What is the methotrexate dosing for oncology patients?

In oncology, methotrexate is often administered in high doses for the treatment of certain types of cancer, particularly in chemotherapeutic regimens for malignancies such as leukemias and lymphomas. The rationale behind using high-dose methotrexate, typically at 40 mg/m² or higher, is to achieve concentrations in the body that are sufficient to exert a therapeutic effect against rapidly dividing cancer cells. This is particularly effective since methotrexate acts as an antimetabolite, inhibiting the enzyme dihydrofolate reductase, critical in the synthesis of nucleic acids necessary for cancer cell proliferation.

In high-dose regimes, it is also critical to manage potential toxicities, thus leucovorin rescue is often employed to mitigate the effects of methotrexate on normal tissues. The dosing may vary depending on the specific protocol and patient factors, but for many standard high-dose methotrexate protocols, the starting dose is indeed 40 mg/m² or higher.

The lower dosing options would not achieve the necessary pharmacologic effect sought in aggressive oncology treatment settings, and as such, they are typically not utilized as standard dosing in the treatment of malignancies that require methotrexate.