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Accession NumberDB01157  (APRD00268)
TypeSmall Molecule
GroupsApproved, Investigational

A nonclassical folic acid inhibitor through its inhibition of the enzyme dihydrofolate reductase. It is being tested for efficacy as an antineoplastic agent and as an antiparasitic agent against pneumocystis pneumonia in AIDS patients. Myelosuppression is its dose-limiting toxic effect. [PubChem]

External Identifiers Not Available
Approved Prescription Products
NameDosageStrengthRouteLabellerMarketing StartMarketing End
Neutrexin Pws IV 25mg/vialpowder for solution25 mgintravenousMedimmune Oncology, Inc.1994-12-312007-02-21Canada
Approved Generic Prescription ProductsNot Available
Approved Over the Counter ProductsNot Available
Unapproved/Other Products Not Available
International Brands
NeutrexinNot Available
Brand mixturesNot Available
SaltsNot Available
CAS number52128-35-5
WeightAverage: 369.4176
Monoisotopic: 369.180089627
Chemical FormulaC19H23N5O3
DescriptionThis compound belongs to the class of organic compounds known as quinazolinamines. These are heterocyclic aromatic compounds containing a quianazoline moiety substituted by one or more amine groups.
KingdomOrganic compounds
Super ClassOrganoheterocyclic compounds
Sub ClassQuinazolines
Direct ParentQuinazolinamines
Alternative Parents
  • Quinazolinamine
  • Methoxyaniline
  • Methoxybenzene
  • Phenylalkylamine
  • Substituted aniline
  • Phenol ether
  • Benzylamine
  • Anisole
  • Aralkylamine
  • Secondary aliphatic/aromatic amine
  • Aniline
  • Aminopyrimidine
  • Alkyl aryl ether
  • Imidolactam
  • Benzenoid
  • Pyrimidine
  • Primary aromatic amine
  • Monocyclic benzene moiety
  • Heteroaromatic compound
  • Azacycle
  • Secondary amine
  • Ether
  • Hydrocarbon derivative
  • Primary amine
  • Organooxygen compound
  • Organonitrogen compound
  • Amine
  • Aromatic heteropolycyclic compound
Molecular FrameworkAromatic heteropolycyclic compounds
External DescriptorsNot Available
IndicationFor use, with concurrent leucovorin administration (leucovorin protection), as an alternative therapy for the treatment of moderate-to-severe Pneumocystis carinii pneumonia (PCP) in immunocompromised patients, including patients with the acquired immunodeficiency syndrome (AIDS). Also used to treat several types of cancer including colon cancer.
PharmacodynamicsTrimetrexate, a non-classical folate antagonist, is a synthetic inhibitor of the enzyme dihydrofolate reductase (DHFR). During DNA synthesis and cellular reproduction, folic acid is reduced to tetrahydrofolic acid by the enzyme folic acid reductase. By interfering with the reduction of folic acid, trimetrexate interferes with tissue cell reproduction. Generally, the most sensitive cells to the antimetabolite effect of trimetrexate are those cells which are most actively proliferating such as malignant cells, dermal epithelium, buccal and intestinal mucosa, bone marrow, fetal cells, and cells of the urinary bladder. Because the proliferation of cells in malignant tissues is greater than in most normal tissues, trimetrexate may impair the growth of the malignant tissues without causing irreversible damage to normal tissues. Due to very serious and potentially life-threatening side-effects of this drug, leucovorin must be co-administered for at least 72 hours after the last dose.
Mechanism of actionIn vitro studies have shown that trimetrexate is a competitive inhibitor of dihydrofolate reductase (DHFR) from bacterial, protozoan, and mammalian sources. DHFR catalyzes the reduction of intracellular dihydrofolate to the active coenzyme tetrahydrofolate. Inhibition of DHFR results in the depletion of this coenzyme, leading directly to interference with thymidylate biosynthesis, as well as inhibition of folate-dependent formyltransferases, and indirectly to inhibition of p.r.n. biosynthesis. The end result is disruption of DNA, RNA, and protein synthesis, with consequent cell death.
Related Articles
AbsorptionNot Available
Volume of distribution
  • 20 ± 8 L/m2
  • 36.9 ± 6 L/m2 [cancer patients]
Protein binding95% (over the concentration range of 18.75 to 1000 ng/mL)

Hepatic. Preclinical data strongly suggest that the major metabolic pathway is oxidative O-demethylation, followed by conjugation to either glucuronide or the sulfate.

