FDA Revises Seizure Warning for MS Drug
The multiple sclerosis drug dalfampridine (Ampyra) can cause seizures in patients who are starting the medicine at normal doses, the FDA warned Monday.
Postmarketing adverse event reporting indicated that most seizures happened in patients with no history of seizures and occurred within days or weeks of starting the drug at its recommended dosage.
When dalfampridine was approved in 2010 to improve walking ability in MS, the FDA had noted the risk of seizures in patients who go over the approved 10 mg twice daily dosage and those with moderate to severe kidney disease.
The safety alert issued by the agency pointed out that the drug is excreted renally, so kidney impairment may lead to higher blood levels that raise seizure risk.
Patients' creatinine clearance should be measured before starting dalfampridine and at least annually while on the drug, even when serum creatinine appears normal, the FDA recommended.
Renal impairment is common after age 50 regardless of normal serum creatinine levels, the agency explained.
The drug is contraindicated in patients with a history of seizures or moderate to severe renal impairment with a creatinine clearance under 50 mL/min; the risk of seizures should be carefully weighed in those with mild renal impairment.
A seizure while taking dalfampridine is cause for permanent discontinuation of the drug.
Patients should be warned not to double up on doses if they miss one, the safety alert suggested.
The drug label is being updated to clarify these recommendations.
Dalfampridine is manufactured by Elan of Dublin, Ireland, and distributed by Acorda Therapeutics of Hawthorne, N.Y.
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Medical News: FDA Revises Seizure Warning for MS Drug - in Neurology, Multiple Sclerosis from MedPage Today
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