LUMENAL ROUTE FOR INTESTINAL RADIOPROTECTION

The intestine, being highly sensitive to radiation injury, is the limi ting factor in the delivery of abdominal and pelvic radiation. Attempt s at intestinal radioprotection have generally involved systemic admin istration of agents that are moderately toxic and that may protect the target malignancy. The lumenal route for intestinal radioprotection p rovides a high concentration at the mucosa without significant systemi c effects. This paper reviews studies of intestinal radiation radiopro tection by intralumenal agents. Our model involved irradiation of exte riorized rat small bowel containing drugs in isolated segments. Surviv ing crypts were quantitated as a measure of injury 5 days later, and t he individual segments were compared. Modest protection was found with lumenal alkalinization and with neutralization of bile salts or pancr eatic enzymes. Similar protection was identified with some nonsteroida l anti-inflammatory agents, methylprednisolone, and selected antioxida nts. Marked protection was observed with lumenal Lazaroid.