A new HPLC method has been developed for the quantitative determination of methotrexate (MTX) and its 7-hydroxyl metabolite in human plasma. Samples were purified by protein precipitation with acetone and methanol, and a sample clean-up with a mixture of n-butanol and diethyl ether. The analytes were separated on an RP Inertsil ODS-80A column and eluted in a solvent system containing 5% (v/v) tetrahydrofuran in water (pH 2.0). UV absorption measurement was performed at 313 nm, and the detector response was linear in a concentration range of 10-10 000 ng/ml. The lower limit of quantitation of MTX was 10 ng/ml using 1 ml sample aliquots. Values for accuracy and (within- run and between-run) precision were between 95.5-111% and 3.69-11.0%, respectively, at four concentrations analyzed in quintuplicate on four separate occasions. The assay was applied to study the effects of docetaxel co-administration on the pharmacokinetics and metabolism of MTX in cancer patients. (C) 1999 Elsevier Science B.V.

Docetaxel, Methotrexate
dx.doi.org/10.1016/S0378-4347(99)00387-4, hdl.handle.net/1765/66223
Journal of Chromatography B: Biomedical Sciences and Applications
Department of Medical Oncology

Sparreboom, A, Loos, W.J, Nooter, K, Stoter, G, & Verweij, J. (1999). Liquid chromatographic analysis and preliminary pharmacokinetics of methotrexate in cancer patients co-treated with docetaxel. Journal of Chromatography B: Biomedical Sciences and Applications, 735(1), 111–119. doi:10.1016/S0378-4347(99)00387-4