Pemetrexed is a chemotherapy medicine given by drip (intravenous infusion) in a hospital or clinic, usually once every three weeks. It is used for the most common form of lung cancer — non-squamous non-small cell lung cancer — either with a platinum drug (cisplatin or carboplatin) and often an immunotherapy such as pembrolizumab at the start of treatment, on its own as maintenance afterwards, or after other treatments have stopped working. It is also used, with cisplatin, for mesothelioma, a cancer of the lining of the lung.
It belongs to the antifolate group: it blocks several enzymes that cancer cells need to make the building blocks of DNA. To protect healthy cells, everyone on pemetrexed takes folic acid tablets daily and receives a vitamin B12 injection every nine weeks, starting a week before the first dose. A steroid tablet is taken the day before, of and after each infusion to prevent skin rash.
The vials (100 mg and 500 mg) are prepared by the pharmacy for infusion; the dose is calculated from your body surface area. Pemetrexed is a prescription-only medicine; a valid prescription must be provided at checkout, and it must be administered by a healthcare professional.