Certain contrast agents used in magnetic resonance imaging — gadolinium-based products made by Bayer AG, GE and others — will now carry the U.S. Food and Drug Administration's strongest, "black box" warning.
The FDA's move on Friday finalizes its announcement in May that it would add the labeling warning to the MRI contrast agents.
The final warning notes that the agent boosts the risk of a potentially fatal side effect in patients with certain kidney and liver conditions. The skin disease called nephrogenic systemic fibrosis, or NSF, can occur in some patients, the companies said in a joint letter to health-care professionals, posted on the FDA's Web site on Friday.
Such gadolinium-based imaging agents are made by Bayer AG's Bayer Schering Pharma, General Electric Co's GE Healthcare, Tyco International Ltd.'s Mallinckrodt unit, and Bracco Diagnostics Inc.
The FDA has said there have been no reports of nephrogenic systemic fibrosis among patients with normal kidney function or those with mild-to-moderate kidney insufficiency.
Agency officials first alerted doctors to the potential risk in 2006, following reports that patients who received the injectable agents developed NSF.
Although the risk of NSF from any one agent is unknown, the letter cited a study that found an estimated risk in patients with severe renal insufficiency at 4 percent.
The condition triggers thickening of the skin, organs and other tissues that makes it difficult to move and can lead to broken bones. There is no effective treatment.
Patients should be screened for kidney problems before use of such agents, the letter said, adding that the recommended dose should not be exceeded.