Methotrexate
Methotrexate is an antineoplastic drug and a folate antimetabolite that is widely used at intermediate and high doses for the treatment of acute leukemia, osteosarcoma, non-Hodgkin lymphoma, and several other malignant neoplasms.
High-dose methotrexate therapy requires mandatory therapeutic drug monitoring (TDM).
This is because methotrexate has significant toxicity and may cause severe kidney and liver damage, bone marrow suppression, and inflammation of the mucous membranes.
Monitoring methotrexate concentration in the blood allows for the timely detection of delayed drug elimination and helps determine individualized doses of rescue therapy with the antidote (leucovorin).