The Pharmacology and Clinical Use of Methotrexate

METHOTREXATE, the most widely used antimetabolite in cancer chemotherapy, has an essential role in the treatment of such diverse diseases as acute lymphocytic leukemia, non-Hodgkin's lymphoma, osteosarcoma, choriocarcinoma, head and neck cancer, and breast cancer.¹ It has also become an important therapeutic alternative in the treatment of severe psoriasis² and in the suppression of graft-versus-host disease after bone-marrow transplantation,³ as well as in the experimental treatment of various rheumatic diseases after primary therapy has failed.⁴ Through pharmacologic research we have gained an understanding of the basic steps in the action of methotrexate, including its transport across cell membranes, its intracellular.