Radioprotection of mouse skin by WR-2721 in single and fractionated treatments

Abstract

The radioprotective action of WR-2721 [3-2-(2-amino propylamino)ethylphosphorothioic acid] on mouse skin has been studied using single doses, 2 and 5 fractions. Significant radioprotection was observed with 200-500 mg/kg, in animals breathing air or O2 at the time of irradiation. The degree of radioprotection increased with increasing dose, and was significantly greater in air than in oxygen, especially at low drug doses. Cumulative drug toxicity limited the fractionated treatments to lower drug doses, but the protection observed was similar to that seen with single doses at the same drug levels. The protection factors observed are lower than many published values for skin. A single protection factor cannot yet be stated for any dose of WR-2721. Local tissue oxygenation may account for some of the discrepancies in different studies.