Route of eliminationTen to 30% of the administered dose is excreted unchanged in the urine.
Half life11 to 20 hours
  • 38 +/- 15 mL/min/m2 [patients with acquired immunodeficiency syndrome (AIDS) who had Pneumocystis carinii pneumonia (4 patients) or toxoplasmosis (2 patients). Trimetrexate was administered intravenously as a bolus injection at a dose of 30 mg/m2/day along with leucovorin 20 mg/m2 every 6 hours for 21 days]
  • 53 +/- 41 mL/min/m2 [Cancer patients with advanced solid tumors using various dosage regimensreceiving a single-dose administration of 10 to 130 mg/m2]
  • 30 +/- 8 mL/min/m2 [Cancer patients with advanced solid tumors using various dosage regimensafter a five-day infusion]
ToxicityThe LD50 of intravenous trimetrexate in mice is 62 mg/kg (186 mg/m2). Myelosuppression is a dose-limiting toxic effect.
Affected organisms
  • Humans and other mammals
  • Pneumocystis carinii
  • Bacteria and protozoa
PathwaysNot Available
SNP Mediated EffectsNot Available
SNP Mediated Adverse Drug ReactionsNot Available
Predicted ADMET features
Human Intestinal Absorption+1.0
Blood Brain Barrier+0.9382
Caco-2 permeable+0.6393
P-glycoprotein substrateSubstrate0.5758
P-glycoprotein inhibitor INon-inhibitor0.5948
P-glycoprotein inhibitor IINon-inhibitor0.6545
Renal organic cation transporterNon-inhibitor0.7837
CYP450 2C9 substrateNon-substrate0.8668
CYP450 2D6 substrateNon-substrate0.9116
CYP450 3A4 substrateNon-substrate0.5206
CYP450 1A2 substrateNon-inhibitor0.5
CYP450 2C9 inhibitorNon-inhibitor0.7037
CYP450 2D6 inhibitorNon-inhibitor0.7397
CYP450 2C19 inhibitorNon-inhibitor0.6512
CYP450 3A4 inhibitorNon-inhibitor0.8614
CYP450 inhibitory promiscuityLow CYP Inhibitory Promiscuity0.6235
Ames testNon AMES toxic0.6339
BiodegradationNot ready biodegradable0.9968
Rat acute toxicity2.3340 LD50, mol/kg Not applicable
hERG inhibition (predictor I)Weak inhibitor0.9027
hERG inhibition (predictor II)Non-inhibitor0.6892
ADMET data is predicted using admetSAR, a free tool for evaluating chemical ADMET properties. (23092397 )
ManufacturersNot Available
Dosage forms
Powder for solutionintravenous25 mg
PricesNot Available
Patent NumberPediatric ExtensionApprovedExpires (estimated)
US6017922 No1998-05-182018-05-18Us
Experimental Properties
melting point215-217 °CPhysProp
water solubility31.4 mg/LNot Available
logP2.55HANSCH,C ET AL. (1995)
pKa8.0Not Available
Predicted Properties
Water Solubility0.0309 mg/mLALOGPS
pKa (Strongest Acidic)17.04ChemAxon
pKa (Strongest Basic)7.54ChemAxon
Physiological Charge1ChemAxon
Hydrogen Acceptor Count8ChemAxon
Hydrogen Donor Count3ChemAxon
Polar Surface Area117.54 Å2ChemAxon
Rotatable Bond Count6ChemAxon
Refractivity107.7 m3·mol-1ChemAxon
Polarizability40.24 Å3ChemAxon
Number of Rings3ChemAxon
Rule of FiveYesChemAxon
Ghose FilterYesChemAxon
Veber's RuleYesChemAxon
MDDR-like RuleYesChemAxon
Mass Spec (NIST)Not Available
Spectrum TypeDescriptionSplash Key
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, PositiveNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 10V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 20V, NegativeNot Available
Predicted LC-MS/MSPredicted LC-MS/MS Spectrum - 40V, NegativeNot Available
Synthesis Reference

