Cross-Reactivity of Anti-Digoxin Antibodies with Digitoxin Depends on Tracer Structure

Abstract

The most common methods for measuring digoxin concentrations in serum are immunoassays. The prerequisite for exact determination of the digoxin value is an antibody that specifically binds digoxin. Because digitoxin differs from digoxin only in the C-12 hydroxy group, it is difficult to obtain anti-digoxin antibodies that do not cross-react with this compound. During the development of a fluorescence polarization immunoassay (FPIA) for digoxin, we investigated digoxin tracers with different structures. We found that in FPIA the digitoxin cross-reactivity of an antibody could be reduced by varying the structure of the tracer molecule.

Immunoaffinity screening with capillary electrochromatography

“…Selective analysis of cardiac glycosides (e.g., digoxin and digitoxin) is important because of their clinical use for the treatment of congestive heart failure [26,27]; digoxin is one of the most commonly prescribed drugs in the United States [28,29]. Cardiac glycosides have very narrow toxic and therapeutic margins and therefore the identification and quantification of these substances is of clinical and forensic importance [27,[30][31][32]. To date, radioimmunoassays (RIAs) are the most sensitive methods and widely used [27,31,33].…”

“…Cardiac glycosides have very narrow toxic and therapeutic margins and therefore the identification and quantification of these substances is of clinical and forensic importance [27,[30][31][32]. To date, radioimmunoassays (RIAs) are the most sensitive methods and widely used [27,31,33]. RIA, however, has been reported to be nonspecific and subject to cross-reactivity with active and inactive metabolites of cardiac glycosides [28], as well as with endogenous, digoxin-like immunoreactive substances (DLIS) [27,34,35].…”