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FDA Drug Safety Podcast for Healthcare Professionals: Increased radiation exposure due to undetected strontium breakthrough when using CardioGen-82 for cardiac positron emission tomography (PET) scans

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Welcome, my name is Jennifer Shepherd, a pharmacist in the Division of Drug Information. On July 15, 2011, the Food and Drug Administration issued a Drug Safety Communication alerting the public; in particular, the medical imaging community; about the potential for inadvertent, increased radiation exposure in patients who underwent or will be undergoing cardiac positron emission tomography, or PET, scans with rubidium (Rb)-82 chloride injection from CardioGen-82 (manufactured by Bracco Diagnostics, Inc.). A CardioGen-82 PET scan is one of a variety of nuclear medicine scans that use radioactive drugs to evaluate the heart.  

FDA has received reports of two patients who received more radiation than expected from 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.  

At this time, FDA believes that the risk of harm from this exposure is minimal, although any unnecessary exposure to radiation is undesirable. The estimated amount of excess radiation the two patients received is similar to that other patients may receive with cumulative exposure to certain other types of heart scans; it would take much more radiation to cause any severe adverse health effects in patients. 

Healthcare professionals should closely follow the required testing and quality control procedures essential to help detect strontium breakthrough from CardioGen-82. Other types of heart scans provide information very similar to CardioGen-82 and professionals are encouraged to consider these alternatives while FDA completes its investigation of the reported cases of excess radiation exposure.  

At this time, it is unknown whether this safety issue is due to a product problem involving generator failure or due to user error, or a combination of both factors. FDA is actively investigating the root cause of this issue and will take appropriate regulatory actions as warranted. FDA will promptly notify the public when a conclusion is made. 

At this time, FDA recommends that Healthcare Professionals be aware that:

  1. While the investigation is ongoing, healthcare professionals should consider alternatives to the CardioGen-82 generator when planning nuclear medicine cardiac scans.
  2. If CardioGen-82 is used, apply special attention to the steps that help to minimize the risk for strontium breakthrough, as outlined below and in the prescribing information.
  3. They should follow the prescribing information to determine the eluate Rb-82 content and Sr-82 and Sr-85 breakthrough using an ionization chamber-type dose calibrator. This should be done daily prior to the administration of Rb-82 chloride injection to any patients.
  4. If results from strontium Sr-82/Sr-85 breakthrough testing exceed 1/10 of the specification limit, then perform the Rb-82 assay and Sr-82/Sr-85 breakthrough testing at least twice daily (i.e., the beginning and the middle of day). This additional test should be initiated on the day the Sr-82/85 levels exceed 1/10 of the specification limit and each day thereafter.
  5. The Sr-82 content must not be more than 0.02 μCi/mCi of Rb-82 at end of elution. If the Sr-82 breakthrough exceeds these specified limits, discontinue use of the generator and notify Bracco.
  6. The Sr-85 content must not be more than 0.2 μCi/mCi of Rb-82 at end of elution. If the Sr-85 breakthrough exceeds these specified limits, discontinue use of the generator and notify Bracco.
  7. They should use only additive-free Sodium Chloride Injection USP to elute the CardioGen-82 generator.  
  8. Product problems or adverse events involving CardioGen-82 should be reported to the FDA MedWatch program at www.fda.gov/medwatch. Bracco should also be notified.

Thank you for listening. The FDA is committed to keeping healthcare professionals informed of the latest safety information. Please read the Drug Safety Communication for the complete Data Summary detailing this communication. A link to this DSC can be found at www.fda.gov/Drugs/DrugSafety. If you have drug questions, you can reach us at druginfo@fda.hhs.gov.


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