For the first time in more than a decade, the FDA has approved a new drug to help people lose weight.

Today, Arena Pharmaceuticals' Belviq (lorcaserin hydrochloride) became the first prescription weight loss drug approved by federal regulators in 13 years.

The FDA approved Belviq as an addition to a reduced-calorie diet and exercise, for use in chronic weight control.

The approval is specifically for use in adults with a BMI above 30 (considered obese), and for adults with a BMI of 27 (considered overweight) or above if they also have at least one weight-related medical condition, such as high blood pressure, type 2 diabetes, or high cholesterol.

Belviq should not be used during pregnancy.

Today's move comes almost two years after the FDA refused to approve the drug, citing concerns about its safety and effectiveness.

But last May, an FDA advisory committee overwhelmingly endorsed making the drug available to people who are obese and those with health issues related to being overweight.

The drug's manufacturer will be required to conduct six post-marketing studies, including a long-term trial to look for heart attack and stroke risks, the FDA announced today.

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Weight Loss Drug Targets Hunger Center

Belviq works by targeting a key area of the brain that regulates appetite, known as the serotonin 2C receptor.

This is the same appetite-controlling hormone targeted by fenfluramine, the "fen" component of the notorious 1990s diet drug combo fen-phen. Fen-phen was linked to potentially life-threatening heart valve problems in as many as one in three users.

But Belviq is much more selective than fenfluramine and much safer, its manufacturer says, because it specifically targets serotonin receptors associated with hunger.

In a study published two years ago in the New England Journal of Medicine, about half of obese people who took the drug for a year lost at least 5% of their body weight, compared to 20% of dieters who took a placebo pill, while about 1 in 5 Belviq users lost 10% or more of their body weight, compared to 1 in 14 placebo users.

People who continued on the drug for two years were able to maintain their weight loss better than those who switched to placebo after one year.

Study participants were monitored closely for heart valve irregularities, and no difference was seen in the two groups.
One Dieter's Story

Lisa Sutter, who lives in suburban Washington D.C., credits Belviq with helping her lose 40 pounds.

Sutter took the drug for a year during the clinical trial, and she says it changed her relationship with food.

At the FDA hearing in May, Sutter told the panel that she gained weight after her children were born and found it impossible to lose it before enrolling in the trial.

"When I was on the drug I was able to stick to a 1,500- or 1,600-calorie-a-day diet without feeling hungry," she told WebMD. "And when I ate more than I planned to, I felt uncomfortably full, which is not something that I was used to."

Sutter was switched to the placebo arm of the study in her second year of enrollment and the weight started to creep back on.

She now weighs 30 pounds more than she did before enrolling in the trial and she says she plans to go back on the drug as soon as she can.

"I'm not saying this drug is the answer for everyone, but it worked well for me," she says.
Belviq Appears Safe, but Concerns Remain

But an FDA panel that met to consider the drug in 2010 had other concerns about the drug's safety, citing tumors that developed in lab animals.

At the FDA hearing in May, some panel members continued to express concerns that the drug may cause breast tumors or heart valve problems.

The panel voted 18 to 4 to recommend the drug's approval, citing the need for new obesity treatments.

"Obesity is one of the biggest health problems we face in this nation and, unfortunately the diet and lifestyle message is not working for many people," says diabetes specialist Abraham Thomas, MD, who chaired the May FDA advisory committee meeting.

Thomas, who is an endocrinologist at Henry Ford Hospital in Detroit, said during the May meeting that questions about heart valve safety in Belviq users had not been fully resolved.

But in an interview with WebMD, he called echocardiogram findings in Belviq users reassuring. These tests showed no evidence of an increase in heart valve issues.

"Ideally, we will have other drug options in the future for obesity instead of just a few so that if one drug doesn't work we can try another or a combination," he says.

Arena spokesman David Schull tells WebMD that Belviq is unique among the weight loss drugs the FDA is considering because it is a new drug discovered and developed by the company.

Qnexa, another weight loss drug awaiting FDA approval, is a combination of two already prescribed medications, the antiseizure drug topiramate and the appetite suppressant phentermine, the "phen" half of fen-phen.

Early this year, an FDA advisory committee overwhelmingly recommended Qnexa's approval as an obesity drug, and a final vote is scheduled for mid-July.

Along with the restriction on use during pregnancy, there are other side effects associated with Belviq.

It can cause serious side effects, according to the FDA, including serotonin syndrome, particularly when taken with certain medicines that increase serotonin levels or activate serotonin receptors. These include drugs commonly used to treat depression and migraine. Belviq may also cause disturbances in attention or memory.