The agency said it received reports of two patients who received more radiation than they were supposed to during a medical procedure, and that exposure was linked to the CardioGen-82. "The excess radiation was due to strontium isotopes which may have been inadvertently injected into the patients due to a 'strontium breakthrough' problem with CardioGen-82," the FDA said in a Drug Safety Communication (07/15/11).
CardioGen-82 is used in cardiac positron emission tomography (PET) scans with rubidium (Rb)-82 chloride injection. Rubidium chloride is a radioactive tracer that is used to assess blood flow through the patient's heart to monitor for blocked coronary arteries or damage to the heart muscle. Two patients who received the rubidium (Rb)-82 chloride injection from CardioGen-82 reportedly set off security scanners at the US border.
The FDA has since determined that CardioGen-82 manufacturing procedures were not adequate to ensure the generator producing Rb-82 is reliable enough to prevent strontium breakthrough. Because the components of the heart scanner used in PET have a very short half-life, the chemical must be generated at the time of each scan rather than being made ahead of time and stored until use.
"Reliable generator performance is essential to help prevent strontium breakthrough from CardioGen-82 and to prevent patients from being exposed to excess radiation," the agency noted (07/15/11).
When the FDA announced its recall, it noted that the risk of harm from the exposure was minimal but warned, "any unnecessary exposure to radiation is undesirable." Furthermore, the FDA advised that health care professionals consider other procedures for heart scans while the agency investigates the excess radiation.
Strontium-85, one of the byproducts of the process, is linked to bone marrow damage, but experts say it would take 1,000 times the patient's exposure to cause harm.
According to the Herald-Tribune (09/22/11), one patient was stranded in Canada while investigators determined why he had excess radiation in his system. The article reports that the "breakthrough" radiation was caused by devices that were used for too long because there were not replacements available.
READ MORE CARDIOGEN-82 LEGAL NEWS
According to the Herald-Tribune article, in January 2011, a manufacturing problem resulted in a shortage of the CardioGen-82. In response, Bracco extended the expiration limit to 45 days. The device linked to the two overexposed patients went into use on January 8 but the patients were not treated until mid-February, more than 40 days after the device was placed into use.