The FDA announced Wednesday that the drug is approved for adults with a body mass index (BMI) of 30 or over - which indicates obesity - or with a BMI of 27 or greater (overweight) who have at least one weight-related health problem such as high blood pressure, Type 2 diabetes or high cholesterol. It is manufactured by Switzerland-based Arena Pharmaceuticals.
"Obesity threatens the overall well being of patients and is a major public health concern," Dr. Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said in a written statement. "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 comorbid condition."
There are currently two prescription drugs used to treat obesity including the appetite-suppressant phentermine, and orlistat (Xenical), which prevents dietary fat from being absorbed by the intestine. Orlistat is sold over-the-counter as Alli in a lower dose.
The FDA cited three studies of nearly 8,000 overweight and obese patients - with or without Type 2 diabetes - who were treated from 52 weeks to 104 weeks with the drug or a placebo, along with exercise and diet counseling. The studies found about 47 percent of patients without Type 2 diabetes lost at least 5 percent of their body weight compared with about 23 percent of patients treated with placebo. In people with Type 2 diabetes, about 38 percent of patients treated with Belviq lost at least 5 percent of their body weight, compared to 16 percent in patients treated with placebo.
The drug's label will recommend that people stop taking the pill if they don't lose 5 percent of their body weight after 12 weeks of treatment, as those patients are unlikely to achieve meaningful weight loss even with continuing treatment. The drug should also not be taken by pregnant women.
Side effects from Belviq include serotonin syndrome - a potentially life-threatening drug reaction that causes the body to produce too much serotonin and causes symptoms of agitation, diarrhea, heavy sweating, fever, muscle spasms, tremors or mental health changes. People taking antidepressants or migraine drugs that increase serotonin levels may be at an increased risk for this side effect. The drug may also cause "disturbances in attention or memory," the FDA said.
Belviq should be used with caution in people who have congestive heart failure, according to the FDA, but studies found no significant difference in heart valve problems between people taking Belviq and those taking a placebo. Studies of some earlier weight loss pills reported heart valve damage as a potential side effect.
Arena will be required to conduct six postmarketing studies, including a long-term cardiovascular outcomes trial to assess the effect of Belviq on the risk for major cardiac events such as heart attack and stroke, the FDA said.
In May, a panel of expert advisers to the FDA voted 18-4 with one abstention to recommend the agency approve the pill saying its benefits "outweigh the potential risks when used long term."
The pill was initially rejected by the FDA in 2010, which called any weight loss the drug produces in overweight people who don't have diabetes "marginal." FDA scientists also raised concerns about health issues such as tumors that developed in laboratory animals given the drug.
Earlier this year a rival drug, Vivus Inc.'s Qnexa, won endorsement from an FDA panel after previously being rejected due to safety concerns. The drug's approval is currently pending.