Antineoplastic activity and pharmacokinetics of adriamycin and daunomycin in tumor bearing mice

In C57B1/6 mice bearing the intramuscular Lewis lung carcinoma, single intravenous doses of Adriamycin showed an higher antineoplastic effectiveness on the primary tumor and its lung metastasis than equal doses of its analog Daunomycin. The in vitro cell-binding of Daunomycin to these tumor cells was higher than that of Adriamycin, but no differences in cytotoxicity were found between the two agents. Pharmacokinetic studies revealed that Adriamycin (and/or its metabolites) accumulated in the neoplastic tissue more promptly, in significantly greater quantities and for longer periods than Daunomycin. The possible importance of these findings in explaining the greater therapeutic activity of Adriamycin in experimental animals is discussed.