BACKGROUND Although quinidine is known to elevate plasma digoxin concentrations, the mechanism underlying this interaction is not fully understood. Digoxin is not extensively metabolized, but it is known to be transported by the drug efflux pump P-glycoprotein, which is expressed in excretory tissues (kidney, liver, intestine) and at the blood-brain barrier. Accordingly, we tested the hypothesi...

Background—Although quinidine is known to elevate plasma digoxin concentrations, the mechanism underlying this interaction is not fully understood. Digoxin is not extensively metabolized, but it is known to be transported by the drug efflux pump P-glycoprotein, which is expressed in excretory tissues (kidney, liver, intestine) and at the blood-brain barrier. Accordingly, we tested the hypothesi...

Recent data point to the contribution of P-glycoprotein (P-gp) to digoxin elimination. On the basis of clinical observations of patients in whom digoxin levels decreased considerably when treated with rifampin, we hypothesized that concomitant rifampin therapy may affect digoxin disposition in humans by induction of P-gp. We compared single-dose (1 mg oral and 1 mg intravenous) pharmacokinetics...

We previously developed a radioimmunoassay for digoxin using an antiserum raised against digoxin 3’-hemisuccinate -bovine serum albumin. In the present study, we aimed to establish an enzyme immunoassay (EIA) for measuring serum digoxin level in patients, using digoxin 3’-hemisuccinate-β-D-galactosidase as an enzyme-labeled antigen. The developed enzyme immunoassay showed a quantification range...

This review deals briefly with the clinical pharmacology of digoxin and reviews in some depth the problems inherent in methods of digoxin measurement. Digoxin-like factors (materials that cross react in digoxin immunoassays) are discussed, and some current evidence suggesting the existence of a new hormone, endoxin (endogenous digoxin), is summarized.

the treatment of congestive heart failure and atrial fibrillation. It is important to measure digoxin in serum from digitalized patients because the therapeutic range of serum digoxin concentration is narrow. Immunoassays are routinely used for therapeutic drug monitoring (TDM) of digoxin. The antibody with cross-reactivity to metabolites of digoxin (digoxigenin bis and monodigitoxosides, digox...

THE PRESENT STUDIES INDICATE THAT ACCUMULATION OF DIGOXIN BY INTACT HUMAN ERYTHROCYTES IS THE RESULT OF TWO PROCESSES: binding of digoxin to the erythrocyte membrane and uptake of digoxin across the membrane into the cell. In contrast, accumulation of ouabain by human erythrocytes is entirely attributable to binding of this glycoside to the plasma membrane. Digoxin binding to the erythrocyte me...

This study considers the clinical manifestations and risk factors of digoxin toxicity and establishes an appropriate cut-off serum level for the diagnosis of toxicity. A retrospectivestudy of 125 hospitalized patients whose serum digoxin was assayed in 1998 was conducted. Of the 125 subjects, 42 (33.6%) were classified as having definite digoxin toxicity, 9 (7.2%) were classified as having prob...

We describe the application of the microencapsulated-antibody technique to the radioimmunoassay of digoxin in serum. Droplets of emulsified rabbit antibody are microencapsulated in a semipermeable nylon membrane by an interfacial polymerization technique. The antibody microcapsules are incubated with 125I-labeled digoxin and unlabeled digoxin for 15 min at 37 degrees C, then free and bound digo...

Plasma digoxin concentrations on emergency admission to hospital were measured by radioimmunoassay in 10I patients who had been taking chronic maintenance digoxin therapy. The mean concentration was I4I nglml. Fifty-eight patients had plasma levels outside the range o-8 to 2-0 nglml: of these, 33 patients had levels below o-8 ng/ml and may not have been given sufficient digoxin, while 25 patien...