Aug. 11, 2004 -- The FDA approved two drugs today designed to counteract the effects of nuclear accidents and terrorist threats, such as so-called "dirty bombs."
The drugs, pentetate calcium trisodium injection (Ca-DTPA) and pentetate zinc trisodium injection (Zn-DTPA), increase the rate of elimination of radioactive materials from the body.
Dirty bombs are explosive devices that don't pack the punch of nuclear bombs, but can spread lethal doses of radiation to surrounding areas. The FDA has determined that Ca-DTPA and Zn-DTPA are safe and effective for treating contamination within the body with radioactive substances, such as plutonium, americium, or curium.
"The approval of these two drugs is another example of the FDA's readiness and commitment to protecting Americans against all terrorist threats," says Lester M. Crawford, MD, the acting FDA commissioner.
The two drugs have been used for several decades as investigational drugs to treat patients in radiation contamination emergencies. Until today, there had been no approved drugs for the treatment of contamination with plutonium, americium, or curium.
Internal contamination with these three agents can occur through a variety of routes including ingestion, inhalation, or direct contact through wounds. The goal of treatment with Ca-DTPA and Zn-DTPA is to enhance the removal of these radioactive contaminants and therefore the risk of possible future biological effects including the development of certain cancers, which may occur years after exposure.
Release of plutonium, americium, and curium could occur from laboratory or industrial accidents, or through terrorist attacks using a dirty bomb.
Ca-DTPA and Zn-DTPA should not be given simultaneously. If both products are available, Ca-DTPA should be given as the first dose. If additional treatment is needed, treatment should be switched to Zn-DTPA. This treatment sequence is recommended because Ca-DTPA is more effective than Zn-DTPA during the first 24 hours after internal contamination. After the initial 24 hours, Zn-DTPA and Ca-DTPA are similarly effective. Ca-DTPA and Zn-DTPA are usually injected into the blood stream, however in people whose contamination is only by inhalation, Ca-DTPA or Zn-DTPA can be administered by aerosolized inhalation.
The main side effect of Ca-DTPA is the loss of certain essential nutritional metals such as zinc, which can be replaced by taking zinc supplements by mouth. Although Zn-DTPA may also decrease the levels of certain nutritional metals, the effect is less than it is with Ca-DTPA. In addition, breathing difficulties have been noted in some individuals treated by inhalation therapy with these products.