Q & A: How Safe is the Weight-Loss Drug Contrave?

A weight-loss drug called Contrave may be approved by the Food and Drug Administration in the coming weeks if the agency follows the advice of one of its panels, which recently weighed in on the matter.

On Tuesday, the FDA panel voted 13 to 7 to recommend the drug for approval, according to news reports. The FDA often follows the recommendations of its panels, and is scheduled to make a final decision regarding Contrave by Jan. 31.

The vote comes shortly after the administration denied approval of two other weight loss drugs: lorcaserin manufactured by Arena Pharmaceuticals Inc. and Qnexa made by Vivus Inc. Last month, Abbott Laboratories withdrew its weight loss drug Meridia from the U.S. market after studies linked it to an increased risk of heart attack and stroke.

Experts have expressed concern over the new drug's potential side effects, which may pose hazards to the health of patients. For example, studies have linked the drug to seizures, said Dr. Pieter Cohen, an assistant professor of medicine at Harvard Medical School who researches the effects of dietary supplements.

And the fact that pharmaceutical companies appear to be simply "repackaging" old pills in the hopes of generating a new solution for those who are overweight is also cause for concern, Cohen said. Contrave is made up of two medications — one antidepressant and one that treats addictions — that individually had been shown to lead to slight weight loss as a side effect.

We spoke with Cohen about Contrave's safety, and whether such pills are really the way to go to tackle the obesity epidemic.

Q: Were you surprised the FDA panel recommended Contrave for approval this week?

A: Unfortunately, I can't say I was surprised. "Disappointed" would probably be a more accurate description.

Q: Why were you disappointed?

A: I think the panel recommendation advising to approve Contrave is a big step backward for people — patients waiting for an effective treatment for obesity, which we're certainly lacking.

Q: Are there questions about the drug's safety?

A: Even before thinking about the safety of the drug, it's interesting to take a look at whether or not it's going to be beneficial.

The problem with Contrave is that we're, first off, just talking about a very small amount of weight loss — just over 4 percent in clinical trials. So if you're 225 pounds, we're talking about losing less than 10 pounds if you took this for an entire year. If you stopped after a year of taking Contrave, you would very likely gain the weight right back.

So if you wanted to keep that 10 pounds off for a long period of time, you have to take the medicine for presumably the rest of your life. And we don’t have any safety data regarding its long-term health effects.

We [also] don’t know if losing this modest amount of weight by taking this pill will provide any health benefit.

Q: This drug is actually made of two different drugs. What might that mean for its side effects?

A: So the bupropion, which has been widely used to treat depression…is well known to cause seizures.

In the pharmaceutical [company] supported studies that are being used as evidence that this medication is effective, more patients who received the drug experienced seizures than patients who received placebo.

This is quite remarkable, because the manufacturer was careful to exclude anyone with a known seizure disorder.

So if you just imagine, when used more broadly, and when patients aren't carefully screened — or as carefully screened as they were in the clinical trials — that we're going to be seeing a lot more serious side effects, including seizures, if this pill were to be prescribed widely.

Q: Are there also concerns about side effects on the heart?

A: It's certainly concerning to see that the patients in the trials of Contrave had increases in blood pressure and increases in pulse.

This could be a marker that it could have more serious cardiac side effects down the road.

Specifically, bupropion, one of the two medications, has been reported to have caused death by heart attacks.

Whether or not that is a causal relationship, bupropion actually caused those heart attacks, or it was just a coincidence, is not known. We wouldn't have the data about that for years, until another much larger study is completed.

Q: But the panel also voted in favor of more studies to investigate whether the drug does confer heart risks.

A: Right, but where does that leave us? That leaves us in a situation where, if its approved by the FDA — and heavily marketed as we would expect by the pharmaceutical company — we're going to have thousands, maybe millions of people who use this before we know whether or not it actually is causing  more heart attacks [and] strokes.

Q: In your opinion, is it too soon to approve this drug?

A: I think spending much time even studying Contrave more is a waste of our resources. What the field of obesity needs are real innovative approaches to treating obesity. Thousands and thousands of people have already taken both of these medications that are combined in Contrave, and it causes very modest weight loss. This is not the game changer that we need. In the field of obesity, in terms of medical treatments to move forward, we're going to need completely innovative products to be developed.

Repackaging these drugs that are already available … based on their side effects is a terrible decision in my mind.

[If the drug were approved, the FDA would be] sending a signal that all you need to do is meet very modest standards and repackage an old medication…for approval.

The FDA should be sending the signal to pharmaceutical companies that, unless you're coming in with a truly innovative product, unless you are demonstrating that innovative product's safety, it won't be approved.

So I think this would be a huge step backward as pharmaceutical companies would then turn to other well known medications with very modest weight loss potential and try to repackage them.

This is the most unfortunate part of the story, if the FDA does decide to approve Contrave.

Pass it on: The FDA might approve the weight-loss drug Contrave, but it is not a good way to treat obesity, experts say.

Follow MyHealthNewsDaily staff writer Rachael Rettner on Twitter @Rachael_MHND.

Rachael Rettner

Rachael is a Live Science contributor, and was a former channel editor and senior writer for Live Science between 2010 and 2022. She has a master's degree in journalism from New York University's Science, Health and Environmental Reporting Program. She also holds a B.S. in molecular biology and an M.S. in biology from the University of California, San Diego. Her work has appeared in Scienceline, The Washington Post and Scientific American.