Alimta 500mg Injection (Pemetrexed)

Alimta 500mg Injection contains pemetrexed, an antifolate cytotoxic chemotherapy medicine used mainly in nonsquamous non-small-cell lung cancer (NSCLC) and malignant pleural mesothelioma. The medicine works by inhibiting several folate-dependent enzymes needed to make DNA and RNA.

A major safety feature of pemetrexed injection is mandatory folic acid and vitamin B12 supplementation, which reduces severe hematologic and gastrointestinal toxicity. The 500 mg vial is a supply strength rather than the patient’s fixed dose: treatment is normally calculated by body-surface area. However, kidney function is particularly important because pemetrexed 500mg is eliminated mainly through the kidneys.

Pemetrexed 500mg injection can be used in the treatment of:

• Non-squamous non-small cell lung cancer (NSCLC)
  
• Mesothelioma of the pleura

Alimta 500mg injection can be given with platinum agents for first-line therapy, in combination with pembrolizumab drugs, as maintenance therapy following the initial course of treatment, or at a later stage depending on the circumstances. Pemetrexed injection is not used for squamous NSCLC. Therefore, the choice of therapy also depends on various factors, such as EGFR, ALK, etc.

In cancer cells, pemetrexed 500mg injection is metabolized into its active forms, which inhibit the activity of various enzymes required for the synthesis of DNA and RNA. This causes a reduction in the amount of components used by cancer cells in their proliferation. As a result, the growth and multiplication of cancer cells are slowed down.

KEYNOTE-189: The combination of pemetrexed 500mg injection, pembrolizumab, and platinum chemotherapy was effective in increasing survival rates and delaying the growth of cancer cells compared to chemotherapy in patients with metastatic nonsquamous NSCLC.

PARAMOUNT: Using pemetrexed injection as maintenance therapy in addition to Alimta 500mg injection and cisplatin delayed cancer progression and increased overall survival rates.

Mesothelioma pivotal trial: Alimta 500mg and cisplatin together increased survival rates in malignant pleural mesothelioma patients compared to cisplatin alone.​

Pemetrexed 500mg injection may lead to adverse reactions; however, the intensity of the adverse reactions differs from one individual to another. Some of the common adverse reactions are

Common side effects

• Fatigue
  
• Nausea or vomiting
  
• Reduced appetite
  
• Mouth sores
  
• Anemia
  
• Neutropenia
  
• Rash
  

Serious side effects

• ​Severe myelosuppression/infection
  
• Renal toxicity
  
• Severe skin reactions
  
• Pneumonitis
  
• Radiation recall
  

Important: The dosage regimen should always be decided by the treating doctor. The strength marked on the tablet, vial, or pack of injections does not have to be the prescribed dose. One must never initiate, discontinue, divide, combine, or switch medication just because of what is written on the Internet.

If an infusion of pemetrexed 500mg Injection is delayed or missed, contact the oncology team for guidance. Do not change the treatment schedule or take an extra dose on your own. Continue taking folic acid unless the treating doctor advises otherwise.

• Function of the kidney is checked before every cycle of treatment.
  
• The level of blood cells is checked before treatment.
  
• Folic acid and vitamin B12 must be taken as suggested.
  
• Skin and breathing must be watched out for.
  
• Liver tests can be done at the discretion of the doctor.​
  

• Cohen, M. H., Johnson, J. R., Wang, Y. C., Sridhara, R., & Pazdur, R. (2005). FDA drug approval summary: pemetrexed for injection (Alimta®) for the treatment of non-small cell lung cancer. The Oncologist, 10(6), 363-368. https://pubmed.ncbi.nlm.nih.gov/15967829/​
  
• Cohen, M. H., Johnson, J. R., Wang, Y. C., Sridhara, R., & Pazdur, R. (2005). FDA drug approval summary: pemetrexed for injection (Alimta®) for the treatment of non-small cell lung cancer. The Oncologist, 10(6), 363-368. https://www.accessdata.fda.gov/drugsatfda_docs/nda/2004/021677s000_Alimta_PrntLbl.pdf​
  
• Hazarika, M., White Jr, R. M., Booth, B. P., Wang, Y. C., Lee Ham, D. Y., Liang, C. Y., ... & Pazdur, R. (2005). Pemetrexed in malignant pleural mesothelioma. Clinical cancer research, 11(3), 982-992. https://pubmed.ncbi.nlm.nih.gov/15709163/​