Handling a nuclear incident: potassium iodide. (Some Regional Distribution Plans in Place).
Potassium iodide (KI) is not a substitute for knowledge about what to do in the event of a nuclear incident, stressed Dr. Jan Carney, Vermont commissioner of health. However, KI has been shown to be a safe and effective way to reduce the risk of thyroid cancer due to radioactive iodine.
In January 2002, Dr. Carney requested enough doses of KI to allow for two tablets per person within a 10-mile Emergency Planning Zone (within 10 miles of a nuclear power plant) in her state. Receipt of KI was voluntary. Her program used newspapers, presentations, Web sites, . community newsletters, and consultations to get the word out. As of last month, more than 1,100 Vermonters have requested KI, she said at the symposium, also sponsored by Johns Hopkins University.
The Calvert County Md., health department used public health nurses to distribute KI through the schools. As a result, 22,902 KI tablets were distributed to more than 2,000 households-approximately 33% of the target population within a 10-mile radius of a nuclear power plant.
But the public must be reminded not to take KI unless advised to do so by public health officials, ideally within 4 hours post exposure. Doctors should remind patients that KI only protects against radioactive iodine and not other radiation, and that KI is no substitute for other safety measures such as evacuating the endangered area, seeking indoor shelter, and avoiding consumption of contaminated food (usually milk or leafy green vegetables).
Two KI products, Thyro-Block (Wallace Pharmaceuticals) and Iosat (Anbex Inc.), are approved by the Food and Drug Administration for over-the-counter use. Per package instructions, a 130-[micro]g Iosat tablet is safe for all but babies younger than 1 year, who can safely tolerate half a tablet. But recent FDA guidance suggests smaller doses for infants and children. (See box.)
The Food and Nutrition Board of the National Academy of Sciences also has studied the tolerable upper limits of daily KI.
"These are rather conservative numbers," said Dr. John T. Dunn, professor of medicine at the University of Virginia, Charlottesville, who was involved in the effort, The panel concluded that as much as 1,100 [micro]g/day may be safe for most adults, while 300 [micro]g is a tolerable upper limit for children from birth to 8 years, and 600 [micro]g is a tolerable upper limit for children from 9 to 13 years. The exception would be people with increased iodine deficiency.
The CDC recommends a single dose of KI within the first 4 hours of exposure to radioactive iodine; the FDA guidelines suggest continued daily dose while in an exposed area.
RELATED ARTICLE: Potassium Iodide Dosage Guidance
These numbers represent the best current thinking in terms of daily dosage of potassium iodide to protect the thyroid, said Dr. David Orloff of the Food and Drug Administration. He emphasized that the overall benefits of protective KI far exceed the risks of overdosing, especially in children.
* Adults (older than 18 years): 130 mg
* Pregnant or lactating women: 130 mg
* Newborns (up to 1 month old): 16 mg
* Infants (aged 1 month to 3 years): 32 mg
* Children 3-18 years: 65 mg *
* Teens weighing more than 150 pounds should take the adult dosage.
Source: "Potassium Iodide as a Thyroid Blocking Agent in Radiation Emergencies," www.fda.gov/cder/guidance/4825fnl.htm
Patients can buy Iosat at www.anbex.com.
Information about KI is available from the FDA at www.fda.gov/cder/drugprepare/KI_Q&A.htm.
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|Publication:||Internal Medicine News|
|Date:||Apr 15, 2003|
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