A nurse is reinforcing teaching to a client who is beginning methotrexate therapy for rheumatoid arthritis. Which explanation should the nurse provide about the medication's mechanism of action?

A. Methotrexate does not directly regenerate cartilage. While controlling inflammation can slow the progression of joint damage and prevent further cartilage loss, the drug does not have reparative effects on existing cartilage. Clients should not expect the medication to reverse structural joint damage. B. Methotrexate is not a traditional analgesic and does not directly block pain receptors. Pain reduction occurs indirectly as inflammation in the joints decreases due to suppression of the overactive immune response. C. Methotrexate is a disease-modifying antirheumatic drug (DMARD) that works by suppressing the immune system. In rheumatoid arthritis, the immune system mistakenly attacks the synovial tissues of the joints, causing inflammation, swelling, and pain. Methotrexate inhibits folate-dependent enzymes, which reduces the proliferation of immune cells and production of inflammatory mediators. By doing so, it slows the autoimmune attack, decreases inflammation, and helps prevent long-term joint destruction. D. Methotrexate does not stimulate red blood cell production; in fact, one of its potential adverse effects is bone marrow suppression, which can reduce red blood cells, white blood cells, and platelets. Regular laboratory monitoring is critical to detect cytopenias early.