FDA: Bracco CardioGen ‘Strontium Breakthrough’ Caused by User Error

The ‘strontium breakthrough’ problems leading to unexpectedly high patient radiation exposure and the July 2011 voluntary recall of Bracco Diagnostics’ CardioGen-82 PET imaging agent were probably the result of user error, the FDA has announced.

FDA officials say the nationwide study Bracco is conducting has found that, of 375 patients surveyed at 43 clinical sites, 54 patients were planned for further radiation testing because of abnormal screening test results. All 54 patients were from two clinical sites. Both sites appear to have had insufficient documentation of compliance with the CardioGen-82 labeling recommendations for strontium breakthrough testing, the agency said.

The FDA said it’s working with the manufacturer to revise the CardioGen-82 labeling to better describe how to use the generator and to implement a plan for the return of CardioGen-82 to the market. The agency added that the apparent deficiencies in Bracco’s manufacturing process identified in its July 26, 2011, Drug Safety Communication were unrelated to the patient radiation exposure problem.

“The recalled CardioGen-82 generators that were functional following shipping were tested by the manufacturer to identify potential structural or functional causes of strontium breakthrough,” FDA officials said in the statement. “None of the tested generators showed signs of breakthrough.”

Bracco voluntarily recalled the rubidium-82 generator in July 2011 when the FDA recommended its use be halted because of possible strontium isotopes “breaking through” in the generation process. The recall came in the wake of excessive radiation being detected in two patients.

The patients’ exposure came to light when they traveled to the United States and set off airport radiation alarms despite having had PET scans two and four months earlier. Rb-82 has a half-life of 75 seconds; strontium’s is 25 days.

The FDA said in July 2011 that it believed the risk of harm to be minimal, with the estimated amount of excess radiation the two patients received being similar to that of exposure to certain other types of heart scans.

In an October 17, 2011, letter to customers, Bracco said it suspected user error to have played a role and the company expected a “limited and progressive reintroduction” of CardioGen-82 PET tracer in the first or second quarter of 2012.