February 8, 2010 / 10:36 PM / 8 years ago

Alzheimer's drug Dimebon helps Huntington's: study

WASHINGTON (Reuters) - Dimebon, a pill being developed for Alzheimer's disease, helped people with Huntington's disease improve their thinking, learning and memory skills, U.S. researchers said on Monday.

Dimebon, made by Medivation Inc. under the generic name latrepirdine, appears to be safe for Huntington's patients and has minimal side effects, the researchers reported in the journal Archives of Neurology.

Dr. Karl Kieburtz of the University of Rochester in New York said his team chose to study Dimebon because it appeared to have an impact both on cognition and aging.

"In diseases like Huntington's disease where there is degeneration of the brain, one thing we look for is compounds that might favorably influence that and sometimes those compounds come out of things that can slow natural aging," Kieburtz said in a telephone interview.

He said the independent study, involving 91 patients, was sponsored by Medivation. A new follow-up trial with 350 patients is being conducted to see whether the initial findings can be confirmed, Kieburtz said.

San Francisco-based Medivation has partnered with Pfizer Inc. to develop and commercialize latrepirdine for the treatment of Alzheimer's. The drug was first sold in Russia as an antihistamine.

Medivation chief executive David Hung said on Monday the company plans relatively soon to begin trials of altered forms of Dimebon, called analogues, that may have potential against an array of disorders, including Parkinson's disease, stroke and heart failure.

There is no cure for Huntington's disease, a highly disabling disorder in which brain cells are damaged. People who inherit the genetic mutation that causes Huntington's have a 100 percent chance of developing the fatal disease.

One drug, tetrabenazine, sold under the brand name Xenazine, can help manage some of Huntington's symptoms but does not prevent the physical and cognitive decline. Danish pharmaceuticals group Lundbeck owns the rights to Xenazine, which the company says has a sales potential of $250 million in the United States alone.

Kieburtz and colleagues studied people with mild to moderate Huntington's disease at 16 sites in the United States and one in Britain from July 2007 to July 2008.

Over 90 days, 46 of the volunteers were given 20 milligrams of latrepirdine three times a day. The other 45 patients took a placebo.

The researchers said Dimebon appears to stabilize and improve the functioning of cells damaged by the disease. It may act specifically on the mitochondria, powerhouses inside the cells that have their own unique DNA.

Side effects from the drug included headaches, falls and dizziness.

The patients who took Dimebon showed improvement in average scores on tests measuring cognitive function. The average scores of people in the placebo group remained steady, the report said.

"Huntington's disease is usually thought of as kind of a movement disorder, but the thinking and behavior problems are as, if not, more important than the motor problems of that disease," Kieburtz said.

(Additional reporting by Ransdell Pierson)

Editing by Maggie Fox and Cynthia Osterman

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