What is Degarelix (Firmagon®)?

Reviewed by: HU Medical Review Board | Last reviewed: July 2022 | Last updated: July 2022

Firmagon® (degarelix) is a Gonadotropin Releasing Hormone (GnRH) receptor antagonist. It is indicated for use in individuals with advanced prostate cancer. Degarelix is administered as a subcutaneous (under the skin) injection in your abdominal area. Individuals taking degarelix should also be monitored for cardiovascular complications, including a disorder of the heart’s electrical activity.

How does Firmagon® work?

Degarelix’s active ingredient is a Gonadotropin-Releasing Hormone (GnRH) receptor antagonist. This means, that its purpose is to block the GnRH receptor. Prostate cancer tumors are often fueled to grow by androgens, including testosterone. Turning off the body’s ability to produce testosterone, or reducing the amount made can potentially halt tumor growth. Degarelix blocks a key receptor in the pathway to making testosterone. When this receptor is deactivated, it decreases luteinizing hormone (LH) and follicle-stimulating hormone (FSH), which are key in making testosterone. When the making of these hormones is suppressed, testosterone production is decreased as well. This is also known as medical or chemical castration.

What are the possible side effects of Firmagon®?

Multiple clinical trials evaluated the safety and efficacy of degarelix. Possible side effects of degarelix include hot flashes, increased weight, decreased sex drive, erectile dysfunction, and increases in some liver enzymes. Injection site reactions are also possible while receiving degarelix, and are typically accompanied by swelling, redness, and pain. These are not all the possible side effects of degarelix. Talk to your doctor about what to expect or if you experience any changes that concern you during treatment with degarelix.

Things to note about Firmagon®

Several less common but more serious side effects can accompany degarelix including serious allergic reactions and disorder of the heart’s electrical activity. Individuals should be closely monitored for signs of these serious conditions. Signs of a serious allergic reaction that should be brought to your provider’s attention immediately include:

  • Severe itching
  • Trouble breathing or wheezing
  • Swelling of your face, lips, mouth, or tongue

Before starting degarelix talk to your provider if you:

  • Have any heart problems including long QT syndrome
  • Have problems with the levels of sodium, calcium, potassium, or magnesium in your blood
  • Have kidney or liver problems
  • Have any other medical conditions
  • Are currently taking any other medications (prescription and over-the-counter), vitamins, or herbal supplements

Taking Firmagon® to treat advanced prostate cancer

Degarelix is administered as a subcutaneous injection (under your skin). Your healthcare provider will administer the injection for you into your abdomen. Your provider will help you determine the best dosage and administration schedule for your situation. Patients should talk to their doctor if they have any questions, or if they have questions regarding their degarelix regimen.1

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