Liquid chromatographic analysis and preliminary pharmacokinetics of methotrexate in cancer patients co-treated with docetaxel

A new HPLC method has been developed for the quantitative determination of methotrexate (MTX) and its 7-hydroxyl metabolite-inhuman plasma. Samples we re purified by protein precipitation with acetone and methanol, and a sampl e 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 measur ement was performed at 313 nm, and the detector response was linear in a co ncentration range of 10-10 000 ng/ml. The lower limit of quantitation of-MT X 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%, respe ctively, at four concentrations analyzed in quintuplicate on four separate occasions. The assay was applied to study the effects of docetaxel co-admin istration on the pharmacokinetics and metabolism of MTX in cancer patients. (C) 1999 Elsevier Science B.V. All rights reserved.