July 24, 2012 — The U.S. Food and Drug Administration (FDA) has published a Drug Safety Communication to warn about the risk of seizure associated with Ampyra (dalfampridine), a drug used in people with multiple sclerosis.
After reviewing the post-marketing adverse event reports, the FDA found that seizures were most common in the first few days or weeks of taking the drug. Seizures were especially common in people taking high doses of the drug, or double-dosing after accidentally missing a dose.
Ampyra (dalfampridine) is a drug that is used to help improve walking ability in patients with Multiple Sclerosis (MS), a degenerative neuro-muscular disease. The drug was developed by Acorda Therapeutics, Inc. It is also sold in Europe, under the brand-name Fampyra. It was approved in the U.S. in January 2010.
Ampyra is eliminated from the body through the kidneys, and the FDA is concerned that people with impaired kidney function may not be able to effectively remove the medication from their body. This could lead to excessively high concentrations of the drug, which may increase the risk of a seizure. Kidney impairment is very common in people over 50 years old.
When the FDA approved Ampyra, the agency was already aware that the drug could cause seizures. However, the FDA is now clarifying the warning to say that the seizures are most likely to occur within days to weeks after staring the drug for the first time. The FDA is also warning that seizures can occur in people who have no history of seizures.
The FDA is advising doctors to check a patient’s kidney function before prescribing the drug. They are warning that Ampyra should not be used in patients who have a history of seizures or moderate/severe kidney impairment. Doctors should order blood tests periodically to evaluate kidney function. The FDA is also asking doctors to warn patients not to take a double-dose if they miss a dose, because the extra high dose of Ampyra could increase the risk of seizure.
The FDA also recently sent a warning letter to the manufacturers of Ampyra regarding misleading statements in the promotional material for the drug. Although Ampyra is only approved to increase walking speed, as measured by a 25-foot walking test, video promotions for the drug showed patients snowboarding, horseback riding, and claiming they could “walk across Home Depot” without the use of a cane. The FDA was concerned that this “misleadingly suggests that treatment with Ampyra can have a positive impact on the disability caused by MS.” The FDA was also concerned that the promotional materials failed to prominently present risk information.