Abiraterone (Zytiga)

Abiraterone is a new type of hormone therapy. It is used to treat advanced prostate cancer in men who have already had other types of hormone therapy and chemotherapy containing docetaxel (Taxotere) that is no longer working. Clinical trials are also using abiraterone for earlier stages of prostate cancer and advanced breast cancer.

It is called abiraterone acetate, CB7630 or Zytiga.

Abiraterone works in a different way to other hormone treatments for prostate cancer. The male hormone testosterone stimulates prostate cancers to grow. Stopping the body making testosterone can slow the growth of the cancer, or even shrink it. Most testosterone is made by the testes. But a small amount of testosterone is made by other tissues in the body including the cancer itself. To make testosterone the body needs an enzyme called cytochrome P17 (CYP17). Abiraterone acetate blocks cytochrome P17, which stops the testes and other tissues in the body making testosterone.

You have abiraterone as tablets. The usual dose is 4 tablets taken together once a day. You should swallow them whole with a glass of water on an empty stomach. The tablets should be taken at least one hour before food, or at least 2 hours afterwards. You take abiraterone with a steroid called prednisolone to help reduce some of the side effects.

It is very important that you take the tablets according to the instructions your doctor or pharmacist gave you. For example, whether you have a full or empty stomach can affect how much of the drug gets into your bloodstream. You should take the right dose, not more or less. And never stop taking a cancer drug without talking to your specialist first. There is important information about taking medicines in this section.

The side effects associated with abiraterone are listed below. Because abiraterone is a relatively new drug we are still learning about the side effects, especially longer term ones. If you have a new symptom or side effect always tell your doctor or specialist nurse so that they can work out if it is due to the drug or something else. They can then work out what you need.

You can use the links below to find out more about each side effect. For general information, see our cancer drug side effects section.

More than 10 in every 100 people have one or more of these.

• Tiredness (fatigue)
• Swelling of the legs due to fluid build up (known as peripheral oedema) affects about 3 in 10 men (30%)
• Low levels of potassium in the blood (hypokalaemia) occur in 17 out of 100 men (17%) and you will have blood tests to check your potassium levels – if you have muscle twitching or a fast heart beat contact your doctor immediately
• Aching joints and muscles occur in about 1 in 4 men (25%)
• High blood pressure during treatment happens in about 1 in 10 men (10%) – your nurse or GP will check your blood pressure regularly
• Bladder infections affect just over 1 in 10 men (10%) – let your doctor or nurse know if you are passing urine more often or have pain when passing it

Between 1 and 10 in every 100 people have one or more of these.

• A mild effect on the liver that is unlikely to cause symptoms and will almost certainly go back to normal when you finish treatment – you will have regular blood tests to check how well your liver is working
• Heart problems, including a faster heart beat, a change to the heart rhythm and chest pain
• This drug may have a harmful effect on a developing baby so do talk to your doctor or nurse about contraception before having treatment if there is any chance that your partner could become pregnant
• Bone thinning (osteoporosis) can occur with advanced prostate cancer and abiraterone can increase this – it can make bones more likely to break

You won’t get all these side effects. A side effect may get worse through your course of treatment. Or you may have more side effects as the course goes on. This depends on

• How many times you've had a drug before
• Your general health
• How much of the drug you have (the dose)
• Other drugs you are having

Talk to your doctor, pharmacist or nurse about all your side effects so they can help you manage them.

Tell your doctor about any other medicines you are taking, including vitamins, herbal supplements and other over the counter remedies – some drugs can react together.