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Wellbutrin, one of the two drugs in Contrave, lacks the weight gain associated with other antidepressants (hopefully -- if it's supposed to be a diet drug) but carries a risk of seizures. And before you suggest its manufacturer raid the competition's Topamax, Orexigen is way ahead of you and already developed a related diet drug with an antiseizure agent built in.
The third drug, called lorcaserin, is also antidepressant-like -- ironically, it's similar to the mood improving ingredient in Fen Phen that was withdrawn -- and is also the only drug that is truly new. According to an article in the July 15 issue of the New England Journal of Medicine, almost half of patients on lorcaserin for a year lost five percent or more of their body weight and 70 percent maintained the weight loss in the second year (while still taking lorcaserin.) The FDA worried that lorcaserin would cause heart problems since it's is so similar to the withdrawn "fen" but it didn't in trials, says the manufacturer, Arena. Lorcaserin goes before an FDA advisory committee in September.
Clearly, lorcaserin and Contrave are safer than the superdrug Qnexa -- but they also cause half the weight loss! Why must a diet drug risk your health to make you lose weight?
"We've found (over and over) that human feeding behavior is protected by multiple, overlapping redundant pathways," says chemist Derek Lowe on his blog, In The Pipeline. "We are the descendants of a long line of creatures that have made eating and reproducing their absolute priorities in life, and neither of those behaviors are going to be altered lightly. The animals that can be convinced to voluntarily eat so little that they actually lose weight, just through modifying a single biochemical pathway, are all dead. Our ancestors were the other guys."
That's why even though patient Erin Aycock told the FDA advisory committee that Qnexa was like "instant willpower" and she "had the ability for the first time in my life to say 'I don't even care if I eat that cookie,'" she gained the weight right back when she went off the drug.
And others gain the weight back while still on drugs. "Extreme weight loss!! I looked emaciated and everyone thought I was on drugs! My Dad thought I had cancer that's how skinny I became, " writes a Topamax user on askapatient. "The weight loss died down though after about two years or so. Maybe more a year and half. Now I am as big as a house."
No, until scientists find a way to trump the "feeding behavior" of our ancestral heritage with its "multiple, overlapping redundant pathways," new diet drugs will probably not be the solution for weight loss. And "bad food, small portions" will continue to be the problem.
An earlier version of this report appeared on Alternet.org
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