Degarelix is a type of hormone therapy called a gonadotrophin-releasing hormone (GnRH) antagonist or blocker. Its brand name is Firmagon. You may be able to take degarelix if you have prostate cancer that has spread (metastasised) to other parts of the body (advanced or metastatic prostate cancer).¹

Degarelix works by blocking the message from your brain that tells your testicles to make the hormone testosterone.² Without testosterone, the prostate cancer cells stop growing or grow more slowly, wherever they are in the body. Advanced prostate cancer is not curable but degarelix may keep it under control for many months or years before you and your specialist team may need to consider other treatments.

Degarelix starts to lower your testosterone levels within the first day of taking it.³ This is different to LHRH agonists (another type of hormone therapy), which cause a temporary rise in testosterone levels after the first injection. The rise in testosterone could cause your cancer to grow more quickly for a short time, which is known as a flare. If you are taking an LHRH agonist, you may have a short course of another type of drug, called an anti-androgen, to help stop flare happening.⁴ Because degarelix does not cause a temporary rise in testosterone levels, you will not need to take an anti-androgen.³

Degarelix is not available in every hospital. It is newer than most other hormone therapies currently available so we do not have as much information about how effective it is in the long term or about possible long-term side effects.

You will have degarelix as an injection just under the skin of your stomach area (abdomen). The first time you have degarelix, you will have two injections on the same day.¹ One injection will usually be given on the left side of your stomach area and the other on the right side. The amount of drug in each of these injections (dose) will be 120mg.¹ After this, you will have one injection of a smaller amount of degarelix (80mg) once a month.¹ Your GP, practice nurse or district nurse may give you your injection, or you may have it at your local hospital. Tell your doctor or nurse about any herbal or complementary medicines you are taking or are thinking about taking because they can interfere with your degarelix treatment.

You may find that the first two injections cause your skin to darken, redden, harden or swell. You may also find that you have some discomfort or pain in the area around where you have the injections. These problems are less likely to happen when you are having the monthly injections.¹

You can read about how your treatment will be monitored on our Hormone therapy page.

What happens if I miss an injection?
If your injection is a few days late, this should not cause your prostate cancer to spread. If you miss your treatment for longer than this, your body may start producing more testosterone and this could cause the cancer cells to grow. If you think you have missed an injection, tell your doctor or nurse.

Like all hormone therapy drugs, degarelix can cause side effects. Some men get very few side effects or none at all, and others get more. There is no way of knowing in advance which side effects you will get and how bad they will be.

Many side effects will only last for as long as you are taking degarelix. However, if you are taking degarelix for a long period of time, it may take several months after finishing treatment for side effects to stop.

We have described the most common side effects here.¹ If you have any concerns about your side effects, or if you notice any other new symptoms while you are having treatment, speak to your doctor or nurse. You can also call our confidential Helpline.

You can read more about the side effects of hormone therapy and ways to manage or reduce them on our Living with hormone therapy page.

Hot flushes

Hot flushes are one of the most common side effects of degarelix.¹ They give you a sudden feeling of warmth in the upper body and can be similar to the ones that women get when they go through the menopause. Some men may also find that they sweat more than they used to, particularly at night. Hot flushes can vary from a few seconds of feeling overheated to a few hours of sweating that can stop you from sleeping or make you feel uncomfortable.

Weight gain

You may put on weight, particularly around the waist.

A drop in the number of red blood cells (anaemia)

Men taking degarelix often develop a condition called anaemia, which is a drop in the number of red blood cells. Usually this is mild and does not cause any problems, but it may make you feel a little breathless and tired. Tell your doctor or nurse if you are feeling like this.

Tiredness

You may feel tired and have trouble sleeping while you are taking degarelix. Tiredness can affect your ability to drive and use machines.

