Methotrexate
[CAS# 59-05-2]

Identification

• Classification: API >> Antineoplastic agents >> Antimetabolite antineoplastic
• Name: Methotrexate
• Synonyms: (+)-Amethopterin; (+)-4-Amino-10-methylfolic acid; N-(p-(((2,4-Diamino-6-pteridinyl)methyl)methylamino)benzoyl)-L-glutamic acid
• Molecular Formula: C₂₀H₂₂N₈O₅
• Molecular Weight: 454.44
• Protein Sequence: XE
• CAS Registry Number: 59-05-2
• EC Number: 200-413-8
• SMILES: CN(CC1=CN=C2C(=N1)C(=NC(=N2)N)N)C3=CC=C(C=C3)C(=O)N[C@@H](CCC(=O)O)C(=O)O

Properties

• Density: 1.5±0.1 g/cm³, Calc.^*
• Melting point: 195 °C
• Index of Refraction: 1.738, Calc.^*
• Water solubility: Insoluble. <0.1 g/100 mL at 19 °C

Safety Data

• Hazard Symbols: GHS05;GHS07;GHS08 Danger
• Risk Statements: H301-H315-H319-H340-H360
• Safety Statements: P203-P264-P264+P265-P270-P280-P301+P316-P302+P352-P305+P351+P338-P318-P321-P330-P332+P317-P337+P317-P362+P364-P405-P501

Hazard Classification

Hazard	Class	Category Code	Hazard Statement
Acute toxicity	Acute Tox.	3	H301
Skin irritation	Skin Irrit.	2	H315
Eye irritation	Eye Irrit.	2	H319
Reproductive toxicity	Repr.	1B	H360
Germ cell mutagenicity	Muta.	1B	H340
Germ cell mutagenicity	Muta.	2	H341
Specific target organ toxicity - single exposure	STOT SE	3	H335
Carcinogenicity	Carc.	2	H351
Reproductive toxicity	Repr.	1A	H360
Eye irritation	Eye Irrit.	2A	H319
Acute toxicity	Acute Tox.	3	H311
Acute toxicity	Acute Tox.	3	H331
Reproductive toxicity	Repr.	2	H361

• Transport Information: UN 1544

Discovery and Applications

Methotrexate is a well-known chemical compound that has played a pivotal role in the treatment of various medical conditions, particularly in oncology and immunology. It is classified as an antimetabolite and folic acid antagonist, which allows it to interfere with DNA synthesis, repair, and cellular replication. The discovery of methotrexate dates back to the 1940s when it was first synthesized as part of research on folic acid analogs. Researchers were seeking compounds that could inhibit the activity of dihydrofolate reductase, an enzyme crucial for the synthesis of nucleotides, thus slowing down the rapid division of cancer cells.

Initially, methotrexate was investigated for its potential to treat leukemia, a malignancy characterized by the uncontrolled growth of white blood cells. In the 1950s, its use was expanded to treat a wide range of cancers, including breast cancer, osteosarcoma, and non-Hodgkin lymphoma. Methotrexate works by inhibiting dihydrofolate reductase, leading to a reduction in the availability of tetrahydrofolate, which is necessary for the synthesis of purines and thymidylate. This results in the inhibition of DNA replication and ultimately the death of proliferating cells, particularly those of rapidly dividing tumors.

Beyond its use in cancer therapy, methotrexate has been widely employed in the treatment of autoimmune diseases. These include rheumatoid arthritis, psoriasis, and Crohn’s disease, where its ability to suppress the immune system proves beneficial. By inhibiting the proliferation of immune cells, methotrexate can reduce inflammation and slow the progression of these chronic conditions. In autoimmune diseases, methotrexate helps to modulate the immune response by inhibiting the production of inflammatory cytokines and promoting the apoptosis of activated T cells.

Methotrexate is typically administered either orally or by injection, depending on the condition being treated. While the drug has proven to be highly effective, its use is often accompanied by side effects. These may include nausea, liver toxicity, and bone marrow suppression, particularly at higher doses used in cancer therapy. Consequently, patients undergoing methotrexate treatment are carefully monitored for adverse effects, and the drug is often used in conjunction with folic acid supplements to mitigate some of the side effects.

Over the years, methotrexate has been extensively studied, and its mechanisms of action have become well understood. It has paved the way for the development of newer antimetabolites and targeted therapies that continue to shape modern cancer and autoimmune disease treatments. The compound's discovery and ongoing application in medicine exemplify the impact of chemical research in improving patient outcomes and advancing therapeutic strategies in both cancer care and immunology.

References

2025. Core-shell structured magnetite carboxymethyl cellulose for cervical cancer treatment by maintaining methotrexate serum concentration. International Journal of Biological Macromolecules.
DOI: 10.1016/j.ijbiomac.2024.137832

2025. Intradermal implantation of methotrexate-loaded puerarin-gelatin hydrogel via bubble-generating microneedles for psoriasis treatment. International Journal of Biological Macromolecules.
DOI: 10.1016/j.ijbiomac.2024.138201

2024. Codelivery of metformin and methotrexate with optimized chitosan nanoparticles for synergistic triple-negative breast cancer therapy in vivo. International Journal of Pharmaceutics, 666.
DOI: 10.1016/j.ijpharm.2024.124897