Fulvestrant

Reviewed on 3/8/2022

Generic Name: Fulvestrant

Brand Name: Faslodex

Drug Class: Antineoplastics, Estrogen Receptor Antagonist

What Is Fulvestrant and How Does It Work?

Fulvestrant is a prescription medication used for the treatment of advanced breast cancer.

  • Fulvestrant is available under the following different brand names: Faslodex

What Are Dosages of Fulvestrant?

Adult dosage

Injectable solution

  • 250mg/5mL

Pediatric dosage

Injectable solution

  • 50mg/mL

Advanced Breast Cancer

Adult dosage

Monotherapy

  • 500 mg IM on days 1, 15, 29, then once monthly thereafter

Combination therapy with palbociclib or abemaciclib

  • Fulvestrant 500 mg IM on days 1, 15, 29, and once monthly thereafter AND
  • Palbociclib 125 mg orally every day for days 1-21 of each 28-day cycle OR
  • Abemaciclib 150 mg orally twice every day

Combination with ribociclib

  • Fulvestrant 500 mg IM on days 1, 15, 29, and once monthly thereafter AND
  • Ribociclib 600 mg for days 1-21 of each 28-day cycle

Dosage Considerations – Should be Given as Follows: 

  • See “Dosages”

What Are Side Effects Associated with Using Fulvestrant?

Common side effects of Fulvestrant include:

  • injection site pain
  • nausea
  • muscle, joint, and bone pain
  • headache
  • back pain
  • tiredness
  • pain in arms, hands, legs, or feet
  • hot flashes
  • vomiting
  • loss of appetite
  • weakness
  • cough
  • shortness of breath
  • constipation
  • increased liver enzymes
  • diarrhea

Serious side effects of Fulvestrant include:

  • injection site nerve damage leading to numbness, tingling, and weakness.

Rare side effects of Fulvestrant include:

  • none 
This is not a complete list of side effects and other serious side effects or health problems that may occur as a result of the use of this drug. Call your doctor for medical advice about serious side effects or adverse reactions. You may report side effects or health problems to FDA at 1-800-FDA-1088.

QUESTION

A lump in the breast is almost always cancer. See Answer

What Other Drugs Interact with Fulvestrant?

If your medical doctor is using this medicine to treat your pain, your doctor or pharmacist may already be aware of any possible drug interactions and may be monitoring you for them. Do not start, stop, or change the dosage of any medicine before checking with your doctor, health care provider, or pharmacist first.

  • Fulvestrant has severe interactions with no other drugs.
  • Fulvestrant has serious interactions with no other drugs.
  • Fulvestrant has moderate interactions with the following drug:
    • siponimod
  • Fulvestrant has minor interactions with the following drugs:

This information does not contain all possible interactions or adverse effects. Visit the RxList Drug Interaction Checker for any drug interactions. Therefore, before using this product, tell your doctor or pharmacist of all the products you use. Keep a list of all your medications with you and share this information with your doctor and pharmacist. Check with your health care professional or doctor for additional medical advice, or if you have health questions, concerns.

What Are Warnings and Precautions for Fulvestrant?

Contraindications

  • Hypersensitivity to fulvestrant or any component of the formulation

Effects of drug abuse

  • None

Short-Term Effects

  • See “What Are Side Effects Associated with Using Fulvestrant?”

Long-Term Effects

  • See “What Are Side Effects Associated with Using Fulvestrant?”

Cautions

  • Caution in bleeding diathesis, thrombocytopenia, therapeutic anticoagulation
  • Systemic exposure was increased in patients with moderate hepatic impairment (see Dosage Modifications)
  • Advise females of reproductive potential of the potential risk to a fetus and to use effective contraception; see Pregnancy section
  • Therapy can interfere with estradiol measurement by immunoassay, resulting in falsely elevated estradiol levels
  • Injection site-related events including sciatica, neuralgia, neuropathic pain, and peripheral neuropathy reported; caution should be taken while administering therapy at dorsogluteal injection site due to proximity of the underlying sciatic nerve

Pregnancy and Lactation

  • Based on findings from animal studies and its mechanism of action, fulvestrant can cause fetal harm when administered to a pregnant woman
  • In animal reproduction studies, administration of fulvestrant to pregnant rats and rabbits during organogenesis resulted in embryo-fetal toxicity at daily doses that are significantly less than the maximum recommended human dose
  • Advise pregnant women of the potential risk to a fetus
  • Advise females of reproductive potential to use effective contraception during treatment and for 1 year after the last dose
  • Pregnancy testing is recommended for females of reproductive potential within 7 days before initiating fulvestrant.
  • Lactation
    • Excretion in human milk unknown
    • Detected in rat milk
    • Because of the potential for serious adverse reactions in breastfed infants, advise lactating women not to breastfeed during treatment and for 1 year after the final dose
References
Medscape. Fulvestrant.

https://reference.medscape.com/drug/faslodex-fulvestrant-342224#6

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