Faslodex is a brand name for the medication fulvestrant. It belongs to a group of drugs called estrogen receptor antagonists or selective estrogen receptor degraders (SERDs). It's primarily used in breast cancer treatment.

Purpose

Faslodex is used to treat hormone receptor-positive breast cancer in postmenopausal women, particularly when the cancer is:

  • Advanced or metastatic (spread to other parts of the body)
  • Progressing after treatment with other anti-estrogen medications
  • HR-positive, HER2-negative (specific types of breast cancer)

It may be used alone or in combination with other medications like CDK4/6 inhibitors (such as palbociclib).

How It Works

Many breast cancers need estrogen (a female hormone) to grow. These are called "estrogen receptor-positive" or "hormone receptor-positive" breast cancers. Faslodex works in two important ways:

  1. It blocks estrogen receptors on cancer cells, preventing estrogen from attaching to them
  2. It actually reduces the number of estrogen receptors in cancer cells

Without estrogen stimulation, these cancer cells grow more slowly or stop growing altogether.

Administration

  • Faslodex is administered as an injection into the muscle (intramuscular injection), typically in the buttocks
  • It's given by healthcare professionals in a clinic or hospital setting
  • The standard dose is usually given once a month, with an additional dose two weeks after the first injection when starting treatment
  • Each dose is typically divided into two injections (one in each buttock)

Common Side Effects

Many patients experience some side effects, which are usually manageable:

  • Injection site pain, redness or swelling
  • Hot flashes or night sweats
  • Nausea
  • Fatigue or weakness
  • Bone, joint, or muscle pain
  • Headache
  • Back pain
  • Constipation
  • Loss of appetite

Serious Side Effects to Watch For

Contact your healthcare provider immediately if you experience:

  • Signs of liver problems: yellowing of skin/eyes, dark urine, pain in your upper abdomen
  • Allergic reactions: rash, itching, swelling of the face or throat, severe dizziness
  • Unusual bleeding or bruising
  • Severe or persistent headaches
  • Extreme fatigue
  • Persistent pain at the injection site, especially with swelling or hardness

Important Precautions

  • Liver function: Your doctor will monitor your liver function through blood tests
  • Bone health: Faslodex may contribute to bone loss over time, so your doctor might recommend bone density testing
  • Blood disorders: Regular blood tests may be needed to check for potential blood-related side effects
  • Pregnancy and breastfeeding: Although Faslodex is typically used in postmenopausal women, it can harm developing fetuses and should not be used during pregnancy
  • Other medical conditions: Inform your doctor about all medical conditions, especially bleeding disorders or liver problems

Drug Interactions

Tell your healthcare team about all medications you take, including:

  • Prescription medications
  • Over-the-counter drugs
  • Supplements and herbal remedies

Particular care is needed with blood thinners, as interactions may occur.

Follow-up Care

While on Faslodex, you'll need:

  • Regular check-ups to monitor your response to treatment
  • Routine blood tests
  • Imaging studies to assess how the cancer is responding
  • Open communication with your healthcare team about side effects