title: Development and application of a radioimmunoassay for methotrexate.
abstract: An antiserum to methotrexate has been produced in a sheep against a conjugate of ovalbumin and methotrexate (MTX) prepared using a water-soluble carbodiimide. The antibodies produced were specific for substances containing the 2,4-diamino pteridine structure. Naturally occurring folates did not interfere with the assay. A radioimmunoassay has been developed using this antiserum, which can be used to measure MTX concentrations of less than 1 ng/ml in biological samples without prior extraction. The concentrations of MTX in the blood and urine of patients following a single i.v. bolus injection and following oral administration of the drug have been measured. The published radioimmunoassays for MTX have been compared.
mesh_terms: D007106:Immune Sera; D008727:Methotrexate / Q000032:analysis* / Q000276:immunology; D010047:Ovalbumin / Q000276:immunology; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D007106:Immune Sera; D010047:Ovalbumin; D008727:Methotrexate