title: Radioimmunoassay for methotrexate using hydroxyethylmethacrylate hydrogel.
abstract: A sensitive, rapid method for the measurement of methotrexate in biologic fluids has been developed using a solid-phase radioimmunoassay (RIA). Hydroxyethylmethacrylate monomer was polymerized in the presence of rabbit antimethotrexate antisera and the resultant gels lyophilized, ground to a fine powder, and aliquoted into 3-ml syringes fitted with a fritted filter disc. Control gels without incorporated antibodies did not bind radiolabeled methotrexate, whereas a dose-response curve expressing percent bound methotrexate against antiserum concentration could be readily constructed for appropriate gels. Drug concentrations of less than 1 ng/ml can be measured. The fate of a bolus IV injection of methotrexate (100 mg) into an adult female baboon was evaluated by the HEMA-RIA system and compared with a previously published enzyme assay for the drug. These studies describe a stable and efficient system for rapid separation of bound antigen by simple filtration.
mesh_terms: D000818:Animals; D000936:Antigen-Antibody Complex; D006207:Half-Life; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D008689:Methacrylates; D008727:Methotrexate / Q000097:blood*; D010215:Papio; D011092:Polyethylene Glycols; D011863:Radioimmunoassay / Q000379:methods
chemical_list: D000936:Antigen-Antibody Complex; D008689:Methacrylates; D020136:Hydrogel, Polyethylene Glycol Dimethacrylate; D011092:Polyethylene Glycols; C005044:hydroxyethyl methacrylate; D008727:Methotrexate