U.S. advisers felt MRI imaging drugs from GE Healthcare and Covidien appear to carry a higher risk of a serious skin disease in some patients than similar products, a Food and Drug Administration official said on Tuesday.

The preponderance of opinion on the panel was GE's Omniscan and Covidien's Optimark should carry a warning saying they should not be used in patients with severe kidney disease, Dr. Dwaine Rieves, the FDA's head of medical imaging and hematology products, told reporters after a panel debated the drugs' risks.

The FDA will consider the advisers' input. The agency did not ask the panel to formally vote on whether to recommend any new warnings.

All of the drugs in the family known as gadolinium-based contrast agents already carry a warning that patients are at risk for nephrogenic systemic fibrosis (NSF), which causes thickening of the skin and organs. The FDA is debating if some carry higher risks and should bear different warnings.

The products are used to help make MRI scans easier to read and have been given to millions of patients.

Covidien already voluntarily added a warning that Optimark should not be used in patients with severe kidney disease. The company said the drug, when used as directed, has an excellent risk/benefit profile.

But Dr. Eric Cantor, head of medical professional services for GE Healthcare, told the panel the idea that some GBCAs have a higher NSF risk than others remains unproven and labeling them differently could harm patients by creating a misperception of one agent being inherently safer than another.

Medicine