FRIDAY, Jan. 22 (HealthDay News) -- Dalfampridine (Ampyra) extended-release tablets have been approved by the U.S. Food and Drug Administration to help adults with multiple sclerosis (MS) who have trouble walking.

In clinical testing, people who took Ampyra had faster walking speeds that those who took a placebo, the agency said in a news release.

MS is a chronic, often disabling disease affecting the brain, spinal cord and optic nerves. Some 400,000 people in the United States and 2.5 million globally have been diagnosed with the disease, the FDA said.

The drug, if given at doses higher than the recommended 10 milligrams twice daily, can cause seizures, the agency warned. The most common reported side effects include urinary tract infection, insomnia, dizziness, headache, nausea, weakness, back pain, nasal or throat swelling, irregularity, indigestion and burning or itchy skin.

People with moderate-to-severe kidney disease shouldn't take Ampyra, the FDA said.

The drug is marketed in the United States by Hawthorne, N.Y.-based Acorda Therapeutics.

More information

The FDA has more about this approval.