title: Laser differential light-scattering bioassay for methotrexate (NSC-740).
abstract: A new bioassay method utilizing laser light scattering from suspensions of drug-sensitive bacteria has been developed for the estimation of antitumor drugs in biologic samples. Changes in the light-scattering patterns of antibiotic-treated bacteria have recently been shown to provide a rapid and accurate indication of antibiotic sensitivity. Similar considerations for several antitumor drugs have shown the method capable of assaying 0.1 ml with drug concentrations as low as a few nanograms of drug per milliliter of sample. The first successful application of the methodology is described for the antitumor agent methotrexate. Studies of both drug-treated human serum specimens and dog serum levels and urinary excretion as a function of time indicate that assay results are available within 3 hours of preparing the serum. Time variations of drug serum levels and urinary excretion rates are compared via laser differential light-scattering assay, standard disc-diffusion assay, and previously published radioisotopic assays.
mesh_terms: D000818:Animals; D001681:Biological Assay / Q000379:methods*; D004285:Dogs; D004305:Dose-Response Relationship, Drug; D013293:Enterococcus faecalis / Q000187:drug effects; D005260:Female; D006801:Humans; D007834:Lasers; D008727:Methotrexate / Q000032:analysis* / Q000494:pharmacology; D012542:Scattering, Radiation
chemical_list: D008727:Methotrexate