Sept. 25 (Bloomberg) -- Shares of Acorda Therapeutics Inc. rose almost fourfold after the company said its experimental Fampridine drug helped people with multiple sclerosis walk faster.

Patients who took Fampridine-SR moved 25 percent faster on average during a timed 25-foot walk, while patients getting a placebo improved 4.7 percent, Hawthorne, New York-based Acorda said today. Patients on the drug also had increased leg strength, even those who didn't show improvement in walking.

Chief Executive Officer Ron Cohen said Acorda believes it met all three criteria the U.S. Food and Drug Administration set to establish that the drug works and plans to meet with the agency as soon as possible. About 80 percent of the 400,000 Americans with multiple sclerosis have some trouble walking, according to Acorda, which first sold shares publicly in February.

``It's a drug to help improve the symptoms of MS, and there's not any other product labeled to help with walking disability,'' said Philip Nadeau, an analyst with Cowen & Co. in New York, in a telephone interview. ``It will be complementary to everything that's out there right now.''

Shares of Acorda rose $6.28, or 283 percent, to $8.50 at 4 p.m. New York time in Nasdaq Stock Market composite trading. About 23.3 million shares traded, almost 800 times the three- month daily average. The stock's previous highest closing price was $6.72 on Feb. 10, one day after its initial public offering of shares.

Nadeau said he couldn't remember the last time he had seen a company's shares rise so much in one day.

Potential Sales

The 301-person study of Fampridine-SR, a sustained-release formula of the drug, was in the last of three phases of human testing generally required for FDA approval. Patients in the trial continued to take their usual MS medications, including interferons such as Biogen Idec Inc.'s Avonex. The company will discuss with the agency whether further trials will be needed, Cohen said in a conference call with investors and analysts.

Nadeau said the drug may reach the market in 2009 and generate $75 million of sales in 2011. He rates the shares ``outperform'' and doesn't own any.

Acorda, established in 1995, has one product on the market, the Zanaflex drug to help manage stiffness and muscle spasms in patients with multiple sclerosis or spinal-cord injuries, according to the company's Web site.

Fampridine has been shown to improve communication between damaged nerves. Existing MS drugs either relieve symptoms such as pain or slow the disease's progression.

``The best you can do is slow down the deterioration over time,'' Cohen said in a telephone interview.

Side Effects

Two patients in the Fampridine-SR study stopped taking the drug, one after a seizure and another because of anxiety. The increased risk of seizures appears to be related to higher doses, Cohen said. Ten milligrams of the drug were given twice daily to 229 patients in the study, while 72 received a placebo, he said.

Patients who took the drug also were more likely to report dizziness, insomnia, fatigue, nausea, back pain and balance disorder.

Acorda hasn't decided what the drug would cost. The company wants to position Fampridine-SR in the market between symptom- relief therapies, which cost patients as much as $4,500 a year, and treatments that slow progression at a cost of $10,000 to $20,000 annually, Chief Operating Officer Mary Fisher said during the conference call.

To contact the reporters on this story: Catherine Larkin in Washington at clarkin4@bloomberg.net; Angela Zimm in Boston azimm@bloomberg.net.

Last Updated: September 25, 2006 17:52 EDT