Bacq and Alexander Award Lecture - Chemical radioprotection: past, present and future prospects

Purpose: To review and evaluate the development of effective radiation protectors. Outline: Sulphydryl radioprotectors are the best radioprotectors known today. Their use encounters two great difficulties: their toxicity and the short period during which they are active. The biological response modifiers (BRM), developed mainly ill the 1990s, demonstrated some protective effects. They can also modulate radiation injury when given after irradiation. In parallel with the use of single radioprotectors, observations have been made in mice using combined treatments with BRM and other radioprotectors. Low-to-moderate doses of several radioprotective agents acting via different mechanisms markedly improved the degree of protection in rodents while maintaining toxicity within acceptable limits, but applications in man remain doubtful. Conclusions: No radioprotective drug available today has all the requisite qualities to be an ideal radioprotector. Although combinations of radioprotective drugs acting via different mechanisms markedly improve the degree of protection and keep toxicity to acceptable levels in small rodents, attempts to use such treatments in large mammals have been less successful. It is thus questionable whether chemical protection has any prospects for the future.