Digoxin radioimmunoassay

Spironolactone interferes with some digoxin radioimmunoassays, because it and its metabolites, such as canrenone and 7-alpha-thiomethylspironolactone, are... 

Spironolactone can alter the results of some digoxin radioimmunoassays, because it and its metabohtes, such as canrenone and 7-alpha-thiomethylspironolactone, are immunoreactive with some forms of antidigoxin antibody (29-31). This results in an overestimate of the true digoxin concentration, because the assay reads the interfering substances as digoxin. 

Huffman DH. The effect of spironolactone and canrenone on the digoxin radioimmunoassay. Res Commun Chem Pathol Pharmacol 1974 9(4) 787-90. 

RG Stoll, MS Christensen, E Sakmar, et al. The specificity of the digoxin radioimmunoassay procedure. Res Commun Chem Pathol Pharmacol 4 503, 1972. 

Spierto FW, Burtis CA, Bayse DD (1983) Assay manual for the quantitation of digoxin by radioimmunoassay with the candidate reference method. CDC, Atlanta, Ga. 

High Pressure Liquid Chromatography-Radioimmunoassay. In plasma digoxin and metabolites—H. A. Nelson et al., J. Chromat., 1979,163, Biomed. AppL, 5, 169-177. 

Digoxin 0.125 mg q.o.dy q.d. (daily or every other day) 0.25 mg/day 25% 100% 100% 100% In ESRD and total body clearance decreased decrease loading dose by 50% serum level 12 hr after dose is best guide to clearance use digoxin-immune antibodies to treat severe toxicity Radioimmunoassay may overestimate serum levels in uremia clearance decreased by amiodarone, spironolactone, quinidine, and verapamil hypokalemia and hvDomaanesemia enhance toxicitv NC NC Dose for GFR 10-50 ml/min... 

ST16 Cilissen, J., Hooymans, P.M. and Merkus, F.W.H.M. (1986). Modified fluorescence polarization immunoassay compared with radial partition immunoassay and a radioimmunoassay for digoxin. Clin. Chem. 32, 2100. 

NP Kubasik, NS Norkus, HE Sim. Comparison of commercial kits for radioimmunoassay II. The radioimmunoassay of serum digoxin using iodinated tracer. Clin Biochem 7 307, 1974. 

AA MacKinney Jr, GH Burnett, RL Conklin, GW Wasson. Comparison of five radioimmunoassays and enzyme bioassay for measurement of digoxin in blood. Clin Chem 21 857, 1975. 

TW Smith, VP Butler, E Haber. Determination of therapeutic and toxic serum digoxin concentrations by radioimmunoassay. N Engl J Med 281 1212, 1969. 

PH Hinderling, et al. Comparative in vivo evaluation of a radioimmunoassay and a chromatographic assay for the measurement of digoxin in biological fluids. J Pharm Sci 75 517, 1986. 

S Mahmod, et al. Radioimmunoassay of salivary digoxin by simple adaptation of a kit method for serum digoxin—Saliva serum ratio and correlation. Ther Drug Monit 9 91, 1987. 

ER Garrett, PH Hinderling. Pharmacokinetics of beta methyl digoxin in healthy humans part 4 comparisons of radioimmunoassays total radioactivity and specific assays of beta methyl digoxin and digoxin in plasma. J Pharm Sci 66 806, 1977. 

Samples from patients receiving digoxin therapy were analyzed by the heterogeneous immunoassay LCEC method. Samples were diluted 5/1 with pooled human plasma in order to eliminate an observed antibody matrix effect. Digoxin standards in pooled human plasma were treated similarly and a standard curve constructed. Digoxin levels in patient samples were determined by reference to the standard curve. The values obtained for the samples by the electrochemical enzyme immunoassay method were compared to those obtained by radioimmunoassay. The results for the 54 samples analyzed are presented in Fig. 8. A good correlation was obtained between the two methods (r = 0.93). 

ECG effects T wave diminished in amplitude or inverted, P-R interval prolonged, Q-T interval shortened. Tests for serum digoxin levels may be altered by electrolyte imbalance, renal impairment, age, thyroid disease, other drugs, or substances in the body which imitate digoxin in radioimmunoassay. 

Inhibition of ouabain binding to membrane Na, K -ATPase and cross-reactivity with digoxin antibody in a radioimmunoassay from a pleurisy root aqueous extract were observed in vitro (Longerich et al. 1993). 

Weiler, E.W., and M.H. Zenk. 1976. Radioimmunoassay for the determination of digoxin and related compounds in Digitalis lanata. Phytochemistry 15(10) 1537-1545. 

Although the method is capable of giving the absolute quantification of both glycosides separately, at this stage we were only concerned with the relative concentrations of dihydrodigoxin and digoxin, the concentration of the latter being measured absolutely by radioimmunoassay. 

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