Approval brings company a big step closer to a $60 million milestone payment.

The U.S. Food and Drug Administration has approved Belviq, the first new obesity drug in 13 years and the first drug among several vying for the chance to address one of the nation's most pressing public health crises.

Belviq’s developer Arena Pharmaceuticals now stands to collect a $60 million milestone payment from its U.S. marketing and distribution partner, Eisai, once it delivers initial supplies of the drug for launch in 2013.

Compared to a placebo, Belviq helped obese patients using reduced calorie diets and exercise counseling lose an average 3 percent to 3.7 percent of their total body weight by activating a brain receptor that helps some eat less and feel full after eating smaller amounts of food.

The number of U.S. adults and children who are obese has remained relatively constant over recent years, according to two recent studies published in the Journal of the American Medical Association. In 2009 and 2010, about one in three adults and one in six children and teens were obese. The ratios showed no change from the 2007-2008 figures and, aside from a few specific demographics, demonstrated only a slight increase in the prevalence of obesity from turn of the century numbers.

“Obesity threatens the overall well being of patients and is a major public health concern,” says Janet Woodcock, director of the FDA’s Center for Drug Evaluation and Research. “The approval of this drug, used responsibly in combination with a healthy diet and lifestyle, provides a treatment option for Americans who are obese or are overweight and have at least one weight-related co-morbid condition.”

Belviq, a brand name for lorcaserin hydrochloride, was approved after a lengthy review for use in adults considered obese or overweight who have at least one weight-related condition such as high blood pressure, type 2 diabetes, or high cholesterol. The drug works by activating the serotonin 2C receptor in the brain.

The weight-loss drugs fenfluramine and dexfenfluramine, which activated the serotonin 2B receptor, were withdrawn from the market in 1997 after evidence emerged that they caused heart valve damage. The FDA says that Belviq does not appear to activate that receptor.

About 47 percent of patients without type 2 diabetes lost at least 5 percent of their body weight while using Belviq compared with about 23 percent of patients treated with placebo. In people with type 2 diabetes, about 38 percent of patients treated with Belviq and 16 percent treated with placebo lost at least 5 percent of their body weight. Trials also showed the drug to be associated with favorable changes in glycemic control in patients with type 2 diabetes.

To ensure federal health authorities remain on top of any unexpected side effects that crop up when Belviq enters broader use, Arena will be required to conduct six post-marketing studies, including a long-term cardiovascular outcomes trial to assess the effect of the drug on the risk for major adverse cardiac events such as heart attack and stroke. 

By MICHAEL FITZHUGH