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Thursday, May 29, 2008

Addiction Drug for Obesity?

This week, Orexigen, a biopharmaceutical company in La Jolla, CA, announced that it won a patent covering its obesity drug Contrave.

Contrave actually consists of a sustained-release version of two older drugs: bupropion, which is currently used as an antidepressant and smoking cessation aid, and naltrexone, which is used for opioid addiction and alcoholism. Contrave is currently undergoing Phase III trials for obesity and the company hopes to file for FDA approval in late 2009.

Why is Contrave, a combination of two drugs that have been around for a while, novel?

Firstly, there is no doubt that depression is a common problem in treatment-seeking obese individuals, many of whom are "self-medicating" with food - i.e. eating highly palatable foods that increase serotonin levels in the brain to improve their mood (albeit temporarily). There is indeed evidence that buproprion may help some people lose weight.

Secondly, many patients with obesity will be the first to admit that for them eating is akin to an addiction - a statement that is not surprising given that opioid-mediated reward mechanisms may play an important role in the hedonic aspects of ingestive behaviour and that this behaviour may well involve exactly the same neurocircuitary that plays a role in other addictions.

So the idea of combining two drugs that address depression and addiction, respectively, is certainly one with merit and may well prove to be highly effective in obese patients in whom depression and hedonic eating are significantly contributing to hyperphagia.

I have not seen data from these trials and have no relationship with Orexigen. I do however, like the concept of this drug and can't wait to try it on some of my patients, who I can well imagine would benefit.

Obviously, we need to await the results of the Phase III program and certainly need to very carefully look at the side effect profile of the two drugs used in combination.

But I do think that this could indeed be a useful drug for some patients battling obesity - although it is unlikely to be the "magic bullet" for everyone.

Remember, obesity is a highly complex and heterogeneous disorder and there is absolutely no reason why any one treatment should work for all.

Edmonton, Alberta

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