By Kathleen Doheny
WebMD Health News
Reviewed by Arefa Cassoobhoy, MD, MPH
Sept. 11, 2014 -- The FDA's approval on Wednesday of a new prescription weight-loss pill offers yet another option for the more than one-third of American adults who are obese. Called Contrave, the new drug is the third prescription weight-loss drug to be approved by the FDA since 2012. It's also approved for those not obese but overweight with risk factors such as high blood pressure, high cholesterol, or diabetes.
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Contrave combines two drugs already on the market: bupropion (Wellbutrin), an antidepressant, and naltrexone, an anti-addiction drug. Because it contains bupropion, the new drug will have a boxed warning to alert doctors and patients to the increased risk of suicidal thoughts that are linked with antidepressants.
The FDA approval came after the agency looked at new information it requested from the drug's maker in 2011 to be sure the drug was safe for the heart. Even so, the approval came with a requirement to do another study about the drug's effect on the heart.
Here's what else to know about the new drug.
How does Contrave work?
''It takes away hunger and the cravings for food," says John Foreyt, PhD, professor of medicine and director of the Behavioral Medicine Research Center at Baylor College of Medicine, Houston. He was a researcher on a clinical trial studying Contrave. He does not have financial ties to Orexigen, the drug's maker, or to Takeda Pharmaceuticals, which plans to market the new drug.
How the combination works for weight loss is not entirely understood, even by experts. The bupropion helps lessen appetite, says William Troy Donahoo, MD, an endocrinologist and weight loss specialist at Kaiser Permanente, Denver. The naltrexone, he says, probably works by blocking certain receptors in the brain and curbing cravings.
Who is eligible to take it?
The drug, a daily pill, is approved for use in adults with a body mass index or BMI of 30 (obese), or a BMI of 27 (overweight) with conditions that raise heart and stroke risks, such as high blood pressure, cholesterol, or type 2 diabetes.
A 5-foot-9-inch person who weighs 183 pounds has a BMI of 27. At 203 pounds, his or her BMI is 30.
Is the new drug meant to be used in combination with diet and exercise?
Absolutely, doctors agree. "If you try to use it in isolation, that patient is not going to have success," says Bipan Chand, MD. He's the director of the Loyola University Medical Center's Center for Metabolic Surgery and Bariatric Care.
The drug will help with controlling how much someone eats, Foreyt agrees, ''but we still have to watch what we eat and exercise regularly."
How much weight do people on this drug lose?
The amount varies, but on average, people lose 5% to 10% of their starting weight, according to clinical trials and experts.
In one 56-week study looking at Contrave combined with health habit changes, those on the drug lost more than 9% of their starting weight, while those on placebo lost just 5%.
So a 200-pound person losing 10% would end up at 180 pounds, perhaps moving from the obese to the overweight range, or the overweight to the healthy weight range.
In clinical trials that studied more than 4,500 people, the drug helped people keep off weight for up to a year, the length of the studies, according to Orexigen. On average, those who took Contrave for 6 months and combined it with a weight-management program lost 25 pounds, the company says in a statement. Those who were on placebo and the weight-management program averaged a 17-pound loss.
According to the FDA, people without diabetes who were in one of the clinical trials and took Contrave had an average weight loss, at the 1-year mark, of 4.1% over those who took the placebo pill.
In another study of those with type 2 diabetes, those on the drug lost 2% more than those on placebo.
In approving Contrave, the FDA says that those using it at the maintenance dose ''should be evaluated after 12 weeks to determine if the treatment is working." If the weight loss at that point is not at least 5% of starting weight, the drug should be stopped, according to the FDA, as it is not likely to work adequately and long-term for the patient.
If the drug is working, the label has limit on how long it can be taken.
The results seen in studies of the drug aren't always the same once the drug is on the market, Donahoo says. Once on the market, he says, the medicine may give better results than in clinical trials.
Part of the reason, he says, may be that doctors familiar with their patients can pick the weight loss drug they think may be most likely to work for a specific patient.
What are the side effects of the new drug?
In the clinical trials of Contrave, nausea was most common, reported by 34% of people, Foreyt says. Other complaints were headache, constipation, dizziness, vomiting, insomnia, dry mouth, and diarrhea, the FDA says.
The FDA rejected the request for approval of Contrave in 2011, requesting more information about the safety of the drug for the heart. In response, Orexigen launched the Contrave Light Study, including nearly 9,000 patients, to rule out excess heart and stroke risks in those taking the drug.
The interim results of the study, announced in late 2013, met the FDA goals, according to the company.
The FDA approval includes requirements for post-marketing research, including a heart outcomes trial to look at any heart and stroke risks. The company must also look at the potential for interactions between Contrave and other drugs, evaluate the best dose for patients with liver or kidney problems, look at the safety of the drug in children, and do other research.
How does Contrave compare to the other two recently approved weight-loss drugs?
No head-to-head comparison has been made of all three drugs -- Contrave, Belviq and Qsymia -- but experts can talk in general about how the drugs are alike and different.
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"There is no way to predict who will respond and will not" to the various drugs, Chand says. "It is trial and error."
What will Contrave cost?
Company spokespeople declined to estimate. But other experts expect it to be priced competitively with the other two prescription weight-loss drugs.
Both cost about $6 or $7 a day, or about $180 to $210 a month.
Insurance coverage for Qsymia and Belviq varies by plan.
Takeda, which will distribute Contrave, expects the drug to be available in the fall, says Denise Powell, a spokeswoman for Orexigen.
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