Radioprotective

Radioprotective describes substances or interventions that reduce tissue injury caused by ionizing radiation. The term encompasses chemical radioprotectors, physical shielding, and physiological strategies that lessen acute and late radiation effects. In medicine, radioprotective agents are studied to protect normal tissues during radiotherapy and to mitigate harm from accidental or environmental exposure.

Chemical radioprotectors include amifostine (WR-2721), a prodrug converted to the active thiol WR-1065, which scavenges free radicals and helps protect DNA. Amifostine is approved to reduce xerostomia in patients receiving radiotherapy for head and neck cancer and to protect certain normal tissues in other settings; dose-limiting toxicities include hypotension and nausea. Other pharmacologic candidates such as N-acetylcysteine, vitamin C and E, selenium, melatonin, and genistein have shown radioprotective effects in studies with varying results, but none has achieved broad clinical adoption comparable to amifostine.

Nonpharmacologic measures include shielding with protective barriers, maintaining distance from the radiation source, and minimizing exposure time. Pharmacologic thyroid protection with potassium iodide is used to block uptake of radioactive iodine after a nuclear release and requires appropriate timing and dosing.

Radioprotective research aims to improve the therapeutic ratio in radiotherapy and to protect against accidental exposure while avoiding unintended protection of malignant tissue. Ongoing work covers targeted delivery, redox biology, and safety optimization. The term also applies to protective strategies in occupational safety and spaceflight to limit radiation risks.