We have developed an adriamycin-oxidized dextran conjugate (ADM-OXD) which was found to possess not only higher antitumor activity but also less animal toxicity than ADM. It appeared that improvement of the therapeutic index of ADM-OXD was due to its bio-distribution. Therefore, we examined the tissue distribution of [14C]-OXD and [14C] ADM in tumor bearing rats and mice. ADM-OXD gave much higher blood levels than ADM. It was also found that ADM-OXD was more highly concentrated in the tumor tissues than ADM in both rats and mice. However, heart tissues showed lower concentration of ADM-OXD. On the other hand, ADM-OXD tended to remain in the liver, kidney and spleen. Approximately 50% of the administered ADM-OXD was excreted into the urine within 6 hours after its administration.
