2011 Nuclear Power Plant Sourcebook: Drugs for Exposure to Radioactive Iodine and Cesium - Potassium Iodide (KI) and Prussian Blue

Two drugs, potassium iodide and prussian blue, are used to treat patients exposed to radioactive iodine and cesium. This authoritative collection of official documents has complete coverage of these important drugs.

Potassium iodide is a salt, similar to table salt. Its chemical symbol is KI. It is routinely added to table salt to make it "iodized." Potassium iodide, if taken in time and at the appropriate dosage, blocks the thyroid gland's uptake of radioactive iodine and thus could reduce the risk of thyroid cancers and other diseases that might otherwise be caused by exposure to radioactive iodine that could be dispersed in a severe nuclear accident. Potassium iodide is a special kind of protective measure in that it offers very specialized protection. Potassium iodide protects the thyroid gland against internal uptake of radioiodines that may be released in the unlikely event of a nuclear reactor accident. The purpose of radiological emergency preparedness is to protect people from the effects of radiation exposure after an accident at a nuclear power plant. Evacuation is the most effective protective measure in the event of a radiological emergency because it protects the whole body (including the thyroid gland and other organs) from all radionuclides and all exposure pathways. Administering KI can be a reasonable, prudent, and inexpensive supplement to in-place sheltering and evacuation.

Since the 1960s, Prussian blue has been used to treat people who have been internally contaminated with radioactive cesium (mainly Cs-137) and nonradioactive thallium (once an ingredient in rat poisons). Doctors can prescribe Prussian blue at any point after they have determined that a person who is internally contaminated would benefit from treatment. Prussian blue will help speed up the removal of cesium and thallium from the body. Prussian blue traps radioactive cesium and thallium (mainly Tl-201) in the intestines and keeps them from being re-absorbed by the body. The radioactive materials then move through the intestines and are excreted (passed) in bowel movements. Prussian blue reduces the biological half-life1 of cesium from about 110 days to about 30 days. Prussian blue reduces the biological half-life of thallium from about 8 days to about 3 days. Because Prussian blue reduces the time that radioactive cesium and thallium stay in the body, it helps limit the amount of time the body is exposed to radiation.

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