An experimental obesity drug, taken along with formal counseling on lifestyle changes, may spur greater weight loss than counseling alone, a new study finds.
The study of nearly 800 obese adults examined the effects of a drug called Contrave — which combines the antidepressant bupropion (Wellbutrin) and naltrexone, a medication used to treat alcohol and drug addiction.
The trial is one of four studies that the drug's developer, Orexigen Therapeutics, has sponsored in a bid to win approval from the U.S. Food and Drug Administration (FDA).
The other trials have so far shown that Contrave generally outperforms placebo pills in spurring weight loss; in one, for instance, study participants on the drug lost an average of 6 percent of their initial weight over one year, compared with just over 1 percent among placebo users.
The current findings support the previous results, and suggest that combining the medication with counseling on diet and lifestyle would provide further benefits, the researchers report in the journal Obesity.
They found that over one year, participants in the drug-plus-counseling group lost 9 percent of their initial weight, on average — versus an average of 5 percent among those who received behavioral counseling plus a placebo.
Orexigen recently filed for FDA approval of Contrave and has said that it expects the agency to give a ruling early next year.
The drug is one of three experimental weight-loss medications currently under FDA scrutiny. Later this week, an advisory panel to the agency is set to review Qnexa, a weight-loss drug developed by Vivus Inc. The drug combines phentermine, an appetite suppressant, with topiramate, an epilepsy medication that also happens to help control appetite. In documents made public on Tuesday, FDA staff said Onexa appears to help people shed pounds, but concerns remain about its safety.
The third candidate drug — lorcaserin, developed by Arena Pharmaceuticals Inc. — acts on certain receptors in a portion of the brain that regulates appetite and metabolism.
For its part, Contrave is believed to act on brain pathways involved in food craving.
These latest findings are based on 793 obese men and women who were randomly assigned to take either Contrave or a placebo for one year in addition to 28 sessions of group counseling on diet, exercise and behavioral tactics for encouraging weight loss — like eating more slowly and avoiding temptations.
Researchers led by Dr. Thomas A. Wadden, of the University of Pennsylvania in Philadelphia, found that after 56 weeks, the Contrave group shed more pounds overall. Just over 41 percent lost 10 percent or more of their starting weight, versus 20 percent of the placebo group; 29 percent lost at least 15 percent of their initial weight, compared with 11 percent of placebo users.
It remains to be seen what role, if any, Contrave or its would-be competitors might have in battling obesity, which now affects about one-third of U.S. adults.
Weight-loss drugs have had a troubled history, starting in 1997 when the medication known as "fen-phen" was withdrawn from the market after being linked to fatal heart-valve problems.
One component of that medication, fenfluramine, was taken off the market; the other, phentermine (now a component of Qnexa) is generally considered safe at low doses.
There are currently two weight-loss medications FDA-approved for longer-term use: sibutramine (Meridia) and orlistat (Xenical), the latter also being available in a lower-dose, over-the-counter version called Alli.
Those medications have had their problems as well. Meridia carries warnings about high blood pressure and a risk of heart attack and stroke in patients with heart problems, and is no longer sold in Europe. Xenical can cause serious liver problems, uncontrolled bowel movements and gas.
Among the side effects so far seen with Contrave are nausea, constipation, dizziness, abdominal pain and ringing in the ears. In the current study, 34 percent of Contrave users reported nausea, while one-quarter reported constipation — compared with 10 percent and 14 percent, respectively, in the placebo group.
The side effects were reported mainly during the first month of treatment, according to Wadden's team.
Besides the issue of side effects, experts generally caution people to temper their expectations regarding the effectiveness of any weight-loss drug. They stress that none is considered a "magic pill" that will work without the help of diet changes and regular exercise.
One of the FDA criteria for judging a weight-loss medication effective is that its average weight loss beat a placebo by 5 percentage points, which is a relatively modest benefit.
Still, research indicates that even moderate weight loss — 5 to 10 percent of a person's starting weight — can have health benefits for someone who is obese.
In the current study, Contrave users saw, along with their greater weight loss, a larger reduction in triglycerides (a type of blood fat) and insulin levels, and a greater gain in "good" HDL cholesterol levels.