As blogged previously, there are a number of weight loss drugs currently under study. The latest study on a combination weight loss medication called Contrave shows good effect to induce weight loss, but with the potential for significant side effects that must be taken into careful consideration.

Contrave is a combination of two medications already on the market: bupropion, a smoking cessation agent and antidepressant, and naltrexone, which is used to treat alcohol or narcotic addictions. The study, published in a recent edition of The Lancet by Greenway and colleagues, compares the effect of this combination medication in two different doses compared to placebo. In this 56 week trial, participants taking the combination drug in higher dose lost 6.1% of their body weight, compared to 1.3% in the placebo group. This amount of weight loss rivals, or is superior to, weight loss seen with our currently available weight loss drugs, sibutramine and orlistat respectively.

As noted in an accompanying editorial in The Lancet by my colleague Dr. Arne Astrup, from the Department of Human Nutrition, University of Copenhagen, an upside of this proposed new weight loss combination drug is that both medications have been around since the mid 1980s, and as such, we are quite knowledgeable of the potential side effects of each individual drug. For example, it is known that both drugs can cause anxiety and a small increase in blood pressure. What is not known, however, is whether these particular side effects could be additive in nature. Though the current study did not find any increase in anxiety, they did find less blood pressure reduction at 1 year than would have been expected with the weight loss that was seen. Thus, it is exceptionally important that cardiovascular risk factors and outcomes are closely monitored as we gain more experience with this combination medication.

Overall, Contrave may represent an effective and generally well tolerated addition to our current sparse armamentarium of weight loss medications, if it is ultimately approved by regulatory agencies. However, as always, we must remain vigilant for the potential of unwanted side effects, and continually monitor and evaluate outcomes.

Dr Sue Pedersen © 2010

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