Contrave, a drug combination of Wellbutrin (bupropion) and naltrexone, causes the most weight loss with doses of 400 mg of Wellbutrin (bupropion) plus 32 mg of immediate-release naltrexone according to a press release from Orexigen Therapeutics, the company developing this drug combination.

Contrave, a combination of Wellbutrin (bupropion) and naltrexone, at the optimum doses of 400 mg of Wellbutrin (bupropion) plus 32 mg of immediate-release naltrexone, caused an average weight loss of 10.7 percent after eleven months according to a press release from Orexigen Therapeutics, the company developing this drug combination.

Drop out rates for the first six months for those given Contrave, with various doses of Wellbutrin (bupropion) and naltrexone, were 7.9 percent for those given 32 mg of naltrexone plus 400 mg of Wellbutrin (bupropion) compared to 18 percent for those given 48 mg of naltrexone plus 400 mg of Wellbutrin (bupropion) according to a press release from Orexigen Therapeutics, the company developing this drug combination.

Nausea was the most common adverse effect of Contrave, the drug combination of 32 mg of naltrexone plus 400 mg of Wellbutrin (bupropion) according to a press release from Orexigen Therapeutics, the company developing this drug combination. Other side effects include headache, dizziness and insomnia. “There was no indication of meaningful adverse effects of Contrave therapy on vital signs including blood pressure and pulse, ECG intervals, laboratory evaluations or… depression,” the press release noted.

Among patients who completed the six month study, those given Contrave, a drug combination of Wellbutrin (bupropion) and naltrexone, lost an average of 6.8 percent of their body weight in six months compared to 3.8 percent for those given Wellbutrin (bupropion) alone, 2.2 percent for for those given naltrexone alone, and 1 percent for patients given a placebo according a paper by Frank Greenway and George Bray (2007). (The placebo group was discontinued after four months.)

Among patients who finished the study, those given Contrave, with higher than 300 mg doses of Wellbutrin (bupropion) and one of three different doses of naltrexone—I assume less than 50 mg used in the previous study in order to try and reduce nausea—lost an average of 7 percent to 7.6 percent after six months compared to 1.1 percent for those given a placebo. After nine months, the average weight loss for those still in the study was 8 percent to 9.3 percent.