solution

Specification: 250 mg/5 mL

Manufacturer: Biocon (India)

Indications:Used for the treatment of estrogen receptor-positive, locally advanced or metastatic breast cancer in postmenopausal women (including those with natural or surgically induced menopause) who have experienced disease recurrence following or during adjuvant anti-estrogen therapy, or whose disease has progressed during anti-estrogen therapy. Dosage and Administration: Administer via intramuscular injection once monthly at a dose of 250 mg. The dose may be administered as a single injection (5 mL) or divided into two separate injections (2.5 mL each); the injection should be administered slowly.