Techniques for the measurement of methotrexate in biological samples.

Techniques available for the measurement of methotrexate (MTX) in biological fluids are reviewed. The importance of measuring MTX in plasma following high-dose MTX treatment is now well recognized and renewed interest in the metabolism and pharmacokinetics of the drug has prompted the development of new techniques of analysis. Results obtained with our radioimmunoassay are presented and compared with results obtained by other methods.