Introduction

Fulvest 250 mg (Fulvestrant) Injection is a specialized anti-cancer medication manufactured by Eskayef Pharmaceuticals Ltd., one of Bangladesh’s leading pharmaceutical companies. Supplied by Orio Pharma, this estrogen receptor antagonist offers a targeted therapeutic approach for postmenopausal women with hormone receptor-positive breast cancer, addressing a critical need in advanced breast cancer treatment.

What is Fulvest?

Fulvest contains Fulvestrant, a pure estrogen receptor antagonist that functions by competitively binding to estrogen receptors with affinity comparable to estradiol. Unlike selective estrogen receptor modulators, Fulvestrant has no agonist effects and works by downregulating estrogen receptor protein in human breast cancer cells, effectively blocking estrogen’s growth-stimulating effects on hormone-dependent tumors.

Therapeutic Applications

Fulvest is indicated for multiple clinical scenarios in the treatment of hormone receptor (HR)-positive breast cancer:

1. Initial Endocrine Therapy: For HR-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in postmenopausal women not previously treated with endocrine therapy
2. Progressive Disease: For HR-positive advanced breast cancer in postmenopausal women with disease progression following endocrine therapy
3. Combination Therapy with CDK4/6 Inhibitors:
   • In combination with ribociclib as initial endocrine-based therapy or following disease progression for HR-positive, HER2-negative advanced or metastatic breast cancer
   • In combination with palbociclib or abemaciclib for HR-positive, HER2-negative advanced or metastatic breast cancer in women with disease progression after endocrine therapy

This versatility makes Fulvest an essential component in comprehensive breast cancer treatment strategies.

Mechanism of Action

Fulvestrant works through a sophisticated mechanism that specifically targets estrogen-dependent cancer growth:

Receptor Binding: Fulvestrant competitively binds to estrogen receptors with high affinity, displacing estradiol from binding sites.

Receptor Downregulation: Unlike other anti-estrogens, Fulvestrant significantly reduces cellular levels of estrogen receptors, leading to more complete estrogen signaling blockade.

Anti-Proliferative Effects: In laboratory studies, Fulvestrant demonstrated inhibition of growth in both tamoxifen-resistant and estrogen-sensitive breast cancer cell lines.

Pure Antagonist Activity: Fulvestrant shows no estrogen agonist effects in uterotrophic assays, confirming its pure antagonist nature without partial agonist properties that could potentially stimulate tumor growth.

Pharmacological Profile

In Vitro Studies: Fulvestrant acts as a reversible inhibitor of breast cancer cell growth, including tamoxifen-resistant cell lines.

In Vivo Tumor Studies: Fulvestrant delayed tumor establishment from human breast cancer xenografts in animal models and inhibited the growth of established tumors, including tamoxifen-resistant variants.

Endocrine Effects: In postmenopausal women, Fulvestrant treatment (250 mg monthly) causes no changes in plasma concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH), indicating absence of peripheral steroidal effects.

Dosage Guidelines

Standard Dosing Regimen:

• 500 mg administered intramuscularly into the buttocks (gluteal area)
• Administered as two 5 mL injections, one in each buttock
• Initial loading dose schedule: Days 1, 15, and 29
• Maintenance: Once monthly thereafter

Adjusted Dosing for Hepatic Impairment:

• 250 mg recommended for patients with moderate hepatic impairment
• Administered as one 5 mL injection following the same schedule

All injections should be administered slowly (1-2 minutes per injection) to minimize discomfort and ensure proper distribution of the medication.

Quality Assurance

Fulvest 250 mg Injection exemplifies Eskayef Pharmaceuticals’ commitment to manufacturing excellence in oncology products. Each batch undergoes rigorous quality control procedures to ensure sterility, potency, and consistency. As a supplier, Orio Pharma maintains strict adherence to international standards for storage, handling, and distribution of this critical medication.

Safety Profile

Most Common Adverse Reactions (occurring in ≥5% of patients receiving 500 mg dose):

• Injection site pain
• Musculoskeletal effects: Bone pain, arthralgia, back pain, pain in extremity, musculoskeletal pain
• Gastrointestinal effects: Nausea, vomiting, anorexia, constipation
• General symptoms: Headache, fatigue, asthenia, hot flashes
• Respiratory symptoms: Cough, dyspnea

Laboratory Abnormalities:

• Increased hepatic enzymes (ALT, AST, ALP) occurred in >15% of patients but were not dose-dependent

Important Precautions

Healthcare professionals should be aware of several important precautions when prescribing and administering Fulvest:

Bleeding Risk: Use with caution in patients with bleeding disorders, thrombocytopenia, or those taking anticoagulants.

Hepatic Impairment: Reduced dose (250 mg) recommended for patients with moderate hepatic impairment due to increased drug exposure.

Injection Technique: Exercise caution when administering at the dorsogluteal site due to proximity to the sciatic nerve.

Pregnancy Considerations: Can cause fetal harm; advise patients of reproductive potential about risks and need for contraception.

Laboratory Test Interference: May interfere with immunoassay measurements of serum estradiol, potentially resulting in falsely elevated levels.

Drug Interactions

Fulvestrant has a favorable drug interaction profile:

• No known clinically significant drug-drug interactions identified
• Although metabolized by CYP 3A4 in vitro, studies with ketoconazole (inhibitor) and rifampin (inducer) showed no significant alterations in Fulvestrant pharmacokinetics
• No dose adjustments needed for patients concurrently taking CYP 3A4 inhibitors or inducers

Storage Requirements

To maintain product stability and efficacy:

• Refrigerate between 2°-8°C
• Store in the original carton until time of use to protect from light
• Do not freeze

Global Availability

Orio Pharma ensures reliable worldwide delivery of Fulvest 250 mg within 3 to 7 working days. This commitment to rapid delivery acknowledges the time-sensitive nature of cancer treatment and the importance of maintaining consistent therapy protocols for patients with advanced breast cancer.

Expert Support

Orio Pharma‘s team of oncology specialists provides comprehensive information about Fulvest, including:

• Guidance on proper administration techniques
• Assistance with dosing protocols
• Support for management of potential side effects
• Information about combination therapy approaches

Manufacturer Information

Eskayef Pharmaceuticals Limited began its journey in 1990 when Transcom Group acquired the Bangladesh operation of SK&F, USA. With over three decades of experience, Eskayef has established itself as a premier pharmaceutical manufacturer, delivering world-class medicines domestically and internationally.