Evaluation of Serum Methotrexate Level by Using Chemiluminescent Microparticle Immuno Assay (CMIA)

Abstract

Methotrexate (MTX) plays important treatment modalities for several paediatric cancers. Several automated binding assays and chromatographic methods was developed for estimating Methotrexate levels in serum and these methods are time consuming & utility of these methods in hospital set up is minimum. The ARCHITECT Methotrexate Assay by Chemiluminescent Microparticle Immuno Assay (CMIA) technology offers a sensitive & rapid estimation of Methotrexate in serum samples. So aim of this study is to evaluate the performance of ARCHITECT Methotrexate Assay kit in Chemiluminescent Microparticle Immuno Assay (CMIA) technology and to determine the level of serum methotrexate after 48 hours of Methotrexate infusion. ARCHITECT Methotrexate Assay kit was validated as per U.S Food and Drug Administration (USFDA) Bio analytical guidelines. The linearity was found to be in the range of 0.02–1.49 μmol/L with R2 0.99. The ARCHITECT Methotrexate assay showed a maximal Limit Of Detection of 0.0060 μmol/L. The Limit of quantification was found to be 0.04 μmol/L. Recovery of the sample was found to be 98.9 %. The intraday precision study showed a C.V. of 4.48 % at the lowest level and 3.83 % at the highest level where as interday precision study showed a C.V. of 2.14 % at the lowest level and 2.89 % at the highest level. The mean concentration of serum MTX after 48 hours of High Dose Methotrexate Infusion was found to be 0.487±0.357 μMol/L. The ARCHITECT assay is suitable for monitoring serum Methotrexate and showed satisfactory performance in the analysis of low concentrated samples.