Summary
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 1ng/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.
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Tracey, K.J., Mutkoski, R., Lopez, J.A. et al. Radioimmunoassay for methotrexate using hydroxyethylmethacrylate hydrogel. Cancer Chemother. Pharmacol. 10, 96–99 (1983). https://doi.org/10.1007/BF00446217
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DOI: https://doi.org/10.1007/BF00446217