FDA warns against imaging med, flags Zyvox interaction

Here's another round of safety warnings from the FDA. The agency advised doctors not to use the imaging drug CardioGen-82 because of radiation risks, saying that Italian drugmaker Bracco had agreed to recall the product. Pfizer's Zyvox antibiotic, meanwhile, was flagged for potentially fatal interactions with common antidepressants.

FDA announced a review of CardioGen-82 earlier this month, the Wall Street Journal reports, saying that patients given the radioactive drug for PET imaging scans were found with detectable radiation months later. In fact, the radiation levels were strong enough to trigger radiation detectors at the U.S. border, which is how the FDA found out.

The agency said strontium isotopes used to make CardioGen-82's active ingredient, rubidium, apparently made their way into the injectable drug. Neither the agency nor Bracco have yet identified the source of the "strontium breakthrough," but FDA said that the company's manufacturing procedures aren't stringent enough to ensure that the rubidium generator works reliably.

Pfizer's high-powered antibiotic Zyvox also raised an FDA red flag. The drug can trigger a release of the neurotransmitter serotonin, making it dangerous for patients who use antidepressants that inhibit reuptake of the chemical. Excess levels of the transmitter can cause serotonin syndrome, a potentially fatal reaction. The FDA issued the drug safety announcement after deaths were reported to the adverse-event database, Reuters reports.

Selective serotonin reuptake inhibitors, or SSRIs, and related drugs are commonly used to treat depression, and they include some of the best-selling drug brands, such as Eli Lilly's Cymbalta. Other drugs that Zyvox patients may need to avoid include GlaxoSmithKline's Paxil and Wellbutrin, Lilly's Prozac, and Pfizer's Pristiq and Zoloft, as well as generic forms of these meds. In all, 29 meds are affected by the warning.

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