title: Receptor radioligand system for measuring digoxin activity.
abstract: The purpose of this study was to develop and evaluate a receptor radioligand assay (RRA) for the measurement of digoxin, its metabolites, and endoxin and to compare the results of this assay with those of a fluorescence polarization immunoassay (FPIA) for digoxin. The within-run coefficients of variations for the RRA at digoxin concentrations of 2.0 and 5.0 nmol/L were 21 and 10%, respectively. Serum samples collected from 33 volunteers (not on digoxin medication) measured in the RRA resulted in levels less than 1.23 nmol/L digoxin equivalents (1.23 nmol/L is the lower level of sensitivity for this system). Serum samples collected from 29 patients receiving digoxin for therapeutic purposes and measured in the RRA gave a mean of 3.39 nmol/L digoxin equivalents. The samples collected from the patients receiving digoxin were also measured using FPIA with a mean of 1.75 nmol/L digoxin. The interference of progesterone, 11-alpha-hydroxyprogesterone, cortisone, and six digoxin metabolites on the binding of 3H-ouabain in the RRA was also evaluated.
mesh_terms: D000818:Animals; D001667:Binding, Competitive; D001711:Biotransformation; D004077:Digoxin / Q000032:analysis* / Q000097:blood; D004285:Dogs; D006801:Humans; D066298:In Vitro Techniques; D007668:Kidney / Q000378:metabolism; D010042:Ouabain / Q000378:metabolism; D011869:Radioligand Assay; D011955:Receptors, Drug / Q000378:metabolism; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D013256:Steroids / Q000378:metabolism
chemical_list: D011955:Receptors, Drug; D013256:Steroids; C028996:cardiac glycoside receptors; D010042:Ouabain; D004077:Digoxin; D000254:Sodium-Potassium-Exchanging ATPase