Merck Obesity Drug Helps Shed Pounds, Increases Irritability

By Shannon Pettypiece

March 31 (Bloomberg) -- Merck & Co.'s experimental obesity pill taranabant helped some people lose three times more weight than diet and exercise and had side effects that include irritability and depressed mood, a study showed.

People taking taranabant for a year on average lost 9 pounds more than those on placebo, according to data presented today at the American College of Cardiology meeting in Chicago. Both groups followed the same diet and exercise program. Taranabant is in final testing and Merck plans to seek U.S. approval this year.

Merck's pill is similar to rimonabant developed by Sanofi- Aventis SA, which failed to win backing from a U.S. regulatory panel last year because of increased suicide risk, a side effect not seen at the lower doses of Merck's drug. The company said it stopped testing the higher dose and has extended studies of taranabant to monitor psychological side effects.

"Taranabant is structurally distinct, it does work on the same receptor, but taranabant is very selective," said John Amatruda, Merck's vice president of clinical research for diabetes and obesity. "I think the general medical community is becoming more and more aware that weight loss is really important in preventing chronic illness."

The Whitehouse Station, New Jersey-based company plans to report results of five other large-scale tests of taranabant this year. The studies look at the effect of lower dosages.

The drug could generate $500 million in sales by 2012, said Cowen & Co. analyst Steve Scala in a March 11 research report.

Body Weight

About 57 percent of patients in the study lost 5 percent of their body weight, compared with 27 percent of those who only dieted and exercised, the study showed. Those results suggest the treatment is approvable because it meets a U.S. Food and Drug Administration requirement for weight loss effectiveness, Merck said.

"The agency has displayed some flexibility at meeting this endpoint in the past, but we anticipate this would be dependant on a favorable safety profile," said Leerink Swann analyst Aileen Salares in a research report.

Both the Merck and Sanofi drugs block a receptor in the brain and digestive system that researchers believe also makes marijuana smokers hungry. By turning off the mechanism, scientists believe they can suppress appetite.

About 31 percent of Americans over age 20 have abnormally high body fat, according to the National Institute of Diabetes and Digestive and Kidney Diseases. About 33 percent are obese, according to the Centers for Disease Control and Prevention.

Lagging Market

Despite the number of obese Americans, the market for prescription weight loss products has lagged with $478 million in sales because of side effects from existing products, according to a March report by health research firm Decision Resources Inc. Effective and safe treatments could help the market grow to $2.7 billion by 2016, the report said.

GlaxoSmithKline Plc has sold about $300 million of its diet pill Alli in the U.S. since June, when the drug went on sale without a prescription.

Sanofi, France's biggest drugmaker, withdrew its application to sell rimonabant in June after an FDA panel of advisors recommended it not be approved following the suicides of three patients. The drug is sold outside the U.S. as Acomplia.

"The FDA's increasing concern regarding the long-term safety of drugs used to treat chronic conditions poses one of the most significant threats to companies developing anti- obesity drugs," the report by Decision Resources said.

Psychiatric Effects

Total reports of psychiatric side effects were 28.3 percent for people taking taranabant at the lowest dose of 2 milligrams, compared with 20.4 percent on placebo. Digestive problems including nausea and diarrhea also were more common, affecting 41.8 percent of taranabant users compared with 28.5 percent on placebo.

Pfizer Inc. is also developing a drug that targets the same receptor in the brain as Merck and Sanofi's. New York-based Pfizer's pill is about two years behind Merck's in testing, according to Cowen's Scala.
 

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