Pharmacologic studies with radiolabeled N-trifluoroacetyladriamycin-14-valerate (AD 32). Comparison of total anthracycline fluorescence and radioactivity in mouse serum and urine.

In connection with pharmacologic studies with AD 32, isotopically-labeled drug prepared from 1-[14C]-trifluoroacetic anhydride and adriamycin-14-valerate was used to determine murine serum and urine levels of radioactivity. Other studies, performed in parallel, measured serum and urinary total fluorescence. Serum fluorescence disappeared in a biphasic pattern, with an initial rapid rate of disappearance followed by a somewhat slower phase. For the first hour, serum radioactivity levels were not significantly different than those measured by fluorescence. After this, however, serum radioactivity decayed at a much slower rate than did fluorescence. Furthermore, a large fraction of the injected radioactivity was found excreted in the urine, whereas urine accounted for only a small fraction of the fluorescence. These results suggest the formation, in part, of a hitherto unrecognized nonfluorescent metabolite, most probably N-trifluoracetyldaunosamine.