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What is Faslodex® ? (fulvestrant)

Faslodex is an estrogen receptor antagonist used to treat certain cases of hormone receptor positive (HR+) advanced or metastatic breast cancer. It is approved to treat: 1,2

  • HR+, human epidermal growth factor receptor 2 negative (HER2-) advanced breast cancer in women who are postmenopausal and have not been previously treated with endocrine therapy
  • HR+ advanced breast cancer in women who are postmenopausal and whose disease has progressed after treatment with other endocrine therapy
  • HR+, HER2- advanced breast cancer or breast cancer that has metastasized (spread to other parts of the body) in combination with Verzenio™ (abemaciclib) or Ibrance® (palbociclib) in women whose disease has progressed after treatment with other endocrine therapy

Faslodex is manufactured by AstraZeneca.

What is the ingredient in Faslodex?

The active ingredient in Faslodex is fulvestrant, an estrogen receptor antagonist.1

How does Faslodex work?

Many breast cancers have estrogen receptors on the surface of their cells. Estrogen can connect to these receptors and stimulate the growth of these breast cancers. Faslodex binds to the estrogen receptor and can help block or slow the breast cancer’s growth.1

What are some of the possible side effects of Faslodex?

The most common side effects experienced by patients receiving Faslodex in clinical trials included:1,2

  • Injection site pain
  • Nausea
  • Joint, muscle, or bone pain
  • Headache
  • Back pain
  • Fatigue or weakness
  • Pain in the arms or legs
  • Hot flashes
  • Vomiting
  • Loss of appetite
  • Cough
  • Shortness of breath
  • Constipation
  • Diarrhea
  • Increases in liver enzymes

In some people, Faslodex may cause a hypersensitivity reaction (severe allergic reaction), potentially causing itching, hives, difficulty breathing, or swelling of the face, lips, tongue, or throat.2

Faslodex may cause nerve damage where it in injected (in the buttocks), which may cause numbness, tingling, and/or weakness in the legs. These symptoms should be reported to a healthcare professional.2

Things to know about Faslodex

Before starting treatment with Faslodex, patients should discuss with their doctor all their health conditions, especially:2

  • Any liver problems
  • Problems with bleeding and/or low platelet levels in the blood
  • If patients are pregnant, or planning to become pregnant
  • If patients are breastfeeding, or planning to breastfeed

Faslodex may cause harm to an unborn baby and should not be used by women who are pregnant. Women who can become pregnant should use effective contraception during Faslodex treatment and for at least one year after their final dose.2

It is not known if Faslodex can pass into breastmilk. Women should not breastfeed during treatment with Faslodex and for at least one year after their final dose of fulvestrant.2

Before starting treatment with Faslodex, patients should talk to their doctor about all their medications (prescription and over-the-counter), herbal supplements, and vitamins they are taking. Some of these may affect the way Faslodex works, or Faslodex may affect how other medicines work.2

Dosing information

Faslodex is given as an intramuscular (into the muscle) injection into the buttocks. The recommended dose is 500 mg given slowly (1-2 minutes per injection) as two injections, one in each buttock, on days 1, 15, and 29 of treatment and then once monthly.1

In women with liver impairment, the dose may be reduced to 250 mg as one injection given in the buttock on days 1, 15, and 29 of treatment and then once monthly.1

For more information, read the full prescribing information of Faslodex.

Patients should talk to their doctor if they have any questions, or if they have questions regarding their Faslodex regimen.

  1. Faslodex prescribing information. AstraZeneca. Available at https://www.azpicentral.com/faslodex/faslodex.pdf. Accessed 9/20/18.
  2. Faslodex product website. AstraZeneca. Available at https://www.faslodex.com/. Accessed 9/20/18.