Methotrexate is a potent chemotherapy agent and disease-modifying antirheumatic drug (DMARD) used primarily in the treatment of various cancers, including leukemia, lymphoma, and solid tumors, as well as autoimmune conditions like rheumatoid arthritis and psoriasis. This injectable formulation delivers the medication directly into the bloodstream for rapid and precise therapeutic action. Methotrexate works by inhibiting dihydrofolate reductase, a critical enzyme in DNA synthesis and cell replication, making it highly effective in slowing the growth of malignant cells.