FU.S. Food and Drug Administration • Center for Drug Evaluation
and Research |
FU.S. Food and Drug Administration • Center for Drug Evaluation
and Research |
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Drug Information |
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Questions and Answers on Prussian Blue
The FDA has determined that the 500 mg Prussian blue capsules, when manufactured under the conditions of an approved New Drug Application (NDA), can be found safe and effective for the treatment of known or suspected internal contamination with radioactive cesium, radioactive thallium, or non-radioactive thallium. This decision is based on a careful review of published literature articles containing reports, data, and experiences of people who were exposed to high levels of thallium or cesium-137 and were treated effectively with Prussian blue. Yes. The first approval of Prussian blue, known as Radiogardase, was October 2, 2003. Radiogardase is manufactured by HEYL Chemisch-pharmazeutische Fabrik GmbH & Co. KG. Prussian blue has been used as a pigment in industry and for artists since 1704. Prussian blue has been used as a treatment to speed up the excretion of radioactive cesium or non-radioactive thallium, from the body according to studies reported in the literature. FDA wants doctors to know that Prussian blue can be used to treat contamination that may occur as a result of a routine accidental poisoning, as well as contamination associated with a terrorist event. In an effort to ensure that Prussian blue consistently meets high standards of quality, and that proper instructions for use are available with the product, FDA continues to encourage industry to file marketing applications. The FDA has encouraged manufacturers to submit applications for Prussian blue as part of our efforts to encourage the development of drug products for treatment of people exposed to harmful levels of radioactive materials and poisons and for counter-terrorism agents. We are unaware of any clinical data demonstrating the effectiveness of Prussian blue for treating patients contaminated with any other elements. When the nature of the radioactive contamination is not known, Prussian blue may be given together with other drugs, such as potassium iodide, calcium or zinc DTPA, or sodium alginate, with known effectiveness in treating contamination from other radioactive substances. Cesium is a natural metal element. Cesium-137, a radioactive form of cesium, was discovered in 1941. Cesium-137 is still widely used today by industry and the medical community. It is used in a variety of devices, and is used as a source of radiation to treat certain cancers. Cesium-137 has the potential to be included as a part of a "dirty bomb." Thallium is a natural element found in many minerals. Thallium is very toxic and different thallium compounds have a variety of uses—from rat and ant poison to the manufacture of optical glass and other industrial uses. The radioactive form of thallium (thallium-201) is approved as a radio-imaging drug used in small doses for medical procedures. This use of thallium in low doses is very safe. Exposure to a high dose of thallium generally results in severe stomach symptoms, followed by brain symptoms, and sometimes death. However, the radioactive form of thallium (thallium-201) that is used for medical purposes is used in such small amounts that exposure to high doses is unlikely. A "dirty bomb" is a conventional, not a nuclear, bomb. It does not have the destructive power of a nuclear bomb and does not involve a nuclear explosion. Dirty bombs could contain radiological materials such as radioactive cesium (cesium-137) or other radioactive elements. Such a bomb could spread radiation over a wide area causing illness and even death. Cesium-137 and thallium-201 exposure can be beneficial to certain patients in controlled settings involving limited exposure. In the medical field, cesium-137 is used as a source of radiation for treatment of various forms of cancer. Thallium-201 is used in very small doses as a radioimaging drug. However, a dirty bomb could contain large amounts of cesium-137 or other radioactive elements. Prussian blue works using a mechanism known as ion exchange. Cesium or thallium that have been absorbed into the body are removed by the liver and passed into the intestine and are then re-absorbed into the body (entero-hepatic circulation). Prussian blue works by trapping thallium and cesium in the intestine, so that they can be passed out of the body in the stool rather than be re-absorbed. If persons are exposed to radioactive cesium, radioactive thallium, or non-radioactive thallium, taking Prussian blue may reduce the risk of death and major illness from radiation or poisoning. The most commonly reported side effects are constipation and upset stomach. Prussian blue should be taken as soon as possible after exposure. However, even when treatment cannot be started right away, patients should be given Prussian blue as soon as it becomes available because it is still effective even after time has elapsed since exposure. Yes. However, in addition to the protection provided by patents issued by the U.S. Patent and Trademark Office, Prussian blue drug products approved by FDA may be protected from competition by periods of marketing exclusivity. Please refer to the guidance document issued in January 2003, on submitting a new drug application for details. The sponsor anticipates that it will have product available for
shipment approximately six to eight weeks after approval. Prussian blue is available only by prescription and should be given only under the supervision of a physician after assessing your medical condition. It is only effective to treat contamination with radioactive cesium or thallium. The dose and duration of treatment depends on the amount of contamination a person is exposed to. Therefore, this drug should be given only when the physician has determined your need for it. The U.S. government makes sure that needed medications, especially medicines that may be needed to treat a terrorist threat, are stored in sufficient quantity to provide treatment if there is an emergency.
FDA/Center for Drug Evaluation and Research |
