An antifolate chemotherapy for some lung cancers and mesothelioma
Pemetrexed
A chemotherapy medicine used for some lung cancers and mesothelioma, given by injection.
What is Pemetrexed?
Pemetrexed is a chemotherapy medicine used to treat some types of lung cancer and mesothelioma (a cancer linked to asbestos). It is given as a drip into a vein in a cancer unit. The most important safety concern is that it lowers the blood cells made in the bone marrow, raising the risk of infection, bleeding and anaemia. To make it safer and reduce side effects, people take folic acid and have vitamin B12 injections, and a short course of a steroid is given to reduce a skin rash. Because the kidneys clear the drug, it is used with care in people with reduced kidney function, and certain painkillers (NSAIDs) need careful timing around treatment.
Education and reference only. This is a plain-language guide to Pemetrexed — it deliberately contains no doses. Doses depend on the person, the brand and the reason for treatment, and belong with your prescriber. Always check the BNF, the product labelling (SmPC) and follow medical advice.
What it is
Pemetrexed is a chemotherapy medicine of the antifolate type, meaning it interferes with the way cells use folate (a B vitamin) to grow and divide. It is used to treat certain lung cancers and mesothelioma, often alongside another chemotherapy drug. It is given by a drip into a vein, in cycles, in a specialist cancer unit. Treatment is planned and supervised by a cancer (oncology) team, and it is given together with supportive measures, including vitamin supplements and a steroid, that make it safer and better tolerated.
How it works
Pemetrexed blocks several enzymes that cancer cells need to use folate to make the building blocks of DNA. Without these, fast-dividing cancer cells cannot grow and multiply, so the cancer is held back. However, the medicine also affects healthy fast-dividing cells, particularly those in the bone marrow that make blood cells, which is why it lowers blood counts. Giving folic acid and vitamin B12 helps protect the healthy cells and reduces side effects without stopping the drug working against the cancer. Because the drug is cleared by the kidneys, kidney function affects how it is handled.
Company & origin
Originated / developed by: Specialist manufacturer.
A chemotherapy medicine used in the UK for certain lung cancers and mesothelioma, given by injection in cancer units.
Practical use
How to take Pemetrexed
General, dose-free guidance — always follow your prescriber's and the leaflet's specific instructions.
- It is given as a drip into a vein in a cancer unit, in cycles, by the oncology team.
- Take your folic acid tablets and have your vitamin B12 injections as instructed, as these reduce side effects.
- Take the short course of steroid around each cycle as directed, to reduce a skin rash.
- Avoid anti-inflammatory painkillers (NSAIDs such as ibuprofen) around treatment unless your team says it is safe, as they affect the kidneys and the drug.
- Report any fever, sore throat, unusual bruising or bleeding straight away, as these can signal low blood counts.
Weighing it up
Advantages & disadvantages of Pemetrexed
Advantages
- An effective treatment option for certain lung cancers and mesothelioma.
- Supportive vitamin supplements and a steroid make it safer and reduce side effects.
- Given in cycles in a specialist unit with close monitoring.
Disadvantages
- Lowers blood cells made in the bone marrow, raising the risk of infection, bleeding and anaemia.
- Needs folic acid, vitamin B12 and a steroid alongside it to reduce side effects.
- Cleared by the kidneys, so it needs care with kidney problems and with anti-inflammatory painkillers.
Practical use
Good to know
The most important thing to know about pemetrexed is that it lowers the blood cells made in the bone marrow, which can raise the risk of infection, bleeding and tiredness from anaemia; blood counts are checked before each cycle, and you should report any fever, sore throat, unusual bruising or bleeding promptly. To make treatment safer, you take folic acid tablets and have vitamin B12 injections, which reduce side effects, and a short course of a steroid is given around each cycle to reduce a skin rash, so it is important to take these supportive medicines as instructed. Because the kidneys clear the drug, kidney function is checked, and anti-inflammatory painkillers (NSAIDs such as ibuprofen) can affect the kidneys and the drug's clearance, so the team will tell you when these need to be avoided around treatment. Like other chemotherapy, it can cause nausea, tiredness and a temporary effect on fertility, all of which the team will discuss.
Who should not take it / use with caution
- People who have had a serious allergic reaction to pemetrexed should not have it.
- It is used with caution, or avoided, in people with significantly reduced kidney function, under specialist judgement.
- It is not used in pregnancy or breastfeeding, as it can harm the baby; effective contraception is advised.
Monitoring
- Blood counts before each cycle to check the bone marrow has recovered.
- Checking kidney and liver function during treatment.
- Reviewing side effects and how the cancer is responding over time.
Side effects
- Low blood counts, raising the risk of infection, bleeding and anaemia.
- Tiredness, nausea, vomiting or loss of appetite.
- A skin rash, which the steroid is given to reduce.
- Mouth soreness, diarrhoea or, less commonly, effects on the kidneys or liver.
Key interactions
- Anti-inflammatory painkillers (NSAIDs such as ibuprofen) can affect the kidneys and how the drug is cleared, so timing matters.
- Other medicines that affect the kidneys can change how the drug is handled.
- Tell your team about all your medicines, including over-the-counter ones and supplements.
Available as: A powder made up into a solution and given as a drip into a vein.
Answers
Pemetrexed: frequently asked questions
What is pemetrexed used for?
It is a chemotherapy medicine used to treat some types of lung cancer and mesothelioma, given as a drip into a vein in a specialist cancer unit.
Why do I need folic acid and vitamin B12?
Taking folic acid tablets and having vitamin B12 injections helps protect healthy cells and reduces side effects without stopping the drug working against the cancer.
Why is a steroid given with it?
A short course of a steroid is given around each cycle to reduce a skin rash that pemetrexed can cause.
Why must I avoid anti-inflammatory painkillers?
Anti-inflammatory painkillers (NSAIDs such as ibuprofen) can affect the kidneys, which clear pemetrexed, so your team will tell you when to avoid them around treatment.
What should I watch for between cycles?
Because it lowers blood counts, report any fever, sore throat, unusual bruising or bleeding straight away, as these can be signs of low blood cells.
The wider class
About Antifolate chemotherapy
Pemetrexed belongs to the antifolate chemotherapy class. For how the class as a whole works, its shared safety principles and monitoring, see the full guide.
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Authoritative sources
- BNF
- NICE CKS
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