The Food and Drug Administration has approved a new diet pill, Contrave, one of only three obesity medications to pass muster with the agency in the last decade.
Contrave is a combination of two already approved drugs: naltrexone, which is used to treat alcohol and drug addiction, and bupropion, which is commonly sold under the brand Wellbutrin and is used to treat depression and help people quit smoking.
The drug’s California-based maker, Orexigen Therapeutics, said in a conference call Thursday that “the exact neurochemical effects of Contrave leading to weight loss are not fully understood.” It said the pill is believed to affect both the hypothalamus — a part of the brain that regulates appetite — and the mesolimbic pathway, a circuit of brain cells involving the neurotransmitter dopamine that deals with behavior rewards and habit formation.
“Obesity continues to be a major public health concern,” Jean-Marc Guettier, director of the division of metabolism and endocrinology products at the FDA’s Center for Drug Evaluation and Research, said in a news release about the drug. “When used as directed in combination with a healthy lifestyle that includes a reduced-calorie diet and exercise, Contrave provides another treatment option for chronic weight management for people who are obese or are overweight and have at least one weight-related health condition.”
Contrave is approved for adults who are obese, which the Centers for Disease Control and Prevention defines as having a body mass index (BMI) of 30 or more, and for people who are overweight, with a BMI of 27 to 30, and have at least one weight-related condition, such as Type 2 diabetes or high blood pressure.
The CDC says more than one-third of American adults — 78.6 million people — are obese, which puts them at greater risk for heart disease, stroke, Type 2 diabetes and some types of cancer.
In clinical trials Contrave helped patients lose 2.0 percent to 4.1 percent more of their total body weight in one year than people did who took a placebo; 36 to 42 percent of people lost at least 5 percent of their body weight in a year, depending on whether they had Type 2 diabetes. (Those who didn’t lost more weight, on average.)
The FDA said Contrave can cause seizures, raised blood pressure and elevated heart rate, and the agency is requiring Orexigen to launch trials to gauge the drug’s cardiovascular risk.
And because the pill contains bupropion, it will contain a warning on the box about increased risk of suicidal thoughts and behaviors that are associated with antidepressant drugs.
Diet pills have had a controversial reputation after the much-hyped FDA approval — and then withdrawal in 1997 — of weight-loss medication fenfluramine and dexfenfluramine, a combination of drugs usually called fen-phen that was found to cause heart valve damage.
More than a decade later, two other diet pills, Belviq and Qsymia, won FDA approval in 2012. The average weight loss on Belviq is in range similar to Contrave’s; Qsymia patients lost more weight in clinical trials, from 6.7 to 8.9 percent of their body weight, on average.
Despite the prevalence of obesity in the U.S., experts have said cost has been a major obstacle to more widespread use of FDA-approved weight-loss pills because insurance companies typically do not cover them, forcing people to pay out of pocket.
They also stress that pills are not a magic fix for the problem. “All patients have to treat their obesity with diet and exercise,” said Dr. Adam Tsai, chair of the public affairs committee at the Obesity Society, an organization based in Silver Spring, Maryland, that is dedicated to studying obesity. “Medications and surgeries are tools to help patients with their diet and exercise.”
He called the weight loss exhibited in Contrave patients “modest,” pointing out that it equates to losing approximately 10 pounds in someone with a starting weight of 200.
“I don’t think it’s going to be a blockbuster,” Tsai said, “but I do think it’s going to give us an additional tool in our toolbox.”