Health Centres - Cyprostat
How does it work?
Cyprostat tablets contain the active ingredient cyproterone acetate, which is a type of medicine known as an anti-androgen. (NB. Cyproterone acetate is also available without a brand name, ie as the generic medicine.)
Androgens are male hormones such as testosterone. They have many actions in the body and work by binding to receptors on cells and influencing the actions of these cells. Prostate cancers generally require the androgen testosterone in order to grow and spread.
Cyproterone acetate is used in the treatment of prostate cancer. It works by preventing testosterone from binding to androgen receptors in the prostate gland. It also acts on an area of the brain called the hypothalamus, which ultimately results in a reduction in the amount of testosterone produced by the body. It therefore starves prostate cancer cells of testosterone, which prevents them growing. Eventually the prostate tumour will shrink.
In the treatment of prostate cancer, cyproterone acetate is usually used in combination with another type of medicine known as a gonadorelin or LHRH analogue. LHRH analogues are one of the standard treatments for prostate cancer and include medicines such as buserelin, goserelin, leuprorelin and triptorelin. This class of medicines also work by decreasing testosterone levels and starving the cancer of testosterone. However, at the start of treatment they can cause a short-term increase in testosterone levels that makes the symptoms worse (flare) before they start to improve. Cyproterone acetate is used to block the effects of this increased testosterone and prevent the symptom flare during initial treatment with this type of medicine.
Cyproterone is also used on its own to treat prostate cancer in men for whom LHRH analogues or surgery are not suitable. In this case, cyproterone is taken long-term to reduce the symptoms of the cancer.
Lastly, cyproterone is used to control hot flushes that may arise in men who are having treatment with LHRH analogues, or who have had their testicles removed (orchidectomy) as part of their treatment.
What is it used for?
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Prostate cancer (see details above).
Warning!
- This medicine can make you feel tired or weak and so may reduce your ability to drive or operate machinery safely. Do not drive or operate machinery until you know how this medicine affects you and you are sure it won't affect your performance.
- This medicine may sometimes cause liver problems. For this reason, your doctor will want to monitor your liver function before you start treatment and regularly during treatment. This will usually require a blood test. You should let your doctor know if you experience any symptoms that could indicate a problem with your liver during treatment, so that your liver function can be checked.

