Comparative biodistribution and radioprotection studies with three radioprotective drugs in mouse tumors

The organ level biodistribution and tumor radioprotective properties of three drugs have been compared: WR-2721 (NSC 296961), WR-3689 (NSC 327729), and WR-77913 (NSC 318809). The three drugs have similar distribution patterns in normal mouse tissues. At 30 minutes after intraperitoneal injection, highest levels of 35S from radiolabeled protector are found in kidney and submandibular salivary gland, with lowest levels in brain and moderately low values in tumor and skin. Three of four tumors examined take up less WR-3689 than the other two protectors. For the three protectors, the dose modifying factors for the RIF-1 tumor irradiated in vivo and assayed in vitro are 1.5-1.7, but do not vary as predicted by differential uptake of drug into this neoplasm. In RIF-1, WR-3689 is taken up most avidly, but the three drugs tend to be equally protective.