Medication Review: What is the Mechanism of Action of Methotrexate?

July 2025

In this video, clinical pharmacist and RhAPP faculty member Danielle Gatti Palumbo breaks down the mechanism of action of methotrexate, explaining how this folate antimetabolite works to inhibit DNA synthesis, reduce inflammation, and regulate immune response.

Methotrexate is a folate antimetabolite that plays a crucial role in inhibiting DNA synthesis, repair, and cellular replication, making it a widely used treatment for autoimmune diseases and certain cancers. Its primary mechanism involves binding to and inhibiting dihydrofolate reductase (DHFR), which prevents the formation of reduced folate, a key component in DNA and RNA synthesis. This inhibition is why folic acid supplementation is recommended for patients taking methotrexate. Additionally, methotrexate blocks thymidylate synthase (TS), further disrupting purine and pyrimidine synthesis, leading to decreased cell proliferation.

Beyond its effects on cellular replication, methotrexate exerts powerful anti-inflammatory properties by interfering with dendritic cell and T-cell communication, reducing pro-inflammatory cytokines, and increasing adenosine levels at sites of inflammation. These actions help suppress immune system overactivity, making methotrexate a cornerstone therapy in conditions like rheumatoid arthritis, psoriasis, and other autoimmune diseases. Furthermore, methotrexate promotes cell apoptosis, contributing to its efficacy in disease management.

For more insights into methotrexate, its uses, and best practices for patient care, visit the RhAPP website or explore additional educational content on the RhAPP ACE App.