DEVELOPMENT OF GLYCOSIDE-BOUND RADIOPHARMACEUTICALS - NOVEL RADIOIODINATION METHOD FOR DIGOXIN

We combined 2-hydroxy-3-methylbenzoylhydrazide (HMBH) with glycosides as a novel method for the radioiodination of physiologically active gl ycosides. This method was tested using digoxin, which is one of the ca rdiac glycosides. A digoxin-HMBH conjugate was synthesized by periodat e cleavage of the third sugar ring, and was readily radiolabelled with Na[I-125] by the chloramine-T method. I-125 labelled digoxin-HMBH con jugate retained Na+,K+-ATPase binding in vivo and in vitro, and also r etained immunoreactivity to an anti-digoxin antibody. Thus, this I-125 labelled digoxin-HMBH conjugate represents a potential radiopharmaceu tical for Na+,K+-ATPase imaging, as well as for the radioimmunoassay o f digoxin.