WASHINGTON (January 22, 2010)--Federal health regulators Friday approved an Acorda Therapeutics drug that’s designed to improve walking in patients with multiple sclerosis, an often-disabling disease that affects the nervous system.

The U.S. Food and Drug Administration says Ampyra is the first drug approved to help multiple sclerosis patients walk.

The agency says 400,000 people in the U.S. have the disease, which affects the brain and nervous system, causing loss of balance, muscle spasms and other movement problems.

Acorda, based in Hawthorne, N.Y., conducted two trials tracking patients' ability to complete a walking exercise, and both studies showed significant improvement in patients' walking speed.