Bone thinning

Degarelix lowers the levels of testosterone in your body. Having lower levels of testosterone for a long time may cause your bones to become weaker. If bone thinning is severe, it can lead to a condition called osteoporosis. This can increase your risk of bone fractures. If you already have osteoporosis, have a family history of osteoporosis or have had fractures in the past, talk to your doctor before you start treatment with degarelix.

Breast swelling or tenderness

Some men may experience swelling (gynaecomastia) and tenderness in the breast area. This can affect one or both sides and can range from mild sensitivity to ongoing pain. The amount of swelling can also vary from a small amount to a more noticeable enlargement.

Loss of sex drive and erection problems

Degarelix lowers your levels of testosterone. As testosterone is the hormone responsible for giving you your sex drive, men taking degarelix may lose their desire for sex (libido). Some men may also have problems getting and keeping an erection (erectile dysfunction). In most cases, this lasts for as long as you are on degarelix and may take a while to return to normal if you stop treatment. Some men may also find that degarelix makes their testicles smaller.

Diabetes

Degarelix can sometimes make diabetes more difficult to control. If you have diabetes, you may have to measure your blood sugar levels more often.

Other side effects

Other side effects that you may get include:

• chills, fever, or a feeling like you have the flu straight after your injection
• feeling dizzy or sick
• loose or watery stools (diarrhoea)
• headaches, or pain in your back, joints or bones
• a rash on your skin.

Degarelix may also increase your risk of getting heart rhythm problems. Before you start taking degarelix, tell your doctor if you already have heart problems or if you are taking medicines to treat a heart problem. You should also speak to your doctor if you notice anything different about how your heart is beating once you have started treatment, for example, if your heart is beating faster or slower than normal.

Reporting unusual side effects: The Yellow Card Scheme

If you think you are experiencing a side effect from your medication that is not mentioned in the information leaflet that comes with it, then you can report it using the Yellow Card Scheme. This is run by the Medicines and Healthcare products Regulatory Agency (MHRA). The MHRA will investigate and if they find a problem with a medication then they will take action to protect the public. There are three ways you can report a side effect:

• Use the online Yellow Card form
• Ask your pharmacist for a Yellow Card form
• Call the Yellow Card freephone on 0808 100 3352

You can take degarelix for as long as it is controlling your cancer. Read our information about treating prostate cancer after hormone therapy for information on other treatments that can be used if degarelix is no longer controlling your cancer. You can also speak to your doctor or nurse, or call our confidential Helpline.

Reviewed by:

• Simon Brewster, Consultant Urological Surgeon, Churchill Hospital, Oxford, and Honorary Senior Lecturer, University of Oxford
• Patricia McClurey, Specialist Nurse Prostate Cancer, James Cook University Hospital, Middlesbrough
• Debbie Victor, Uro-Oncology CNS, Royal Cornwall Hospital
• Cathryn Woodward, Consultant Clinical Oncologist, Addenbrooke's Hospital, Cambridge
• The Prostate Cancer Charity Support and Information Specialist Nurses
• Prostate Cancer Voices

Written and edited by:
The Prostate Cancer Information Team

Sources of information used in the production of this fact sheet:

1. Summary of Product Characteristics: Firmagon 80/120mg. Bayer HealthCare September 2009. Available at: http://emc.medicines.org.uk

2. Steinberg M. Degarelix: a gonadotropin-releasing hormone antagonist for the management of prostate cancer. Clin Ther. 2009;31 Pt 2:2312-31.

3. Klotz, Laurence. Boccon-Gibod, Laurent. Shore, Neal D. Andreou, Cal. Persson, Bo-Eric. Cantor, Per. Jensen, Jens-Kristian. Olesen, Tine Kold. Schroder, Fritz H. The efficacy and safety of degarelix: a 12-month, comparative, randomized, open-bale, parallel-group phase III study in patients with prostate cancer. BJU International. 2008 102, 1531-1538.

4. National Institute for Health and Clinical Excellence. 2008. Prostate cancer: diagnosis and treatment. Available at http://www.nice.org.uk/guidance/index.jsp?action=byID&o=11924