ABSTRACT
This chapter presents classification & mode of action, indications & dermatological uses, formulations/presentation, dosages & suggested regimens, baseline investigations, considerations & monitoring, contraindications, cautions, important drug interactions, adverse effects & their management, use in special situations, and essential patient information of Methotrexate (MTX). MTX is a derivative of folic acid and classified as an antimetabolite cytotoxic agent. It is a pro-drug that is actively transported into cells as MTX-monoglutamate. Free monoglutamated MTX is rapidly cleared from the serum by renal tubular filtration. In malignant disease, high dose MTX acts as a folate antagonist, competitively inhibiting dihydrofolate reductase, thimidylate synthase and other enzymes involved in de novo purine synthesis. Adenosine may be responsible for some of the adverse effects of MTX including fatigue and hepatotoxicity. Hepatotoxicity, including liver fibrosis and cirrhosis, is a recognized association with long-term MTX treatment. MTX is strictly contraindicated during pregnancy as it is both an abortifacient and teratogen.
