Cyproterone acetate (Cyprostat ®)
Cyproterone acetate is a hormonal treatment used to treat prostate cancer. It’s also called Cyprostat ®.
This information is best read with our general information on prostate cancer and advanced prostate cancer.
You will see a doctor or nurse regularly while you have this treatment so they can monitor its effects.
How cyproterone acetate works
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Hormones are substances produced naturally in the body. They act as chemical messengers and help control the activity of cells and organs. Hormonal therapies interfere with the way hormones are made or how they work in the body.
Most prostate cancers need the hormone testosterone to grow. Almost all testosterone in men is made by the testicles. A very small amount is made by the adrenal glands, which sit above the kidneys.
Cyproterone acetate reduces the amount of testosterone made by your body. This reduces testosterone levels and may shrink the prostate cancer or stop it growing.
When cyproterone acetate is given
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You can have cyproterone acetate on its own if other treatments, such as surgery, are not suitable.
You can also have cyproterone acetate for the first few weeks when you start taking other hormonal treatments, such as goserelin, buserelin, triptorelin or leuprorelin. These drugs cause a short-term rise in testosterone. This makes symptoms such as bone pain or problems passing urine worse before they get better. Doctors call this tumour flare. Cyproterone helps prevent this happening.
You can have cyproterone acetate for four weeks to reduce hot flushes that are caused by hormonal treatments, or if you have had your testicles removed (orchidectomy).
Your doctor or nurse will explain why you are having cyproterone acetate and how long you will take it for.
Taking your cyproterone acetate tablets
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You take cyproterone acetate as tablets one to three times a day. Take the tablets after meals and swallow them whole with a glass of water. Always take your tablets exactly as your nurse or pharmacist explained. This is important to make sure they work as well as possible for you.
It’s important that you do not stop taking any of your tablets unless advised by your doctor. Here are some important things to remember:
Don’t take a double dose if you forget to take your tablet. Just take your next dose at the usual time.
Keep tablets in the original package and at room temperature, away from heat and direct sunlight.
Keep them safe and out of the reach of children.
Get a new prescription before you run out of tablets, and make sure you have plenty for holidays.
Return any remaining tablets to the pharmacist if your treatment is stopped.
Possible side effects ofcyproterone acetate
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We explain the most common side effects of cyproterone acetate here. But we don’t include all the rare ones that are unlikely to affect you. You may get some of the side effects we mention, but you are very unlikely to get all of them. If you are having other drugs as well, you may have some side effects that we don’t list here.
Always tell your doctor or nurse about the side effects you have. They can prescribe drugs to help control side effects and give you advice about managing them.
Most men have some loss of sex drive (libido) and erection difficulties (impotence) during hormonal therapy. These often return to normal after stopping the drug. Your doctor can prescribe treatments to help with erection difficulties. These treatments don’t increase sex drive. If you need support coping with sexual difficulties, your nurse or doctor can give you information and refer you for specialist support services.
You may notice you have gained weight, or your ankles and legs may be swollen. This is due to fluid building up. Tell your doctor or nurse if this happens. The swelling will get better after your treatment ends.
You may experience mood swings or feel anxious, restless or depressed. This is more likely if you already have depression or low moods. Your doctor or nurse can give you support or advice about this.
Hot flushes and sweats
These are common and can be mild or more severe. During a hot flush, you feel warmth in your neck and face and your skin may redden. Mild flushes can last for a few seconds or up to a couple of minutes. More severe flushes can last for 10 minutes or more. You may sweat, then feel cold and clammy. Some people feel anxious or irritable during a hot flush.
There are things you can do to try to reduce flushes, such as cutting down on nicotine, alcohol, and hot drinks that contain caffeine such as tea and coffee. Hot flushes and sweats may lessen as your body adjusts to hormonal treatment. They usually stop completely a few months after treatment finishes.
Breast swelling or tenderness
You may notice slight breast swelling and tenderness. This is called gynaecomastia. Your doctor can advise you about how this can be prevented or treated.
You may feel tired with little energy while taking cyproterone acetate. Try to pace yourself if you feel tired. Aim for a balance between having rest periods and being physically active. There is evidence that doing exercise can reduce tiredness in men taking hormonal therapy. Ask your doctor or nurse what is safe for you to do. If tiredness makes you feel sleepy, don’t drive or use machinery.
You may feel slightly short of breath while you are taking cyproterone acetate. Talk to your doctor or nurse if this happens. This should stop when the treatment finishes.
Your doctor will take blood samples to test how well your liver is working. Cyproterone acetate can sometimes cause changes in the way your liver works. If this happens, the drug will be stopped and your liver should return to normal. Tell your doctor if you notice any yellowing of your skin or eyes.
Blood clot (thrombosis)
Cyproterone acetate may increase your risk of getting a blood clot if you have a history of clots, sickle cell anaemia or diabetes. If you are taking cyproterone acetate and you have any pain, redness or swelling in a leg, breathlessness or chest pain, let your doctor know immediately.
Always let your doctor or nurse know about any side effects you have. There are usually ways in which they can be controlled or improved.
Other information about cyproterone acetate
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Change in blood sugar levels
If you have diabetes, your blood sugar levels may be slightly higher than usual and you may need to check them more regularly. Your doctor will talk to you about how to manage this. Your blood sugar levels should return to normal after you finish treatment with cyproterone acetate.
Cyproterone acetate can interact with other drugs. This includes medicines you can buy in a shop or chemist. Tell your doctor about any medicines you are taking, including ones you can buy for yourself, complementary therapies, vitamins and herbal drugs.
Your doctor will advise you not to father a child during treatment. This is because the drugs may harm a developing baby. It’s important to use effective contraception during and for a few months after treatment. You can talk to your doctor or nurse about this.
If you need to go into hospital for any reason other than cancer, always tell the doctors and nurses that you are taking cyproterone acetate. Explain you are taking hormonal therapy that you should not stop or restart without advice from your cancer doctor. Tell them the name of your cancer doctor so they can ask for advice.
It’s a good idea to know who you should contact if you have any problems or troublesome side effects when you’re at home.
The information in this section has been produced in accordance with the following sources and guidelines:
British National Formulary. www.bnf.org/bnf/index.htm (accessed June 2014)
electronic Medicines Compendium (eMC). www.medicines.org.uk (accessed June 2014).
NICE clinical guideline 175. Prostate cancer: diagnosis and treatment. 2014.
If you’d like further information on the sources we use, please feel free to contact us
Thanks to Marilyna Chong, Pharmacist - Cancer Services, who reviewed this edition.
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