Correlation of serum methotrexate levels with drug induced side effects

Often employed in the treatment of malignancies with high cellular proliferation rates, including acute lymphoblastic leukemia, choriocarcinoma, trophoblastic tumours, and carcinomas of the breast, tongue, pharynx, and testis; and certain nonmalignant conditions like rheumatoid arthritis, psoriasis, asthma, sarcoidosis, and transplantation therapy, methotrexate is an antifolate agent. It works by inhibiting the enzyme dihydrofolate reductase. The molecule inhibits DNA synthesis by depletion of nucleotide precursors and is associated with a number of diverse side effects. The present series comprises of 4 patients: Each demonstrated significant drug-induced side effects even though their serum methotrexate levels were found to be normal.