Trimetrexate

Chemical structure of Trimetrexate

Trimetrexate is a chemotherapy drug used primarily in the treatment of Pneumocystis pneumonia (PCP) in patients with AIDS and as a second-line treatment for certain types of cancer. It is a dihydrofolate reductase inhibitor, which means it works by interfering with the folic acid pathway, crucial for the synthesis of nucleic acids in cells.

Mechanism of Action

Trimetrexate inhibits the enzyme dihydrofolate reductase (DHFR), which is necessary for the conversion of dihydrofolate to tetrahydrofolate. Tetrahydrofolate is required for the synthesis of thymidylate, a nucleotide essential for DNA replication and cell division. By blocking this pathway, trimetrexate prevents the proliferation of rapidly dividing cells, such as cancer cells and the Pneumocystis jirovecii organism.

Clinical Use

Trimetrexate is primarily used in combination with leucovorin as a rescue agent to reduce toxicity. This combination is particularly effective in treating Pneumocystis pneumonia in patients who cannot tolerate or do not respond to standard treatments like trimethoprim-sulfamethoxazole.

In oncology, trimetrexate has been investigated for use in treating various types of cancer, including colorectal cancer and non-small cell lung cancer. However, its use is limited due to the availability of more effective treatments.

Side Effects

Common side effects of trimetrexate include myelosuppression, which can lead to anemia, leukopenia, and thrombocytopenia. Other side effects may include nausea, vomiting, diarrhea, and mucositis. Due to its potential for severe toxicity, careful monitoring of blood counts and renal function is necessary during treatment.

Related Pages

• Chemotherapy
• Dihydrofolate reductase
• Pneumocystis pneumonia
• AIDS

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