July 26, 2012
FDA is warning patients and healthcare providers about the risk of seizures in multiple sclerosis patients taking dalfampridine (Ampyra®). Post-marketing adverse event reports suggest seizures commonly occur within the first week of starting therapy and in patients with no history of seizures. Patients with kidney impairment may be at an increased risk of seizures due to the potential for higher dalfampridine serum concentrations. FDA is updating the Ampyra® product label to include monitoring of kidney function prior to initiation of therapy and annually.
Dalfampridine (Ampyra®) is a medication labeled to improve walking in patients with multiple sclerosis and is known to cause seizures. Recent FDA evaluation of adverse event reports found the majority of seizures occur within days to weeks after initiation of dalfampridine at the recommended dose. Most patients experiencing a seizure were at least 50 years of age or older and potentially at risk for some degree of kidney impairment, which is common in older patients. Dalfampridine is cleared through the kidneys and may result in higher blood concentrations in patients with reduced kidney function. For those with mild kidney impairment (creatinine clearance 51-80 mL/min), the potential benefits of dalfampridine must be compared against the risk of seizures. Dalfampridine is contraindicated in patients with moderate to severe kidney impairment (creatinine clearance less than or equal to 50 mL/min) and in those with a history of seizures.
Assess creatinine clearance in all patients before starting dalfampridine and monitor patients at least annually while on the medication. Do not exceed dalfampridine doses of 10 mg twice daily. Discontinue dalfampridine permanently in patients who experience a seizure. Educate dalfampridine patients who have a seizure to stop taking the medication and to contact their doctor immediately. Remind patients to tell their doctor if they have kidney problems and to not double the dose of dalfampridine if they miss a dose.
Additional information is available at the following links:
- MedWatch Alert:
- Drug Safety Communication:
July 26, 2012; University of Utah, Drug Information Service. Copyright 2012, Drug Information Service, University of Utah, Salt Lake City, UT.