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How does pemetrexed work?

Medically reviewed by Leigh Ann Anderson, PharmD. Last updated on July 19, 2023.

Official answer


Pemetrexed (brand names: Alimta, Pemfexy) is a chemotherapy medicine that works by helping to kill or slow the growth of cancer cells. Pemetrexed is classified as an antifolate and disrupts the production of folate (a B vitamin) in your body. Your body needs folate to make DNA and for cell division.

Pemetrexed works by blocking certain enzymes involved in folate metabolism and DNA synthesis, which interferes with the process needed for a cell to divide and replicate. This action can affect cancer cells and normal cells, too, which can lead to side effects.

Pemetrexed is used in the treatment of malignant mesothelioma (a form of lung cancer associated with exposure to asbestos) and locally advanced or metastatic nonsquamous non-small cell lung cancer (NSCLC).

  • It is given as an intravenous (IV) infusion into your vein over about 10 minutes.
  • You will usually receive this medicine once every 21 days (3 weeks).
  • It may be used in combination with other cancer medicines. Pemetrexed is a not a platinum-based chemotherapy but may be used in combination with cisplatin.

Is pemetrexed a chemotherapy?

Yes, pemetrexed is in the class of chemotherapy drugs known as antimetabolites. Antimetabolites interfere with enzymes or reactions that are needed for DNA synthesis. DNA tells the cell how to grow and divide, and when you interfere with it the cell dies.

Antimetabolites change DNA by replacing the actual metabolites that would normally be used. For example, antifolates like pemetrexed interfere with the use of folic acid (a B vitamin) that is required for DNA synthesis and cell division. Other chemotherapy medicines in the antifolate group include methotrexate (Trexall, Xatmep) and pralatrexate (Folotyn).

Antimetabolites can affect both cancer cell replication and normal cell replication, leading to side effects from chemotherapy. Side effects such as fatigue, nausea, loss of appetite occur commonly when pemetrexed is used alone. Other common side effects that may occur when used pemetrexed is used in combination with cisplatin include vomiting, mouth sores, sore throat, low red and white blood cell counts and constipation.

Studies have shown that when pemetrexed is used alone hair loss (alopecia) occurs in less than 6% of patients. If it used with other treatments, such as cisplatin, hair loss may be greater, in up to 12% of patients.

Complications and side effects of pemetrexed can be reduced by using folic acid and vitamin B12 supplementation. Talk to your doctor about which side effects you can expect with pemetrexed treatment and how to minimize them.

Learn More: Pemetrexed side effects (in more detail)

This is not all the information you need to know about pemetrexed for safe and effective use and does not take the place of talking to your doctor about your treatment. Review the full pemetrexed information here, and discuss this information and any questions you have with your doctor or other health care provider.

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