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Contrave: New weight-loss hope?

July 22, 2009 |  2:04 pm

The quest for a weight-loss drug that a) works and b) doesn't have nasty side effects is proving tricky, but new hopes rear up from time to time

Here's the latest medicine in the spotlight: Contrave, by Orexigen Therapeutics. This week, the company announced that it had completed Phase III trial data involving several thousand patients.

In one of the trials, 48% of the patients lost more than 5% of their body weight after 56 weeks, compared with 16.4% of those taking a placebo. In another trial, the numbers were 56.3% compared with 17.1% for controls.

The amount of weight loss, on average, was 6.1% and 6.4% in the two trials, compared with 1.3% and 1.2%.

A third trial, on obese people with Type 2 diabetes, showed similar weight losses. Side effects were few, primarily nausea, headache and constipation, though there were two cases of gall bladder inflammation and two of seizures.

The data build on an earlier trial of about 700 people with similar effects.

Now the company is seeking FDA approval.

So what is this drug? It's a combo of two things:

--Naltrexone, used to lower cravings in opioid addicts and alcoholics. It acts by blocking opioid receptors in the brain. 

--Bupropion, the same drug that's in the antidepressant Wellbutrin and the anti-smoking aid Zyban.

Let's not get excited too soon. First off, a weight loss of 6% in someone who's obese is not miraculous -- though it may be all that we can ever expect from a drug, so stubbornly do our bodies resist the sensation of net calorie loss.

And though both these drugs are well-established, and the company reported no adverse psychological events in the Contrave trial, it's worth noting that black box warnings were recently slapped on Zybanto alert consumers that taking the drug might cause hostility, depression and other mood changes, and such warnings have been noted for Wellbutrin as well.   

Just last year, two anti-obesity drugs bit the dust, both quite different in action than Contrave. The drugs, in this case, were designed to do the opposite of what THC, the main active ingredient of marijuana, does to the appetite.

Yes, people lost weight on them, presumably via a kind of "anti-munchies" effect. But as you can read here, and here, Acomplia and another drug, taranabant, also had unwelcome psychiatric effects.

--Rosie Mestel


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