Chemoprotection against Fractionated Radiation Exposures with WR-2721: Skin Injury

• Published in: Radiation research 1976-06, Vol.66 (3), p.499-504
• Main Authors: Echols, F. S., Yuhas, John M.
• Format: Article
• Language: English
• Subjects: Animals; Chemical hazards; Dosage; Hair; Irradiation; Male; Mice; Organothiophosphorus Compounds - therapeutic use; Physical trauma; Radiation dosage; Radiation Injuries, Experimental - prevention & control; Radiation-Protective Agents - therapeutic use; Radioprotective agents; Radiotherapy; Radiotherapy - adverse effects; Radiotherapy Dosage; Skin - injuries; Tumors
• ISSN: 0033-7587; 1938-5404
• DOI: 10.2307/3574454

These studies extend the analysis of the potential application of WR-2721 [S-2-(3-aminopropylamino)ethylphosphorothioic acid] to radiation therapy by determining the ability of the drug to protect mice against hair loss induced by multiple exposures to radiation. In the two mouse strains tested, RFM and BALB/c, the relatively low drug dose used (200 mg/kg) protected the mice against hair loss from single exposures by factors of 1.67 and 1.73. The dose necessary to produce a given level of hair loss ( ED50) increases with increasing number of fractions. The ED50 increases as $N^{0.52}$ and $N^{0.59}$ in the two strains of mice when they are not drug-treated, but as $N^{0.39}$ and $N^{0.50}$ in mice that are drug-treated. Thus, the protective effectiveness of WR-2721 decreases with increasing numbers of fractions, but the drug is still able to give a dose-modifying factor of about 1.25 when the total exposure is given as a series of 9 or 10 fractions. WR-2721 appears to offer the possibility of improving the efficiency of radiotherapy under clinical conditions.