Trimetrexate: Difference between revisions

Revision as of 12:01, 9 February 2025

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

References

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-{{intro}}
+== Trimetrexate ==
-Trimetrexate is a parenterally administered folate antagonist that is used as a second line therapy for severe Pneumocystis jirovecii (previously carinii) pneumonia.
-{{livtox}}
+[[File:Trimetrexate.svg|thumb|right|Chemical structure of Trimetrexate]]
-Trimetrexate therapy has been associated with transient, mild serum enzyme elevations during therapy, but has not been convincingly linked to instances of acute, clinically apparent [[liver injury]].
-{{moa}}
+'''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.
-Trimetrexate (trye" me trex' ate) is a folic acid analogue which acts as an antagonist inhibiting the enzymes involved in folate dependent synthetic pathways such as thymidine synthase, dihydrofolate reductase and glycinamide ribonucleotide formyltransferase.  Inhibition of these enzymes leads to decrease in intracellular thymidine and purine which interferes with [[RNA]] and [[DNA]] synthesis and leads to apoptotic cell death in rapidly dividing cells.  Trimetrexate is a nonclassical folate antagonist and, unlike methotrexate, is lipid soluble which leads to different pharmacokinetics and tissue distribution.  Trimetrexate was developed as an antineoplastic agent and showed some activity against breast, lung and head and neck cancer, but had difficult toxicities and never received approval for these uses in the United States.  Trimetrexate is also taken up by pathogens including Pneumocystis jirovecii where it blocks the folate dependent synthetic pathways and causes their death.  At the same time, folate being water soluble can partially block the systemic effects of trimetrexate, but is not taken up by the pathogens.  For this reason, high doses of trimetrexate combined with leucovorin “rescue” were evaluated as therapy of Pneumocystis jirovecii in patients who were resistant or intolerant of first line anti-Pneumocystis therapies.  Trimetrexate was approved for use as a second line therapy of moderate-to-severe Pneumocystis jirovecii pneumonia in immunodeficient patients in the United States in 1993.  It remains available as a second line drug for this indication, but has not been widely used.
-{{dose}}
+== Mechanism of Action ==
-Trimetrexate is available in single use vials of 25 or 200 mg as a powder for reconstitution under the brand name Neutrexin.  The recommended dose is 45 mg/m2 once daily for 21 days concurrent with leucovorin, orally or intravenously, four times daily for 24 days.
+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.
-{{se}}
+== Clinical Use ==
-When given with leucovorin, trimetrexate is well tolerated, but can cause many of the ceommon [[side effects]] of other folate antagonists such as [[fatigue]], [[nausea]], [[vomiting]], [[anorexia]], [[diarrhea]], [[alopecia]], anemia, [[neutropenia]] and rash.  Uncommon, but potentially serious adverse events include febrile [[neutropenia]], [[infections]], [[dehydration]], [[renal failure]], [[arrhythmias]] and [[peripheral neuropathy]].
+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]].
-{{cancer drugs}}
+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.
-{{coststubd}}
+== 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]]
+== References ==
+{{Reflist}}
+[[Category:Chemotherapy]]
+[[Category:Antifolates]]
+[[Category:Drugs used in chemotherapy]]