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Bupropion SR Plus Lifestyle Intervention Results in Significant Weight Loss

SAN DIEGO, CA -- February 26, 2002 -- In a multi-center, placebo-controlled study, the sustained-release formulation of bupropion hydrochloride (Bupropion SR) in combination with a lifestyle intervention program that included an energy-restricted diet and exercise, resulted in significant weight loss in obese patients up to 24 weeks.

Furthermore, a 24-week extension of the study showed that the average percentage of weight loss was maintained in patients who continued on this regimen for the total 48 weeks. The data were reported today at the first annual Nutrition Week conference, co-hosted by several organizations including the American College of Nutrition.

Bupropion SR is marketed as Wellbutrin SR® (bupropion HCl) Sustained-Release Tablets for the treatment of depression, and Zyban® (bupropion HCl) Sustained-Release Tablets, as an aid to smoking cessation treatment. Bupropion SR has not been approved by FDA for weight loss and has not been studied extensively in obese patients

This multi-center, double-blind, randomised study compared the changes in weight in patients receiving Bupropion SR at 300 mg/day and 400 mg/day to placebo during the first 24 weeks. Investigators then examined subsequent effects on body weight following an additional 24 weeks. In the subsequent 24 weeks, patients who initially received Bupropion SR continued with their treatment regimens, and subjects in the placebo group were randomised to active treatment of 300 mg/day or 400 mg/day of Bupropion SR.

More than 300 non-depressed, clinically obese men and women (as defined by a Body Mass Index of 30-44 kg/m2 or about 30 percent - 100 percent above their ideal body weight) participated in the investigation; 227 patients completed the initial 24 weeks and 192 completed the full 48 weeks. Exclusion criteria included history of Bupropion SR use in past 12 months, predisposition to seizures, history of anorexia or bulimia, significant cardiovascular disease, current depression, uncontrolled hypertension, diabetes, untreated hypothyroidism, history of significant hepatic, renal, gastrointestinal, or psychiatric disease, addiction to nicotine or recent cessation of smoking, use of weight loss agents in the past three months, or history of alcohol or substance abuse.

All patients maintained a moderate exercise regimen in addition to a reduced-calorie diet (600 fewer calories per day than normally would be required to maintain the subject's current weight) facilitated by the use of a twice-daily meal replacement (Slim-Fastâ) during the first 24 weeks, then once daily for the second 24 weeks. In addition, all subjects recorded food intake and physical activity in a daily diary and attended 12 visits to a clinic where lifestyle goals were reinforced.

During the initial 24-week period, individuals completing the study and receiving Bupropion SR lost statistically significantly more weight than those in the placebo group (placebo + lifestyle intervention program). Individuals assigned to Bupropion SR 400mg/day lost a larger percentage of initial body weight (10.1 percent) than those receiving Bupropion SR 300mg/day (7.2 percent) or those receiving placebo (5 percent).

Investigators then initiated a 24-week follow-on study to determine if weight loss could be maintained over a 48-week period. At the end of the second 24-week period, the average percentage weight lost from initial body weight for patients completing the study and receiving Bupropion SR 400mg/ day or 300mg/day was 8.6 percent and 7.5 percent, respectively.

Completers who received placebo for the first 24 weeks and were switched to Bupropion SR 400mg/day or 300mg/day during the 24-week extension lost an average of 7.2 percent and 6.4 percent, respectively, of their initial body weight by week 48.

Patient withdrawals did not differ significantly between treatment groups. In addition, there were no significant differences in the occurrence of adverse events across treatment arms. The most common adverse events experienced in this study at the highest dose that were greater than placebo were headache, dry mouth and diarrhea. Further study is necessary to determine conclusively the effect of Bupropion SR on weight loss in obese patients, particularly with respect to maintenance of weight loss, which in this study was not measured in a placebo-controlled setting for the full 48 weeks. The safety risks associated with the use of Bupropion SR for weight loss have not been thoroughly evaluated.

"We are encouraged by these preliminary results in non-depressed obese patients," said James W. Anderson, MD, professor of medicine and clinical nutrition at the University of Kentucky College of Medicine and lead investigator of this study. "Even modest weight loss, if maintained, could produce significant health benefits."

SOURCE: GlaxoSmithKline

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