Eisai Co.’s epilepsy drug Zonegran helped obese people lose weight, according to a study that shows the potential of another antiseizure medication to aid in weight reduction.

Obese people who took 400 milligrams of Zonegran a day for a year had a 3.3 kilograms (7.3 pounds) greater weight loss than those on a placebo, according to the study published today in Archives of Internal Medicine. The efficacy was similar to Roche Holding AG’s Xenical and Arena Pharmaceuticals Inc.’s Belviq. Side effects such as mood changes and memory problems occurred more frequently than with a placebo, the authors of the study at Duke University Medical Center in Durham, North Carolina, said.

“The drug’s benefit-to-risk ratio needs thoughtful and cautious assessment,” the researchers said in the study.

The U.S.-funded study is the first randomized, controlled trial to evaluate Tokyo-based Eisai’s Zonegran, also known as zomisamide, as a monotherapy weight-loss drug, the researchers said. Zonisamide is used in Orexigen Therapeutics Inc.’s experimental drug Empatic for obesity, combined with an antidepressant bupropion. Vivus Inc.’s Qnexa, which won U.S. approval in July, contains the antiseizure medication Topamax combined with the appetite suppressant phentermine.

Obesity has more than doubled since 1980 worldwide. More than 1.4 billion adults were overweight and, of these, about 500 million men and women were obese in 2008, said the World Health Organization. In the U.S., more than a third of adults are obese. Medical costs associated with obesity were estimated at $147 billion in 2008 in the world’s largest economy, according to the Center for Disease Control and Prevention.

‘Dire Need’

“For obese patients who do not achieve adequate benefit from lifestyle therapies, there is a dire need for additional nonsurgical therapeutic options,” the researchers wrote in the study.

The study of Eisai’s medicine involved 225 people whose body mass index was 37.6 on average and didn’t have diabetes. Individuals took a placebo, 200 milligrams or 400 milligrams of Zonegran in addition to receiving diet and lifestyle counseling by a dietician for a year. The daily dose of 200 milligrams wasn’t efficacious, the study said.

Obesity for adults is defined as having a body mass index greater than 30. The index represents weight in kilograms divided by height in meters squared. Overweight for adults is defined as having BMI of 25 to 30.

Eisai fell 20 yen, or 0.6 percent, to 3,395 yen. The stock has risen 6.6 percent this year, while the benchmark Topix Index has dropped 0.8 percent.

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