rituximab + methotrexate + folic acid

This is a **combination therapy** comprising rituximab, methotrexate, and folic acid, used primarily in the treatment of active rheumatoid arthritis (RA), especially in patients with an inadequate response to methotrexate alone. - **Rituximab** is a monoclonal antibody that targets CD20 on B cells, resulting in B cell depletion and decreased autoimmune activity. - **Methotrexate** is a disease-modifying antirheumatic drug (DMARD) and antifolate that inhibits dihydrofolate reductase, interfering with DNA synthesis and immune cell proliferation. - **Folic acid** is routinely given alongside methotrexate to reduce its adverse effects, particularly those related to folate antagonism such as mucositis, gastrointestinal upset, bone marrow suppression, and liver toxicity[3][4]. Clinical studies have demonstrated that rituximab in combination with methotrexate significantly improves RA symptoms compared to methotrexate alone, and the addition of folic acid supplementation helps reduce methotrexate toxicity without reducing efficacy[1][3][4].