Fulvestrant (Faslodex ®)
Fulvestrant is a type of hormonal therapy drug used to treat breast cancer that has spread in women who have been through the menopause.
It’s best to read with our information on breast cancer or secondary breast cancer in women, We also have information about breast cancer in men which explains the hormonal therapies used in men.
Hormones are substances produced naturally in your 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.
Many breast cancers rely on the hormone oestrogen to grow. This type of breast cancer is called oestrogen-receptor positive (ER positive) breast cancer. These cancers have receptors (proteins) on the breast cancer cells which let hormones, such as oestrogen, attach to the cell.
Fulvestrant blocks the receptors and stops oestrogen reaching the cancer cells. This slows down or stops the cancer cells from growing. Fulvestrant also reduces the number of receptors on the breast cancer cells.
When fulvestrant is given
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Fulvestrant is usually given to women who have already been treated with other hormonal therapies but they are no longer controlling the cancer. Your doctor or nurse will explain how long you should take fulvestrant for. You usually have it for as long as it is working well for you.
You are given fulvestrant as two slow intramuscular injections, one into each buttock. It’s given once a month with an additional dose two weeks after the first dose only.. You can have it at the hospital or a practice nurse or district nurse can usually give it to you.
Having the injection can be a bit uncomfortable but it doesn’t take long. The area around the injection site may be red afterwards.
Possible side effects of fulvestrant
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We explain the most common side effects of fulvestrant 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 some side effects and give you advice about managing side effects.
Feeling or being sick, and losing your appetite
Let your doctor or nurse know if this happens. If it doesn’t get better your doctor can prescribe drugs to control it. If you don’t have much appetite try to eat lots of small meals or snacks regularly.
You may have some pain, redness and swelling at the injection site. You may need to take some simple pain killers and let your doctor know if it becomes a problem.
Tiredness and lack of energy
You may feel tired, sleepy or feel you have no energy when you start taking fulvestrant. Try to pace yourself until this improves. It’s important to get the right balance between having enough rest and being physically active. Even regular short walks will help you to feel less tired. If you feel sleepy, don’t drive or operate machinery.
Fulvestrant may cause changes in the way your liver works. You are very unlikely to notice any problems but your doctor will take regular blood samples to check your liver is working properly.
Hot flushes and sweats
These are often mild but this can vary. Hot flushes may lessen after the first few months. Cutting down on nicotine, and alcohol and on hot drinks containing caffeine, such as tea and coffee, can help. Dress in layers, so you can remove clothes as needed. Natural fabrics, such as cotton, can feel more comfortable.
If hot flushes are troublesome tell your doctor. Low doses of certain antidepressant drugs can help to reduce flushes.
This is usually mild. If it doesn’t get better your doctor can prescribe drugs to control diarrhoea. Make sure you drink at least two litres (three and a half pints) of fluids every day if you have diarrhoea.
If you have headaches let your doctor or nurse know. They can usually be controlled with non-prescription pain killers.
Back/ joint or muscle pain
You may have back pain or pain in your joints or muscles. Let your doctor and nurse know if this happens. They can prescribe painkillers and give you advice. Tell them if it doesn’t get better.
You may get a mild rash. Tell your doctor or nurse if this happens. It’s very important to contact your doctor straight away if you get a severe skin rash.
Less common side effects
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Let your doctor know if you have pain or discomfort when you pass urine, if you need to go more often or if your urine is cloudy or smelly. Drink lots of fluids if you think you may have a urine infection.
Blood clots (thrombosis)
Fulvesterant can slightly increase the chances of a blood clot. A clot can cause symptoms such as pain, redness and swelling in a leg, breathlessness and chest pain. Contact your doctor straight away if you have any of these symptoms. A blood clot is serious but your doctor can treat it with drugs that thin the blood. Your doctor or nurse can give you more information
Vaginal bleeding or discharge
Occasionally women may have some vaginal bleeding. This usually happens in the first few weeks of treatment. It is rare and usually happens when you change from another hormonal therapy to fulvesterant. If it continues for more than a few days tell your doctor or breast care nurse.
Another uncommon side effect is a white vaginal discharge or sometimes vaginal thrush. Tell your doctor if you have this.
Always let your doctor or nurse know about any side effects you have, as there are usually ways in which they can be controlled or improved.
Other information about fulvestrant
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Delaying an injection
Occasionally delaying an injection by a day or two won’t make a great difference. But it’s important to make sure you have your injections every month as prescribed.
If you’re admitted to hospital for a reason not related to the cancer, it’s important to tell the doctors and nurses looking after you that you are having hormonal treatment. Tell them the name of your cancer specialist so that they can ask for advice.
Fulvestrant 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 and herbal drugs.
Because fulvesterant is given by injection into the muscle, it should not be taken if you are on blood thinning drugs (anticoagulants) such as warfarin.
Medical or dental treatment
If you need to go into hospital for any reason other than cancer, always tell the doctors and nurses that you are taking fulvestrant. Explain you are taking hormonal therapy that no one should stop or restart without advice from your cancer doctor. Tell them the name of your cancer doctor so they can ask for advice.
Always tell your dentist you are taking fulvestrant.
The information in this secition has been produced in accordance with the following sources and guidelines:
electronic Medicines Compendium (eMC). www.medicines.org.uk (accessed May 2014).
Sweetman, et al. Martindale: The Complete Drug Reference. 37th edition. Pharmaceutical Press. 2011.
If you’d like further information on the sources we use, please feel free to contact us.
With thanks to Kavita Kantilal, Advanced Pharmacist, who reviewed this edition.
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