Monitorización terapéutica de metotrexato en pacientes leucémicos mediante cromatografía líquida de alta resolución. Desarrollo, validación y aplicación clínica del método analítico

Introduction

Therapeutic drug monitoring of methotrexate (MTX) is a practice used during acute lymphoblastic leukaemias treatments in order to adjust the leucovorin rescue dose and avoid toxicity. The aim of this work was to evaluate the performance of a bioanalytical method based on liquid chromatography in the control of paediatric acute lymphoblastic leukaemia treatments.

Materials and methods

MTX plasma concentrations were evaluated in a total of 61 patients, divided in 2 groups according to the treatment: 24 h infusion and 36 h infusion. The method used 250 μL aliquots of pre-processed plasma, using a validated analytical method, in an Agilent 1260 chromatograph with a 5 μm Zorbax Eclipse XDB-C18 column (4.6 × 150 mm) and a mobile phase composed of acetonitrile and 0.05 mol/L of a sodium acetate buffer solution at pH 3.5. The detection was performed at 305 nm.

Results

The method did not show interferences by metabolites or other drugs. The lower limit of quantitation was 0.05 μmol/L. Inter- and intra-assay precision and accuracy were acceptable in the working range (0.05-5.0 μmol/L), and linear behaviour was observed. Toxic plasma levels of MTX were observed in 29.4% and 60% of the patients from 24 h infusion and 36 h infusion, respectively. Therefore, leucovorin rescue treatment was either applied earlier or reinforced.

Conclusions

The chromatography method was efficient and accessible for the therapeutic drug monitoring of MTX in paediatric patients, allowing appropriate medical decision making within a short time of analysis.