WASHINGTON -- A drug currently approved to treat depression and help people quit smoking has shown promise as a potential weight-loss tool in a small pilot study, according to researchers at Duke University Medical Center. Results of their first eight weeks of research, prepared for presentation at the American Psychiatric Association meeting in Washington, showed that women who took buproprion SR, combined with a 1,600-calorie diet, lost four times more weight than women on a placebo, according to Duke psychiatrist Dr. Kishore Gadde, lead investigator of the study.
"Since the withdrawal of fenfluramine and dexfenfluramine, there has been a great need for effective medications," Gadde said. "More than 55 percent of Americans are considered overweight or obese, and obesity carries with it a tremendous risk of high blood pressure, coronary artery disease, diabetes and a variety of cancers. So it is vital that we identify new and better ways of helping people lose weight and thereby reduce their medical risks."
Gadde became interested in studying bupropion SR while consulting as a psychiatrist at the Duke University Diet and Fitness Center. When he placed patients on the drug to treat their mild depression, they lost significantly greater amounts of weight during that particular stay compared with previous visits to the center.
Gadde then approached Glaxo-Wellcome, which markets the drug, with a proposal to test bupropion SR=s weight-loss properties in non-depressed women weighing an average of 222 pounds. He chose a 1,600-calorie diet because it is just 500 calories below what an average woman would eat and thus is considered safe and well-tolerated.
At the end of eight weeks, the 18 women who completed the study and took the drug lost 6.21 percent of their body weight, compared with a 1.56 percent weight loss in the 13 women who took a placebo. Women using the drug received a maximum of 200 mg twice daily.
Subjects who responded to the drug during the first eight weeks appear to be losing additional weight as the treatment is continued past the six-month mark, said Gadde, although researchers have not completed analysis of these data yet. "Here we have a well-tolerated drug that has shown significant clinical benefits in reducing weight," Gadde said. "While we have to approach the results cautiously because the long-term results are not completed, we are very excited about the potential this drug has for treating obesity."
A newer-generation anti-depressant, bupropion SR is in a class by itself and has no appreciable effect on the brain chemical serotonin, as do the majority of newer anti-depressants. Bupropion SR works by increasing available amounts of norepinephrine and dopamine, two other brain chemicals implicated in the reward and pleasure pathways.
Gadde says its unique mechanism of action may account for why patients remark that bupropion does not suppress their appetite, but rather helps them feel satisfied more easily. "A lot of patients have said that, while on the drug, they can eat a small piece of pie and feel satisfied, although not necessarily full. So it appears they feel rewarded much quicker than they normally do without the drug." The only side effect commonly reported in this study was dry mouth. Burpopion SR is not approved by the FDA for weight loss and should not be used by patients with seizure disorders, anorexia or bulimia, Gadde said.
The study will continue for another 18 months. Data also are being collected on bone density and lean muscle mass. Preliminary results should be available later this summer.