Tritiated Digoxin Studies in Human Subjects

Abstract

A number of publications have appeared in recent years regarding the metabolic behavior, fate, and excretion of C14-labeled digitoxin.1-8Labeled digoxin has received little attention.9-11The preparation of a C14-labeled compound has not been practical because of the expense and uncertainty of the digoxin content of digitalis glycosides. The possibility of a tritium (H3) label was explored and was found to be both cheap and practical utilizing the Wilzbach hydrogen exchange method. The present study was undertaken to study the serum levels, absorption, and excretion of tritium-labeled digoxin*in human subjects after singledose oral digitalization. Most of the metabolic studies of unlabeled digoxin12,13have revealed the presence of unchanged digoxin and metabolite B in the urine of both rats and humans. Brown and Wright14reported the presence of metabolite F in the tissue of rats. Metabolite B has not been demonstrated