Federal health regulators have approved a new gadolinium contrast agent for use in magnetic resonance angiography, or MRA. The Food & Drug Administration (FDA) chose to approve Epix Pharmaceutical’s Vasovist Injection despite the known association between gadolinium contrast dyes and a disorder called Nephrogenic Systemic Fibrosis (NSF). The FDA said a boxed warning about the risk of NSF will be included on the labeling of Vasovist.
Vasovist is the first contrast imaging agent for use in patients undergoing MRA, a minimally invasive test for examining blood vessels. Although MRA can be performed without the use of a contrast imaging agent, the FDA said Vasovist administration provides a clearer image in patients who are suspected of having blockages or other problems with the blood vessels in their abdomen or limbs. The MRA is performed using magnetic resonance imaging (MRI), which relies on magnetic fields to create highly detailed images of the inside the body.
When blood vessels are scanned using MRA without any contrast, radiologists are unable to interpret the images about 10 percent to 30 percent of the time, the FDA said. As a result, radiologists have typically used X-rays to detect blood vessel abnormalities. But this is a lengthy procedure and requires sticking a needle into an artery to inject the X-ray dye, a procedure that may result in injury to vessel walls, blood clots, allergic reactions and potential kidney damage. According to the FDA, Vasovist is injected into a peripheral vein and no artery is punctured, thus the potential risks are fewer.
However, like any gadolinium agent, Vasovist can expose people with pre-existing kidney disease to the risk of NSF. This disease first presents as a skin condition, and often patients and their doctors don’t even realize they are dealing with something extremely serious. In most people the legs are affected first, then the feet, arms and hands. In some NSF patients the trunk of the body is also affected. NSF leads to excessive formation of connective tissue in the skin and internal organs. This disease can progress to the point of causing severe stiffness in joints, and it can lead to death.
NSF has only been seen in people with pre-existing kidney disease who have been exposed to gadolinium contrast dyes. Since 2006, the FDA has issued three separate warnings about gadolinium contrast agents and their link to NSF. The agency has also required the makers of the dyes to include a black box warning on their products’ labels. The same warning will also appear on Vasovist.
Prior to the approval of Vasovist, other gadolinium contrast agents were sometimes used off-label in MRA procedures. For those gadolinium contrast dyes to be effective in an MRA, they had to be administered at three times the approved dose. If a person’s kidneys are not functioning properly, it is extremely unlikely that so much gadolinium will be eliminated from the body. That made it far more likely that a patient with pre-existing kidney disease would develop NSF if exposed to one of these agents in an MRA procedure. In fact, some of the first reports of NSF actually occurred in patients who were exposed to gadolinium during MRA.
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