Digoxin, a cardenolide strongly implicated in anti-cancer therapeutics, is metabolized to inactive dihydrodigoxin by Eubacterium lentum, commonly found in gut flora. We present here the initial stages in the development of a clinical mass spectrometry method for simultaneously measuring digoxin and dihydrodigoxin, an approach that could potentially identify cancer patients that metabolize digoxin to a lesser or greater extent. This test could guide clinicians to maximize the effectiveness of cancer treatment using cardenolides. The method could readily be translated to quantification of endogenous mammalian cardenolides, which also have potent anti-cancer properties, and for which no clinical assay is available. |
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