Study: Obese Patients Lose Weight With Wellbutrin/Naltrexone Combo Pill
Editor's note: On Dec. 7, 2010, an FDA advisory committee recommended approval of Contrave. The FDA is expected to make its final decision in early 2011.
June 8, 2009 -- A new weight loss drug looks good in late-stage clinical trials.
The drug is Contrave, from Orexigen Therapeutics Inc. It's a combination of two existing drugs: The antidepressant Wellbutrin and the addiction drug naltrexone.
Contrave doesn't work in the belly. It works in the hypothalamus, the brain's central thermostat that controls appetite, temperature, and how the body burns energy.
It's already known that people lose weight soon after starting Wellbutrin treatment. But this effect soon wears off, and people regain weight. That's where the naltrexone comes in, says endocrinologist Dennis D. Kim, MD, MBA, Orexigen's senior vice president for medical affairs.
"Naltrexone comes in and lifts the brake on the Wellbutrin effect," Kim tells WebMD. "So you have a synergistic effect to signal the hypothalamus to reduce food intake. Weight decrease is maintained over time."
That sounds good in theory. But does it work?
The drug was tested in a clinical trial that enrolled nearly 700 obese people -- 90% of them women, with an average weight of 223 pounds. All study participants enrolled in an intensive weight loss program that included counseling, diet, and exercise. Two-thirds of the study participants also took Contrave.
Just under 60% of the participants stayed in the program for 56 weeks.
The intensive weight loss program worked well. After 56 weeks, they had an overall weight loss of just over 5% of their body weight -- 11 to 16 pounds. Moreover, 11% of participants who finished the study lost more than 15% of their body weight.
But those who took Contrave did even better. After 56 weeks, they lost 9.3% of their body weight -- 20 to 25 pounds. And more than 29% of them lost more than 15% of their body weight.
Nausea, usually mild or moderate, was a frequent side effect of Contrave treatment. More patients on Contrave also reported mild-to-moderate headaches and constipation. All these side effects tended to occur early in the study.