Methotrexate: The DMARD for Autoimmune Diseases and Cancer
What is Methotrexate?
Methotrexate is a disease-modifying anti-rheumatic drug (DMARD) used to treat autoimmune diseases like severe active rheumatoid arthritis, Polyarticular Juvenile idiopathic arthritis (pJIA), psoriasis, and Crohn’s disease. It is also used in cancer treatment, particularly for certain types of leukemia and lymphoma.
How Methotrexate Works
Methotrexate inhibits the enzyme dihydrofolate reductase, which is necessary for DNA synthesis. It is a folate anti-metabolite that inhibits DNA synthesis, repair and cellular replication. By blocking this enzyme, Methotrexate prevents the growth of rapidly dividing cells, which is beneficial in both autoimmune diseases and cancer treatment. In arthritis and crohns disease it modulates the immune function and decreases inflammation providing relief. In Psoriasis it targets the rapidly proliferating epithelial cells in the skin.
When to Use Methotrexate
● Rheumatoid Arthritis, Polyarticular Juvenile idiopathic arthritis (pJIA): By modulating the immune function and it helps reduce joint pain and inflammation.
● Cancer Treatment: Methotrexate is used in chemotherapy regimens to treat cancers like leukemia, lymphoma, and breast cancer, gestational trophoblastic neoplasia.
● Psoriasis: It causes decrease in excessive cellular proliferation in cases of severe psoriasis that do not respond to regular medication.
Dosage
● Adult Dose for RA: Initial doses of 10 mg to 15 mg orally once a week, either orally or via injection. We can increase the dose by 5 mg every 2-4 weeks to a maximum of 20- 30 mg once weekly. Parenterally it is started with 7.5 mg once a week and gradually escalating according to the response.
● Adult Dose for Cancer: Methotrexate is used for a wide variety of cancers and its doses vary according to age, weight, type of cancer and even the body surface area. Since it is a high end immunomodulator, it is always administered under the supervision of an oncologist.
Side Effects
● Common Effects: Nausea, fatigue, mouth sores, and gastrointestinal discomfort.
● Serious Adverse Effects: Liver toxicity, bone marrow suppression, and pulmonary toxicity.
Common Indian brands: Folitrax, Biotrexate.