Contrave Weighs in Lighter Than Expected

Orexigen Therapeutics Inc on Thursday reported the results of their first 56-week phase III study on contrave, a combination of the antidepressant bupropion and the opioid-antagonist naltrexone (both drugs have been on the market for other indications for over 20 years).

Although participants in this almost 800 patient study lost an average of 9.3% of their initial body weight on contrave vs. only 5.1% on placebo, the difference falls just short of the 5% placebo-corrected weight loss generally considered by the FDA as a threshold for approval.

Drop-out rates on contrave were 26% vs. 13% on placebo – the major side effects being nausea, hives, anxiety, headache, constipation and dizziness (nothing alarming or unexpected here).

Participants on contreve experienced significant improvement in quality of life and markers of cardiovascular risk as well as reductions in food cravings.

Despite falling just short of the FDA criteria in this study, the company still expects that the results of their remaining three phase III trials (expected to be completed later this year) will meet the mark.

It will certainly be interesting to see if there are certain subsets of patients who will respond better to this drug than to existing treatments.

As I have frequently said before, I do not expect any single drug to be effective in all obese patients. Given the mode of action of this drug, I would expect to see the greatest effect in individuals with emotional eating and food addictions.

Matching the right patient with the right medication will remain the single biggest challenge in the future development of anti-obesity medications.

Edmonton, Alberta