FDA approves first Prussian blue for treatment of radiation contamination

ROCKVILLE, MD., October 2, 2003 -- The FDA has approved a New Drug Application for Radiogardase, also known as Prussian blue, to treat people exposed to radiation contamination, due to harmful levels of cesium-137 or thallium. Radiogardase capsules contain Ferric (III) hexacyanoferrate(II).

Approval of Radiogardase is part of FDA's continuing efforts to provide the American public with medical countermeasures in the event of a terrorist attack. The approval was based on analysis of epidemiological studies and literature reporting on patients treated with Prussian blue in emergencies involving exposure to cesium-137 or thallium. Radiogardase works by increasing the rate of elimination of these substances from the body.

"FDA has taken a significant role in helping to speed the development of bioterrorism countermeasures," said FDA Commissioner, Mark B. McClellan, M.D., Ph.D. "This first NDA approval for Radiogardase is part of the FDA initiatives aimed at bringing these critically important products to fruition."

For several decades, Prussian blue has been used to enhance the excretion of cesium-137 and thallium from the body into the stool. Contamination with cesium-137 or thallium can occur through a variety of routes including ingestion, inhalation, or wounds and can cause serious illness or death when high radiation doses are absorbed and delivered to critical organs. At lower doses such contamination has been associated with the development of cancer.

Cesium-137 is widely used by industry and in medicine in a variety of devices and to treat certain cancers. Non-radioactive thallium is used in industry and as a rat poison. The radioactive form of thallium (thallium-201) is an approved drug used in small doses for medical imaging procedures. This use of radioactive thallium at low doses is very safe.

Contamination by Cesium-137 is of particular concern because of its potential use as a component of a conventional explosive device containing radioactive material, commonly called a "dirty bomb." Although this radiological dispersal device is not a nuclear bomb, it is detonated as a means to spread radioactive material and contaminate people and property.

Radiogardase is given orally. The main possible side effects are constipation and upset stomach. Treatment should begin as soon as possible after exposure to radioactive cesium or thallium. When the sources of radiation contamination are multiple or unknown, other drugs (such as potassium iodide) can be used together with Radiogardase.

The NDA for Radiogardase was sent to the agency in response to FDA's announcement in January, 2003, that Prussian blue is safe and effective, when produced under conditions specified in approved marketing applications, for the treatment of exposure to radioactive thallium, non-radioactive thallium, or radioactive cesium. The national stockpile of products for use in the event of an emergency includes stores of Prussian blue.

FDA has also determined that pentetate calcium trisodium (Ca-DTPA) and pentetate zinc trisodium (Zn-DTPA) are safe and effective, when produced under conditions specified in approved marketing applications, for treatment of contamination with radioactive isotopes of the elements plutonium, americium and curium. FDA has encouraged manufacturers to use these findings to submit marketing applications for these drug products to use as medical countermeasures.

More information about FDA's efforts to counteract bioterrorism is available at www.fda.gov/oc/opacom/hottopics/bioterrorism.html

Radiogardase is manufactured by HEYL Chemisch-pharmazeutische Fabrik GmbH & Co. KG. of Berlin, Germany.

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Posted: October 2003


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