New warnings for MRI contrast agents in patients with kidney dysfunction9/10/2010
The U.S. Food and Drug Administration is requiring changes in the drug label for gadolinium-based contrast agents (GBCAs) to minimize the risk of nephrogenic systemic fibrosis (NSF), a rare, but serious, condition associated with the use of GBCAs in certain patients with kidney dysfunction. GBCAs are intravenous drugs used in diagnostic imaging procedures to enhance the quality of magnetic resonance imaging or magnetic resonance angiography (MRA).
These label changes are intended to help ensure these drugs are used appropriately, and that patients at risk for NSF who receive GBCAs are actively monitored for the development of NSF. Symptoms of NSF include scaling, hardening and tightening of the skin; red or dark patches on the skin; and stiffness. NSF can also cause fibrosis of internal organs which may lead to death. There is no effective treatment for NSF.
NSF has not been reported in patients with normal kidney function. Patients at greatest risk for developing NSF after receiving GBCAs are those with impaired elimination of the drug, including patients with acute kidney injury or chronic, severe kidney disease. Higher than recommended doses or repeat doses of GBCAs also appear to increase the risk for NSF.
The revised labeling will enhance the safe use of GBCAs, by recommending that health care professionals:
* Not use three of the GBCA drugs--Magnevist, Omniscan, and Optimark-- in patients with AKI or with chronic, severe kidney disease. These three GBCA drugs are contraindicated in these patients.
* Screen patients prior to administration of a GBCA to identify those with AKI or chronic, severe, kidney disease.
* Use the clinical history to screen patients for features of AKI or risk factors for chronically reduced kidney function.
* Features of AKI consist of rapid (over hours to days) and usually reversible decrease in kidney function, commonly in the setting of surgery, severe infection, injury, or drug-induced kidney toxicity. Serum creatinine levels and estimated GFR may not reliably assess kidney function in the setting of AKI.
* For patients at risk for chronically reduced kidney function (such as patients over age 60 years, patients with high blood pressure, or patients with diabetes), estimate the kidney function (GFR) through laboratory testing.
* Avoid use of GBCAs in patients suspected or known to have impaired drug elimination unless the need for the diagnostic information is essential and not available with non-contrasted MRI or other alternative imaging modalities.
* Monitor for signs and symptoms of NSF after a GBCA is administered to a patient suspected or known to have impaired elimination of the drug.
* Do not repeat administration of any GBCA during a single imaging session.
In 2006, FDA alerted the public about cases of NSF reported in patients who received GBCAs. In 2007, the agency required the addition of a boxed warning about the risk of NSF to the labeling of GBCA drugs.
http://www.nephronline.com/news.asp?N_ID=4085