Pemnat 500mg Injection (Pemetrexed)

Pemnat 500mg Injection contains pemetrexed, an antifolate cytotoxic chemotherapy medicine mainly used in nonsquamous non-small-cell lung cancer (NSCLC) and malignant pleural mesothelioma. It works by inhibiting folate-dependent enzymes needed for nucleotide production, disrupting DNA/RNA synthesis.

A defining safety requirement is folic-acid and vitamin B12 supplementation, which reduces severe hematologic and gastrointestinal toxicity without reducing anticancer activity. Pemetrexed injection is usually avoided when creatinine clearance is below 45 mL/min because renal impairment can cause excessive exposure.

Pemetrexed is administered in the following conditions:

• Nonsquamous non-small cell lung cancer (NSCLC)
  
• Malignant pleural mesothelioma

In the case of NSCLC, pemetrexed 500mg injection can be administered in combination with platinum-based chemotherapeutic drugs and pembrolizumab as a first-line therapy for metastatic disease. The medicine can be used as maintenance therapy in cases when it is initially administered along with platinum in a selected patient population or alone after the use of previous chemotherapy. In the case of malignant pleural mesothelioma, which is unresectable, the combination of pemetrexed 500mg and cisplatin is preferred.

Pemetrexed 500mg injection inhibits multiple enzymes that the cancer cells use to synthesize DNA and RNA. Once in the cells, the Pemnat 500mg Injection gets converted into metabolites that will inhibit thymidylate synthase, dihydrofolate reductase, and glycinamide ribonucleotide formyltransferase. Consequently, this leads to the depletion of essential substrates required for the synthesis of nucleic acids.

Mesothelioma pivotal trial: Pemetrexed injection along with cisplatin showed better results in survival rate than those using cisplatin alone in malignant pleural mesothelioma.

PARAMOUNT: The maintenance treatment with Pemnat 500mg injection after pemetrexed-cisplatin induction in nonsquamous non-small cell lung cancer was more effective.

KEYNOTE-189: The addition of pembrolizumab to Pemnat 500mg injection and platinum in the treatment of metastatic nonsquamous non-small cell lung cancer improved survival in the studied patients.​

Certain side effects are possible when taking the pemetrexed 500mg injection, which can vary from minor ones to those that require medical intervention. However, this is where routine monitoring plays an important role.

Common side effects

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

Serious side effects

• Severe myelosuppression/infection
  
• Renal toxicity
  
• Severe skin reactions
  
• Pneumonitis
  
• Radiation recall
• Severe GI toxicity without supplementation

Important: These are only general references to be used when giving treatments. The physician will prescribe the proper dosage, frequency, interaction with other drugs, adjustment of dosage because of renal or hepatic dysfunction, and management of adverse effects depending on the patient's status.

If an infusion is missed, contact the oncology department but do not reschedule yourself. Continue folic acid unless instructed otherwise.

• Creatinine clearance must be measured periodically to confirm the ability to administer the drug Pemnat 500mg injection without risk.
  
• Blood cell count should be assessed for low red blood cells, low white blood cells, or low platelets.
  
• The intake of folic acid and vitamin B12 should be reviewed to ensure that patients have adequate supplementation.
  
• Liver function may be tested where necessary for safety monitoring purposes.
  
• New or increased skin reactions, coughing, trouble breathing, or other symptoms involving lungs must be reported immediately.
  

• Current Alimta/pemetrexed prescribing information https://www.accessdata.fda.gov/drugsatfda_docs/label/2011/021462s033lbl.pdf​
  
• Vogelzang NJ, et al. Pemetrexed/cisplatin in mesothelioma https://pubmed.ncbi.nlm.nih.gov/12860938/​
  
• Paz-Ares L, et al. PARAMOUNT https://pubmed.ncbi.nlm.nih.gov/23835707/​
  
• Gandhi L, et al. KEYNOTE-189. NEJM https://www.nejm.org/doi/full/10.1056/NEJMoa1801005​
  
• National Cancer Institute. Pemetrexed. NCI Drug Dictionary https://www.cancer.gov/publications/dictionaries/cancer-drug/def/pemetrexed-disodium​