Andocur is an antiandrogenic hormone preparation. It inhibits the influence of androgens which are also produced - to a slight extent- in the female organism, and also exerts a progestational and antigonadotrophic effect.

Cyproterone acetate inhibits competitively the effect of androgens at androgen-dependent target organs, e.g. it shields the prostate from the effect of androgens originating from the gonads and/or the adrenal cortex.

Cyproterone acetate is a drug which is used in the treatment of prostate cancer. It is a type of hormonal therapy. Hormonal therapies interfere with the production or action of particular hormones in the body. Hormones are substances produced naturally in the body, where they act as chemical messengers and help control the activity of cells and organs.

How it works

In order to grow, most prostate cancers rely on supplies of the male hormone testosterone, which is produced by the testes and adrenal glands. On the surface of the prostate cancer cells are proteins called receptors. Cyproterone acetate has a structure similar to testosterone. It works by attaching itself to the receptors on the surface of the prostate cancer cells to block and prevent the attachment of testosterone.

The easiest way to understand the way cyproterone acetate works is to liken the process to that of a lock and key. The receptors are the lock and testosterone is the key. When testosterone comes into contact with the receptors it fits into the lock, activates the cancer cells to divide and the tumour grows. Cyproterone acetate imitates the action of testosterone and fits into the lock but the key does not turn and the cells do not divide. The cyproterone acetate remains in place and prevents the testosterone from reaching the cancer cells so they either grow more slowly or stop growing altogether.

Cyproterone acetate may be given together with injections of another type of hormonal therapy drug (goserelin, buserelin, triptorelin or leuprorelin). These drugs block the production of a hormone produced by the pituitary gland (luteinising hormone) which stimulates the production of testosterone.

Possible side effects

Each person's reaction to any medication is unique. Many people have very few side effects with cyproterone acetate, while others may experience more. The side effects described here will not affect everyone and may be different if you are having more than one drug.

We have outlined the most common side effects, so that you can be aware of them if they occur. However, we have not included those that are very rare and therefore extremely unlikely to affect you. If you do notice any effects which you think may be due to the drug, but which are not listed , please discuss these with your doctor or nurse.

You will see your doctor regularly while you have this treatment so that they can monitor the effects. This information should help you to discuss any queries about your treatment and its side effects with your doctor or nurse, as they are in the best position to help and advise you.

Some people may have some of the following side effects:

• Breast tenderness or fullness.
• Some men may notice slight breast swelling and tenderness. Your doctor can prescribe medication to reduce any discomfort.
• Tiredness and low mood.
• This is common during the first few weeks of treatment, but reduces with time.
• Breathlessness.
• You may have a feeling of mild breathlessness while having cyproterone acetate treatment. This will disappear if the treatment is stopped.
• Nausea (feelings of sickness),
• Vomiting and Diarrhoea. These are uncommon and if they occur they are usually mild and easily controlled. Nausea can sometimes be relieved by taking the tablet with food.

Let your doctor know if you have any of these side effects as medication can be prescribed to help.

• Lowering of libido (sex drive), and impotence (a loss of ability to have an erection). This is uncommon. If it occurs sexual function will return to normal after stopping the drug. Your doctor or nurse can discuss this with you. More information is available in the section on Sexuality and cancer.

Effect on liver function

Your doctor will take blood samples to measure how your liver is working, as cyproterone acetate can sometimes cause chemicals produced by the liver to become abnormal. If this happens the drug will be stopped and the liver function will return to normal.

Length of treatment

Your doctor will discuss the length of treatment that they feel is appropriate for your situation. It is often given for several months or years.

WARNING

Androcur is the most powerful of anti-androgen drugs and must not be taken by any patient with a medical condition, or one who is taking / has recently taken other drugs that are contra-indicated.

During treatment, liver function, adrenocortical function and the red blood-cell count should be checked regularly.

Direct hepatic toxicity, including jaundice, hepatitis and hepatic failure, which has been fatal in some cases, has been reported in patients treated with 200 - 300mg cyproterone acetate. Most reported cases are in men with prostatic cancer. Toxicity is dose-related and develops, usually, several months after treatment has begun. Liver function tests should be performed pre-treatment and whenever any symptoms or signs suggestive of hepatotoxicity occur. If hepatotoxicity is confirmed, cyproterone acetate should normally be withdrawn, unless the hepatotoxicity can be explained by another cause, e.g. metastatic disease, in which case cyproterone acetate should be continued only if the perceived benefit outweighs the risk.