FDA Warns of Seizure Risk Connected to Multiple Sclerosis Drug

The U.S. Food and Drug Administration (FDA) recently warned doctors and consumers about a risk associated with a relatively new drug, Ampyra, used to treat multiple sclerosis (MS). Patients who are just beginning to take the drug showed an elevated risk of seizures, and patients with kidney impairments were particularly at risk. A few weeks after the FDA’s announcement, Ampyra’s manufacturer, Acorda Therapeutics, Inc., announced that the drug did not show significant improvement in MS patients over a placebo in a second study.

Ampyra is used to improve walking speed in MS patients. The FDA announced the drug’s approval on January 22, 2010, and said that Ampyra was the first prescription medication approved for this purpose. MS is a chronic disease of the central nervous system that affects about 400,000 people in the U.S. Symptoms can range from mild to debilitating, and the nature and onset of symptoms is unpredictable in any individual patient. Difficulty walking is one of the most incapacitating symptoms. Ampyra, which is a potassium channel blocker, reportedly works by improving the transmission of signals across MS-damaged nerve cells. The drug is an extended-release capsule, taken by mouth every twelve hours. In the first year of its availability, doctors prescribed it for around 46,000 patients.

At the time of its original approval, the FDA warned against doses higher than the recommended ten milligrams every twelve hours due to a risk of seizures. It issued a safety warning on July 23, 2012 based on reports of adverse events since the drug’s release. The drug has shown an elevated risk of seizures, mostly in patients with no prior history of seizures within the first few weeks after starting the medication. The FDA recommended assessments of kidney function in patients when they start taking the drug, followed by annual checkups during treatment.

The seizure risk appears to result from high levels of the drug in a patient’s blood. The body eliminates the drug through the kidneys, and this is reportedly the source of the elevated seizure risk for patients with impaired kidney function. The FDA cautions doctors to consider all possible sources of renal impairment, including not only kidney disease, but also age-related decreases in renal function that tend to begin after the age of fifty. Beyond a certain level of renal impairment, according to the FDA, the drug should not be used at all.

Acorda announced on Monday, August 13, 2012 that it had completed a post-marketing clinical study of Ampyra that did not show improvement in patients’ walking speed. The dosage administered in the trial was five milligrams every twelve hours, half the maximum recommended amount. The study was reportedly designed differently than the study that led to FDA approval. Spokespeople for the company noted that the results failed to show statistically significant results, which is different from saying the study showed the drug does not work. Whether the FDA’s announcement or the new study findings will lead to legal claims against the company remains to be seen.

The Maryland attorneys at Lebowitz & Mzhen can assist victims of pharmacy errors, who have been injured by drugs prescribed, dispensed, or administered incorrectly. Contact us today online, or call (800) 654-1949 for a free and confidential consultation to discuss your case.

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Photo credit: ‘MULTIPLE SCLEROSIS’ by NIH (National Institute of Health) [Public domain or Public domain], via Wikimedia Commons.

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