Pemetrexed is a chemotherapy drug that is given as treatment for some types of cancer. It is most commonly used to treat non-small cell lung cancer (NSCLC) and pleural mesothelioma. This information describes pemetrexed, how it is given and some of the possible side effects. It should ideally be read with our general information about chemotherapy and about your type of cancer, which give further information and advice.

If you have any further questions you can ask your doctor or nurse at the hospital where you are having your treatment, or speak to one of our cancer support service nurses.

Pemetrexed is a colourless fluid.

Pemetrexed may be given as a drip (infusion):

• through a fine tube (cannula) inserted into a vein
• through a central line, which is inserted under the skin into a vein near the collarbone, or into a PICC line, which is inserted into a vein in the crook of the arm.

Chemotherapy is usually given as a course of several sessions (or cycles) of treatment over a few months. The length of your treatment and the number of cycles you have will depend on the type of cancer for which you are being treated. Your nurse or doctor will discuss your treatment plan with you.

Each person’s reaction to chemotherapy is different. Many people have very few side effects with pemetrexed, while others may experience more.

We have outlined the more 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 here, please discuss them with your doctor or chemotherapy nurse.

Lowered resistance to infection Pemetrexed can reduce the production of white blood cells by the bone marrow, making you more prone to infection. This effect can begin seven days after treatment has been given and your resistance to infection usually reaches its lowest point 10–14 days after chemotherapy. Your blood cells will then increase steadily and will usually have returned to normal levels before your next cycle of chemotherapy is due.

Contact your doctor or the hospital straightaway if:

• your temperature goes above 38°C (100.5°F)
• you suddenly feel unwell (even with a normal temperature).

You will have a blood test before having more chemotherapy to make sure that your cells have recovered. Occasionally it may be necessary to delay your treatment if the number of blood cells (the blood count) is still low.

Bruising or bleeding Pemetrexed can reduce the production of platelets, which help the blood to clot. Let your doctor know if you have any unexplained bruising or bleeding, such as nosebleeds, blood spots or rashes on the skin, or bleeding gums.

Anaemia (low number of red blood cells) While having treatment with pemetrexed, you may become anaemic. This may make you feel tired and breathless. Let your doctor or nurse know if these symptoms are a problem.

Tiredness and feeling weak You may feel very tired. It is important to allow yourself plenty of time to rest.

Mouth sores and ulcers Your mouth may become sore, or you may notice small ulcers during this treatment. Drinking plenty of fluids, and cleaning your teeth regularly and gently with a soft toothbrush, can help reduce the risk of this happening. Tell your nurse or doctor if you have any of these problems as they can prescribe special mouthwashes and medicine to prevent or clear any mouth infection.

Feeling sick (nausea) and being sick (vomiting) If you feel sick, this may begin soon after the treatment is given and last for a few days. Actually being sick is unusual. Your doctor can prescribe very effective anti-sickness (anti-emetic) drugs to prevent, or greatly reduce, nausea and vomiting. If you are sick and this continues, tell your doctor. They can prescribe different anti-sickness drugs that may be more effective. Some anti-sickness drugs can cause constipation. Let your doctor or nurse know if this is a problem.

Loss of appetite You may lose your appetite during your treatment. A hospital dietitian or specialist nurse can give advice on coping with eating problems.

Diarrhoea This can usually be controlled with medicine but let your doctor know if it is severe or if it continues. It is important to drink plenty of fluids if you do have diarrhoea.

Skin changes Pemetrexed can cause a rash, which may be itchy. Your doctor can prescribe medicine to help. To help prevent or reduce skin reactions, the steroid dexamethasone may be given with each treatment. The steroid is usually taken for three days starting on the day before pemetrexed is given.

The vitamins folic acid and Vitamin B12 (also known as hydroxycobalamin) are prescribed before treatment with pemetrexed begins and are continued throughout treatment. It is very important to take these as they reduce the unwanted effects of treatment without reducing its effectiveness.

Vitamin B12 is given as an injection into a muscle, usually a week before the first treatment and after every third treatment with pemetrexed, although this may vary slightly.

Folic acid can be taken as a tablet. It is usually started a few days before the first treatment begins and then taken every day until three weeks after treatment with pemetrexed is completed.

While you are receiving pemetrexed, it is best that you do not use any folic acid supplements other than those prescribed by your cancer specialist. Some multivitamins or food supplements also contain folic acid so it’s best to check with your chemist before taking these.

Risk of blood clots Cancer can increase your risk of developing a blood clot (thrombosis), and having chemotherapy may increase this risk further. A blood clot may cause symptoms such as pain, redness and swelling in a leg, or breathlessness and chest pain. Blood clots can be very serious so it is important to tell your doctor straightaway if you have any of these symptoms. However, most clots can usually be successfully treated with drugs to thin the blood. Your doctor or nurse can give you more information.

Other medicines Some medicines can be harmful to take when you are having chemotherapy. Let your doctor know about any medications you are taking, including non-prescribed drugs such as complementary therapies and herbal drugs.

Fertility Your ability to become pregnant or father a child may be affected by taking this drug. It is important to discuss fertility with your doctor before starting treatment.

Contraception It is not advisable to become pregnant or father a child while taking pemetrexed as it may harm the developing foetus. It is important to use effective contraception whilst taking this drug, and for at least a few months afterwards. It is important to discuss this with your doctor.

This section is based on our Pemetrexed factsheet which has been compiled using information from a number of reliable sources, including:

• Martindale: the complete drug reference (35th edition), Eds. Sweetman et al, Pharmaceutical Press, 2007.
• British National Formulary (54th edition). British Medical Association and Royal Pharmaceutical Society of Great Britain, September 2007.
• The Medicines.org.uk website – www.medicines.org.uk (November 2007).
• The Chemotherapy Source Book (3rd edition), Ed. Perry, Lippincott Williams and Wilkins, 2001.

For further references, please see general bibliography.