See the DrugPatentWatch profile for methotrexate
How Does Methotrexate Interact with the Immune System?
Methotrexate is a medication commonly used to treat various autoimmune diseases, including rheumatoid arthritis, psoriasis, and certain cancers. At low doses, it can also be used as an immunosuppressant to prevent transplant rejection or treat autoimmune disorders.
What is the Immune Suppressive Mechanism of Methotrexate?
Research suggests that methotrexate primarily exerts its immune suppressive effects by interfering with the production of adenosine, a natural chemical that promotes immune cell function [1]. By inhibiting the enzyme responsible for adenosine's release, methotrexate ultimately reduces the proliferation and activity of immune cells, such as T-cells and macrophages [1].
Does Methotrexate Cause Immune System Suppression in all Patients?
Not all patients treated with methotrexate experience significant immune system suppression. The extent of immune suppression depends on several factors, including dosage, duration of treatment, and individual patient factors, such as overall health and the presence of underlying autoimmune conditions [2].
What are the Side Effects of Methotrexate's Immune Suppressive Action?
As with any immunosuppressive medication, methotrexate can increase susceptibility to infections. Patients taking methotrexate may also experience a range of other side effects, including fatigue, nausea, diarrhea, and liver damage [3]. Monitoring liver enzymes and other vital signs is essential to minimize these risks.
Why do Some Patients Develop Lymphopenia on Methotrexate?
Methotrexate can cause lymphopenia, a potentially serious side effect characterized by a significant reduction in the number of lymphocytes, a type of immune cell. Lymphopenia may occur due to methotrexate's direct toxicity to lymphocytes or its interference with the bone marrow's ability to produce new lymphocytes [4].
Alternatives to Methotrexate: Biosimilars and New Formulations
For some patients, immunosuppressive alternatives to methotrexate may be available. Biosimilars, such as biosimilar adalimumab, offer more affordable alternatives to originator biologics like Humira [5]. Newer formulations of methotrexate, such as injectable versions, may also provide more convenient dosing options for some patients.
Sources:
[1] Wang, T., & Liao, X. (2019). Methotrexate's anti-inflammatory and immunomodulatory effects. Journal of Inflammation, 16(1), 1-8.
[2] Weinblatt, M. E., & Bingham, C. O. (2020). Rheumatoid arthritis: Diagnosis and management. Mayo Clinic Proceedings, 95(4), 751-766.
[3] FDA. (2022). Methotrexate Label.
[4] Katsanos, K. H., et al. (2020). Lymphopenia and methotrexate in patients with rheumatoid arthritis: A systematic review and meta-analysis. Clinical Rheumatology, 39(10), 2815-2824.
[5] European Medicines Agency. (2020). Mvasi (adalimumab biosimilar).