Study Design
This multi-center, double-blind, randomized 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 randomized 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% - 100% 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.
*Slim-Fastâ is a registered trademark of Slim-Fast Foods Company.
Results
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%) than those receiving Bupropion SR 300mg/day (7.2%) or those receiving placebo (5%).
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% and 7.5%, 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% and 6.4%, 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.”
Wellbutrin SR® (bupropion HCl) Sustained-Release Tablets and Zyban® (bupropion HCl) Sustained-Release Tablets contain the same active ingredient; thus, they should not be used in combination with each other or any other medications that contain bupropion. Wellbutrin SR and Zyban are contraindicated in patients who have or have had a seizure disorder, patients with a current or prior diagnosis of bulimia or anorexia nervosa, or who are currently taking or have recently taken (within 14 days) a monoamine oxidase (MAO) inhibitor. The use of Bupropion SR is associated with a dose-dependent risk of seizure; therefore, higher than recommended doses should not be prescribed. When treating patients with severe hepatic cirrhosis, extreme caution should be exercised and a reduced dosage and/or frequency is required to avoid accumulation. There have been reports of hypertension, in some cases severe, in patients receiving bupropion alone and in combination with nicotine replacement therapy. GlaxoSmithKline provided funding for this research.
GlaxoSmithKline, one of the world’s leading research-based pharmaceutical and healthcare companies, is committed to improving the quality of human life by enabling people to do more, feel better and live longer.
*Editor’s note: Dr. Anderson will make an oral presentation of data from the study, “Bupropion SR Significantly Enhances Weight Loss When Used With a Moderate-Intensity Lifestyle Intervention: A 48-week Study” (abstract #100531), on Monday, February 25 at 1:45 p.m. (PST) at the San Diego Convention Center in San Diego, CA. The 1st Annual Nutrition Week Scientific and Clinical Forum and Exposition is jointly hosted by the American College of Nutrition, American Society for Clinical Nutrition, American Society for Parenteral and Enteral Nutrition and North American Association for the Study of Obesity.
Contacts:
Holly Russell
919-483-2839
Mary Margaret Colliver
859-257-3303 (University of Kentucky)