Answer to Question #6557 Submitted to "Ask the Experts"

What are the uses of Prussian blue tablets in treatment of ingestion of ¹³⁷Cs? What are the recommended Prussian blue doses for all age categories? How do I calculate the stock of Prussian blue for a country for an emergency? What are the side effects of the Prussian blue drug? When should a doctor prescribe Prussian blue for a patient? What are the approved producing companies of the Prussian blue drug?

You will find the most authoritative information on the use of Prussian blue and the answer to many of your questions at this U.S. Food and Drug Administration (FDA) Center for Drug Evaluation and Research Web site. This includes clinical information on prior uses of Prussian blue, recommended dosing information, and side effects.

Dosing information is available there for adults and adolescents as well as for pediatric use (2-12 years old). Dosing for infants and neonates (0-2 years) has not been established. You will note that the safety and efficacy of insoluble Prussian blue and its dosing for a pediatric population was extrapolated from adult data and supported by pediatric patients who were internally contaminated and treated with Prussian blue in the 1987 Goiania accident in Brazil. (For more information about this accident, see Health Physics 60:1; 1991 issue with several articles on this accident and also Melo et al., Health Physics, 66:3; 1994 for details related to Prussian blue treatment of those patients).

The most common adverse effects of Prussian blue are constipation and upset stomach. People may also have blue feces (stool) while they are taking the drug. The drug label also states that binding to some therapeutic drugs and essential nutrients is possible and that there are anecdotal reports in the literature of asymptomatic hypokalemia and decreased bioavailability of oral tetracycline.

Regarding medical management of internally contaminated individuals, presently there is no national guidance or consensus on what internal contamination level would constitute a medically significant amount that warrants intervention. The International Commission on Radiological Protection (ICRP) Publication 96 Protecting People Against Radiation Exposure in the Event of a Radiological Attack, 2005 (paragraph 171 on page 80) states that, with the exception of potassium iodide, "therapies for internal contamination are not recommended for general population use unless intakes are high. Generally, if the intake is <1 annual limit of intake (ALI), treatment is not usually needed, and if the intake is >10 ALI, treatment is usually indicated." The ICRP 96 further states in the same paragraph: "These treatments should be under the direction of a physician experienced in these matters, and should take individual patient factors into account." In a mass casualty event, however, it is unlikely that detailed medical evaluations can be made for each person. Nevertheless, the decision to administer Prussian blue is most certainly a medical decision and needs to be made by a competent medical authority.

The decision as to the quantity of the drug to stockpile needs to be made considering several factors including the size of the population at risk and the capacity to distribute the drug and provide medical monitoring for those treated. As is the case with other types of internal contamination, the best approach is to recommend and take protective actions that eliminate or reduce the risk of contamination in the first place. Furthermore, small amounts of internal contamination do not necessarily mean that the individual will experience health problems or that he/she requires medical intervention.

Lastly, regarding approved formulations of Prussian blue in the United States, the drug marketed under brand name Radiogardas^® has been approved by the FDA. This drug is manufactured by HEYL Chemisch-pharmazeutische Fabrik GmbH & Co.

The U.S. Distributor for Radiogardas^® is Heyltex. At a Centers for Disease Control and Prevention (CDC) Web site, you will find general information about Prussian blue written for the general public.

I hope you find this information helpful. If you are a physician from outside the United States, I recommend communicating with the radiation control authorities in your country and working with them in this planning process.

Armin Ansari, PhD, CHP