Fulvestrant (Faslodex) is an estrogen-receptor down-regulator. It binds to and inhibits the growth of estrogen-receptor-positive tumor cells. It is used in the treatment of patients with breast cancer.

Fulvestrant is a medication that is primarily used in the treatment of hormone receptor-positive (HR-positive) advanced breast cancer in postmenopausal women. It is classified as an estrogen receptor antagonist, which means it works by blocking the effects of estrogen in the body.

Fulvestrant (Faslodex) Uses:

• Breast cancer as monotherapy:
  • Used in the treatment of hormone-receptor (HR)-positive advanced breast cancer in postmenopausal women with disease progression following endocrine therapy.
  • Used in the treatment of HR-positive, human epidermal growth factor receptor 2 (HER2)-negative advanced breast cancer in postmenopausal women not previously treated with endocrine therapy
• Breast cancer as combination therapy:
  • Used in the treatment of HR-positive, HER2-negative advanced or metastatic breast cancer (in combination with ribociclib) in postmenopausal women as initial endocrine-based therapy or following disease progression on endocrine therapy
  • Used in the treatment of HR-positive, HER2-negative advanced or metastatic breast cancer (in combination with palbociclib or abemaciclib) in women with disease progression following endocrine therapy.

Fulvestrant (Faslodex) Dose in Adults

Note: If a woman is premenopausal or going through menopause, she should receive a luteinizing hormone-releasing hormone (LHRH) agonist along with fulvestrant if she is also taking abemaciclib, palbociclib, or ribociclib. In a study comparing different doses, the once-monthly maintenance dose of fulvestrant was given within a range of 28 days plus or minus 3 days.

Fulvestrant (Faslodex) Dose in the treatment of advanced Breast cancer in postmenopausal women who are HR-positive):

• Initial Dose: 500 mg administered via intramuscular injection on days 1, 15, and 29. These injections are given in the first month of treatment.
• Maintenance Dose: After the initial dose, a maintenance dose of 500 mg is given once a month. This is typically administered as a single intramuscular injection.

Fulvestrant (Faslodex) Dose in the treatment of advanced Breast cancer in postmenopausal women (HR-positive, HER2 negative):

• Initial Dose: 500 mg administered via intramuscular injection on days 1, 15, and 29. These injections are given in the first month of treatment.

• Maintenance Dose: After the initial dose, a maintenance dose of 500 mg is given once a month. This is typically administered as a single intramuscular injection.

Fulvestrant (Faslodex) Dose in the treatment of advanced or metastatic Breast cancer in postmenopausal women (HR positive, HER2 negative):

• Initial Dose: 500 mg of Fulvestrant is administered via intramuscular injection on days 1, 15, and 29. These injections are given in the first month of treatment.
• Maintenance Dose: After the initial dose, a maintenance dose of 500 mg of Fulvestrant is given once every 28 days. This is typically administered as a single intramuscular injection.
• It is important to administer Fulvestrant in combination with ribociclib and continue treatment until disease progression or unacceptable toxicity, as per the findings from the study conducted by Slamon et al. in 2018.

Note: For the specific dosing of ribociclib in combination with Fulvestrant, please refer to the Ribociclib monograph

Fulvestrant (Faslodex) Dose in the treatment of advanced or metastatic Breast cancer, (second-line endocrine-based combination therapy):

Adult females (HR-positive, HER2-negative):

• Initial Dose: 500 mg of Fulvestrant is administered via intramuscular injection on days 1, 15, and 29. These injections are given in the first month of treatment.
• Maintenance Dose: After the initial dose, a maintenance dose of 500 mg of Fulvestrant is given once every 28 days. This is typically administered as a single intramuscular injection.
• It is important to administer Fulvestrant in combination with either palbociclib or abemaciclib and continue treatment until disease progression or unacceptable toxicity, as per the findings from the studies conducted by Sledge et al. in 2017 and Turner et al. in 2018.

Fulvestrant (Faslodex) Dose in Children

Fulvestrant (Faslodex) Dose in the treatment of progressive precocious puberty in patients with McCune-Albright Syndrome (MAS): 

Female children aged 1 to 10 years:

• Initial Dose: 4 mg/kg of Fulvestrant administered via intramuscular injection once monthly.
• Maintenance Dose: The monthly injections are continued for 1 year or as directed by the healthcare professional.

The dosing regimen is based on the trial conducted in 30 girls aged ≤10 years (with an age range of 1 to 8.5 years), where Fulvestrant injections led to a significant decrease in vaginal bleeding and a reduction in rates of skeletal maturation.

Fulvestrant Pregnancy Category: D

• Studies on animals have shown that Fulvestrant may harm a developing fetus if given during pregnancy.
• Therefore, it's recommended that women who can become pregnant should have a pregnancy test within 7 days before starting Fulvestrant, and use effective contraception while receiving treatment and for 1 year after the last dose of Fulvestrant.
• It's also possible that Fulvestrant may affect a person's ability to have children, both in females and males, though it's not approved for use in men.

Use while breastfeeding

• The presence of Fulvestrant in breast milk is currently unknown.
• However, considering the potential for serious adverse effects on the breastfed infant, it is advised that lactating women should not breastfeed while receiving Fulvestrant treatment and for 1 year after the last dose of Fulvestrant.
• This precaution is taken to ensure the safety and well-being of the nursing infant.

