This module will introduce the third countermeasure, Prussian blue insoluble, which will be referred to simply as Prussian blue, and discuss its indications, administration, adverse effects, and special considerations. Afterwards, there is the option to apply what you have learned within a case study.

[Description]

Prussian blue is a decorporation agent for radioactive cesium and thallium. Prussian blue reduces radiation exposure by binding to and enhancing elimination of these radioisotopes through the gastrointestinal (GI) tract, and preventing their re-absorption into the body. Once taken, Prussian blue is not absorbed in the GI tract and remains in the gut lumen where it is available to bind cesium or thallium as they undergo enterohepatic circulation.

Similar to other countermeasures, Prussian blue is only effective for cesium and thallium, and does not work for other radionuclides, nor does it repair radiation damage that has already occurred.

[Availability]

Prussian blue comes in 500 mg, blue capsules, and is kept in some state and federal stockpiles for eventual distribution during a radiation emergency. It is a prescription medication that will be provided by public health officials or medical personnel after an emergency occurs.

[Indication]

Use of Prussian blue is indicated when individuals have been internally contaminated with a significant dose of radioactive cesium or thallium. When there is clinical suspicion of internal contamination, an exposure evaluation will be necessary to determine the amount of internal contamination and corresponding radiation dose.

Treatment with Prussian blue should begin as soon as warranted, but even delayed treatment can be beneficial.

Clinical decision guides, or CDGs, can also help determine when Prussian blue is indicated. CDGs are discussed in another section of this training module.

Prussian blue is FDA-approved for treatment of adults and children ages 2 and older. At this time, studies have not determined a safe dose for individuals younger than two years old; however, it may still be used under an Emergency Use Authorization if granted.

[Dosing and Administration]

Prussian blue is given orally, usually as a capsule, although the capsule may be opened and added to food or liquid for easier administration.

Adults and adolescents, ages 12 years and older, should be given:

• 3g of Prussian blue by mouth, three times per day

Children ages 2-12 years old should be given:

• 1g of Prussian blue by mouth, three times per day

Again, safe treatment with Prussian blue has not been established for individuals younger than two years old, but it may still be used under an Emergency Use Authorization if granted by the FDA at the time of an incident.

For patients who are unable to swallow, Prussian blue can be administered via nasogastric or orogastric tubes, or any other device that can deliver the medication to the GI tract.

Treatment with Prussian blue is recommended for a minimum of 30 days.

[Monitoring and Follow-up]

When possible, obtain baseline blood and urine samples (including CBC with differential, serum electrolytes and renal function, urinalysis and blood and urine radiobioassays) before initiating treatment. Prussian blue is known to cause hypokalemia so special attention should be paid to serum potassium levels and care should be taken when treating patients with pre-existing cardiac arrhythmias or electrolyte disorders.

During the course of treatment, samples of blood, urine, or feces may be collected to establish the effectiveness of treatment and the amount of radioactivity present. Testing for residual internal contamination should occur on a regular basis to determine when treatment can be terminated.

[Adverse effects]

Individuals that receive Prussian blue should also be monitored for allergic and other adverse reactions.

Adverse effects from treatment with Prussian blue are more common at higher doses, and include upset stomach and constipation. These symptoms can be managed in part by adding fiber to the diet. Hypokalemia is also known to occur during treatment with Prussian blue, but most reported cases have been asymptomatic.

For individuals who open Prussian blue capsules for administration in food or drink, cosmetic effects include staining of the mouth and teeth. All patients taking Prussian blue should expect blue discoloration of their stool.

[Contraindications]

There are no known contraindications for Prussian blue treatment.

[Special Considerations]

Clinicians and public health officials should educate their staff and patients that Prussian blue artist's dye is not the same chemical as Prussian blue insoluble, and should not be taken in an effort to treat internal contamination. Only FDA-approved forms of Prussian blue should be used.