The US Food and Drug Administration (FDA) is looking into the risk for brain deposits with repeated use of gadolinium-based contrast agents (GBCAs) for MRI, the agency said today in a drug safety communication.
Following administration, GBCAs are mostly eliminated from the body through the kidneys. However, recent reports suggest that GBCAs can linger in the brains of patients who undergo four or more contrast MRI scans as part of management of multiple sclerosis, cancer, or other illnesses, even in those with normal kidney function, the FDA says.
It's not known whether these deposits are harmful or can lead to adverse health effects. "To date, no signs or symptoms of adverse health effects and no pathological changes have been associated with these gadolinium deposits in the brain," the FDA notes.
However, they do err on the side of caution in their recommendation. "To reduce the potential for gadolinium accumulation, health care professionals should consider limiting GBCA use to clinical circumstances in which the additional information provided by the contrast is necessary. Health care professionals are also urged to reassess the necessity of repetitive GBCA MRIs in established treatment protocols," the FDA advises.
Free Gadolinium
Early indications are that GBCAs more prone to dissociation into free gadolinium demonstrate greater brain deposition than GBCAs less prone to dissociation, the FDA says. "A study in rats performed by a GBCA manufacturer showed greater gadolinium deposition throughout the brain in rats given a linear GBCA that is known to have greater dissociation of gadolinium, compared to a macrocyclic GBCA," they point out.
Deposits of gadolinium have also been found in the brains of deceased patients who had undergone multiple contrast-enhanced MRI examinations during their lifetime, as reported by Medscape Medical News.
The FDA, along with scientists from its National Center for Toxicological Research, will study the possible safety risk of GBCA deposition. The FDA has also engaged the research community and industry to understand the mechanism of gadolinium retention and to determine whether there are any potential adverse health effects.
For now, the FDA is not requiring manufacturers to changes the labels of GBCA products.
Table. FDA-Approved GBCAs
| Brand Name | Generic Name |
| Ablavar | Gadofosveset trisodium |
| Dotarem | Gadoterate meglumine |
| Eovist | Gadoxetate disodium |
| Gadavist | Gadobutrol |
| Magnevist | Gadopentetate dimeglumine |
| MultiHance | Gadobenate dimeglumine |
| Omniscan | Gadodiamide |
| OptiMARK | Gadoversetamide injection |
| ProHance | Gadoteridol |
Healthcare professionals are asked to report adverse events or adverse effects related to the use of these products to MedWatch, the FDA's safety information and adverse event reporting program, by telephone at 1-800-FDA-1088; by fax at 1-800-FDA-0178; online at https://www.accessdata.fda.gov/scripts/medwatch/medwatch-online.htm; with postage-paid FDA form 3500, available at http://www.fda.gov/MedWatch/getforms.htm; or by mail to MedWatch, 5600 Fishers Lane, Rockville, Maryland 20852-9787.
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Cite this: Gadolinium Brain Deposits on FDA Radar - Medscape - Jul 27, 2015.
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