Fulvestrant (Faslodex) Dose in Kidney Disease:

• The manufacturer's labeling does not provide any specific dosage adjustments for Fulvestrant as it has not been studied extensively in relation to renal elimination.
• However, it is important to note that Fulvestrant is eliminated from the body through means other than the kidneys, so no significant dosage adjustments are needed based on renal function.

Fulvestrant (Faslodex) Dose in Liver disease:

Note: The manufacturer's labeling has not provided dosage adjustments for severe liver impairment (Child-Pugh class C) due to limited studies on the use of Fulvestrant in such cases.

Common Side Effects of Fulvestrant (Faslodex):

• Central Nervous System:
  • Fatigue
  • Headache
• Endocrine & Metabolic:
  • Hot Flash
• Gastrointestinal:
  • Nausea
  • Diarrhea
  • Decreased Appetite
  • Abdominal Pain
  • Constipation
  • Vomiting
  • Stomatitis
• Hematologic & Oncologic:
  • Anemia
  • Lymphocytopenia
• Hepatic:
  • Increased Serum Aspartate Aminotransferase
  • Increased Serum Alanine Aminotransferase
  • Increased Liver Enzymes
• Infection:
  • Infection
• Local:
  • Pain At Injection Site
• Neuromuscular & Skeletal:
  • Arthralgia
• Renal:
  • Increased Serum Creatinine
• Respiratory:
  • Cough

Less Common Side Effects Of Fulvestrant (Faslodex):

• Cardiovascular:
  • Peripheral Edema
• Central Nervous System:
  • Dizziness
• Dermatologic:
  • Pruritus
  • Skin Rash
  • Alopecia
• Endocrine & Metabolic:
  • Weight Loss
• Gastrointestinal:
  • Anorexia
  • Dysgeusia
• Hematologic & Oncologic:
  • Leukopenia
  • Neutropenia
  • Thrombocytopenia
• Neuromuscular & Skeletal:
  • Ostealgia
  • Back Painn
  • Asthenia
  • Myalgia
  • Limb Pain
  • Musculoskeletal Pai
• Respiratory:
  • Dyspnea
• Miscellaneous:
  • Fever

Contraindications to Fulvestrant (Faslodex):

Fulvestrant is contraindicated in individuals with a known hypersensitivity or allergy to Fulvestrant or any component of the medication's formulation.

In addition to the contraindications mentioned above, according to Canadian labeling (which may differ from US labeling), Fulvestrant is also contraindicated in pregnant or lactating women.

Warnings and Precautions

Hypersensitivity

• Hypersensitivity reactions, which include skin rash and swelling of the face, have been reported with the use of Fulvestrant.

Injection-site reactions

• Fulvestrant injections may cause reactions at the injection site such as pain, tingling, or nerve-related symptoms like sciatica or neuropathy.
• Care should be taken when injecting at the dorsogluteal site (upper outer buttock) due to the close proximity of the underlying sciatic nerve.

Bleeding disorders

• Caution should be exercised when using Fulvestrant in patients with a history of bleeding disorders, including thrombocytopenia (low platelet count), or those receiving anticoagulant therapy (medication to prevent blood clotting).
• There is a risk of bleeding or hematoma (collection of blood) at the site of intramuscular (IM) injection.

Hepatic impairment

• In patients with moderate hepatic impairment, the exposure to Fulvestrant is increased, and therefore, a dosage adjustment is recommended.
• However, the safety and efficacy of Fulvestrant have not been established in patients with severe hepatic impairment.

Monitoring parameters:

• Liver function tests should be monitored regularly during Fulvestrant treatment.
• For females of reproductive potential, pregnancy testing is recommended within 7 days before starting Fulvestrant.
• Signs and symptoms of bleeding should be monitored closely during treatment with Fulvestrant.

How to administer Fulvestrant (Faslodex)?

Administration of Fulvestrant via Intramuscular Injection (IM)

Dosage:

• Administer a 500 mg dose as two 5 mL IM injections (one in each buttocks) slowly over 1 to 2 minutes per injection.

Caution:

• Use caution during injection if administering at the dorsogluteal site due to the proximity of underlying sciatic nerve.
• Refer to facility policy for IM administration of large volumes.

Preparation:

• Hold syringe upright and carefully tilt the syringe cap back and forth (without twisting) until the cap disconnects for removal.
• Pull cap off by pulling up without touching the syringe tip (to maintain sterility).
• Attach safety needle to syringe tip and twist firmly to lock.
• Remove needle cap by pulling straight off to avoid damaging the needle point.
• Remove needle sheath and expel excess air from the syringe prior to administration.

Mechanism of action of Fulvestrant (Faslodex):

• Fulvestrant is a medication that works as an estrogen receptor antagonist.
• It competes with estrogen molecules for binding to estrogen receptors on tumors and other tissues.
• When Fulvestrant binds to these receptors, it forms a complex inside the cell's nucleus.
• This complex leads to a decrease in the number of estrogen receptors and inhibits the growth of tumors.
• The effect of Fulvestrant is directly related to its dosage, meaning that higher doses can result in a stronger down-regulation of estrogen receptors and greater inhibition of tumor growth.

International Brand Names of Fulvestran:

• Faslodex
• Nilgaban
• Olvestran
• TEVA-Fulvestrant
• Fulvetraz
• Fulvenat

Fulvestran Brand Names in Pakistan:

There is no brand available in Pakistan