Martin Stogniew, Javad M. Zadei, “Compositions comprising trimetrexate and methods of their synthesis and use.” U.S. Patent US6258821, issued January, 1974.

General ReferencesNot Available
External Links
ATC CodesP01AX07
AHFS CodesNot Available
PDB Entries
FDA labelDownload (53.3 KB)
MSDSNot Available
Drug InteractionsNot Available
Food InteractionsNot Available


Pharmacological action
General Function:
Nadph binding
Specific Function:
Key enzyme in folate metabolism. Contributes to the de novo mitochondrial thymidylate biosynthesis pathway. Catalyzes an essential reaction for de novo glycine and purine synthesis, and for DNA precursor synthesis. Binds its own mRNA and that of DHFRL1.
Gene Name:
Uniprot ID:
Molecular Weight:
21452.61 Da
  1. Bertino JR, Zhao SC, Mineishi S, Ercikan-Abali EA, Banerjee D: Use of variants of dihydrofolate reductase in gene transfer to produce resistance to methotrexate and trimetrexate. Prog Exp Tumor Res. 1999;36:82-94. [PubMed:10386066 ]
  2. Graffner-Nordberg M, Kolmodin K, Aqvist J, Queener SF, Hallberg A: Design, synthesis, computational prediction, and biological evaluation of ester soft drugs as inhibitors of dihydrofolate reductase from Pneumocystis carinii. J Med Chem. 2001 Jul 19;44(15):2391-402. [PubMed:11448221 ]
  3. Warlick CA, Diers MD, Wagner JE, McIvor RS: In vivo selection of antifolate-resistant transgenic hematopoietic stem cells in a murine bone marrow transplant model. J Pharmacol Exp Ther. 2002 Jan;300(1):50-6. [PubMed:11752096 ]
  4. Zhu WY, Bunni M, Priest DG, DiCapua JL, Dressler JM, Chen Z, Melera PW: Severe folate restriction results in depletion of and alteration in the composition of the intracellular folate pool, moderate sensitization to methotrexate and trimetrexate, upregulation of endogenous DHFR activity, and overexpression of metallothionein II and folate receptor alpha that, upon folate repletion, confer drug resistance to CHL cells. J Exp Ther Oncol. 2002 Sep-Oct;2(5):264-77. [PubMed:12416030 ]
  5. Sweeney CL, Frandsen JL, Verfaillie CM, McIvor RS: Trimetrexate inhibits progression of the murine 32Dp210 model of chronic myeloid leukemia in animals expressing drug-resistant dihydrofolate reductase. Cancer Res. 2003 Mar 15;63(6):1304-10. [PubMed:12649191 ]
  6. Polshakov VI, Birdsall B, Frenkiel TA, Gargaro AR, Feeney J: Structure and dynamics in solution of the complex of Lactobacillus casei dihydrofolate reductase with the new lipophilic antifolate drug trimetrexate. Protein Sci. 1999 Mar;8(3):467-81. [PubMed:10091649 ]
  7. Chen X, Ji ZL, Chen YZ: TTD: Therapeutic Target Database. Nucleic Acids Res. 2002 Jan 1;30(1):412-5. [PubMed:11752352 ]
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Drug created on June 13, 2005 07:24 / Updated on August 17, 2016 12:23