An experimental drug seems to help some people with multiple sclerosis to walk better, which could improve their quality of life, researchers said.

In this week's issue of the medical journal the Lancet, neurologist Dr. Andrew Goodman of the University of Rochester Medical Center and his colleagues reported the results of their trial comparing Acorda Therapeutics' drug fampridine with a placebo.

'As a clinician, I can say that improvement in walking speed could have important psychological value.'— Dr. Andrew Goodman

A progressive decline in mobility is a common feature of MS, and there are few pharmaceutical options to complement physiotherapy.

"The data suggest that, for a sub-set of MS patients, nervous system function is partially restored while taking the drug," Goodman said in a statement.

Goodman has served as a consultant to the company.

"As a clinician, I can say that improvement in walking speed could have important psychological value; it may give individuals the potential to regain some of the independence that they may have lost in their daily lives," he added.

The study looked at 301 adults in Canada and the U.S. with MS for 14 weeks.

About 35 per cent of subjects who previously had trouble walking increased their walking speed after taking fampridine, compared with eight per cent in those randomly assigned to take a placebo.

Those who showed improvements on the drug walked about 25 per cent faster over a distance of 7.5 metres than before they took the medication, compared with an improvement of five per cent in the placebo group.

They also reported having stronger legs and greater ease when doing activities such as standing and going up and down stairs.

In the study, 11 patients, or nearly five per cent, in the fampridine-treated group discontinued the study due to side effects. Of these, two — a focal seizure in a patient with sepsis and an episode of severe anxiety — were considered to be possibly related to treatment.

The study used a new, slow-release form of the drug. If approved by regulators, patients would only need to take it twice a day instead of three or four times, said Stewart Wong, a spokesman for the MS Society of Canada.

Hard to judge risks, benefits

In a journal commentary accompanying the study, Alan Thompson from University College London and Chris Polman from the VU Medical Centre in Amsterdam, welcomed the findings.

"However, although the data presented in today’s study show a clinically relevant improvement in function induced by fampridine, it is not easy to extrapolate these findings to daily practice," the pair wrote.

A better understanding of the clinical application of fampridine would allow doctors to weigh its benefits and risks.

More study is needed to determine who exactly it will help, Wong agreed.

The researchers did not distinguish between people who had different types of MS, which could make a difference when it comes to prescribing the drug to patients, he noted.

This formulation of the drug has not been approved by the U.S. Food and Drug Administration or Health Canada.

In multiple sclerosis, the immune system attacks the function of nerve fibres in the brain and spinal cord, interfering with the communication between the brain and the rest of the body.

It's thought that fampridine improves the transmission of signals in the central nervous system of some MS patients. It may do so by blocking potassium ion channels that regulate normal electrical activity, laboratory experiments suggest.

Hawthorne, New York-based Acorda Therapeutics funded the study. Some of the study's authors reported ties to the company. The commentators reported receiving fees from pharmaceutical companies that make other MS drugs.

MS is the most common disabling neurological condition affecting young adults and 2.5 million people worldwide. Canada is known to have one of the highest rates of MS in the world, with an estimated 55,000 to 75,000 people affected by the disease.