Weight-Loss Drugs -- Big Pharma's Elusive El Dorado

(MoneyWatch)  Half a dozen drug companies are simultaneously pursuing anti-obesity pills. The WSJ summarizes these efforts, but doesn't mention that Pfizer also has an anti-obesity drug in late-stage development that was expected to see daylight in 2009. But the estimated launch date for the drug, currently known only as CP-945598, has been pushed back to 2011.

With America's obesity problem getting worse by the day, there's plenty of money to be made fighting fat with new drugs. So what's the problem?

Drug companies have been down this route many times before, and always failed to find success. A safe and effective weight-loss pill is like Big Pharma's El Dorado -- a lost city of gold that no one can find.

GlaxoSmithKline, for instance, is currently marketing the weight-loss drug Alli -- but since its launch, it's sold only about $169 million, according to IRI, which tracks drugstores. At the same time, GSK has spent $141 million advertising the product -- and that doesn't count all the back-office and sales staff costs. Alli may not even have broken even yet.

One problem: Even Steven Burton, the exec in charge of marketing the drug, suffered from the diarrhea that often occurs while taking Alli. Such stories are pretty common -- GSK says roughly half of people taking the drug experience what it delicately refers to as "treatment effects."

GSK isn't alone in seeing minimal returns from diet drugs. Before it was called Alli, Roche sold the drug as a prescription brand called Xenical, and its sales stank. A year or so ago, Sanofi Aventis attempted to launch another diet pill, Acomplia, but the FDA turned it down because of side-effect worries. And, of course, Wyeth had to pull its fen-phen combination off the market more than a decade ago because of reports of heart damage.

Drugs generally attack a single biological mechanism, but our appetite and digestive system rely on a multitude of such processes -- all of them overlapping in such a way that one frequently steps in when another is disabled. Derek Lowe of In the Pipeline described the problem to me this way in an email:

Evolutionary pressures have been too strong - our metabolisms try to make absolutely sure that we have plenty of reserves against the lean times, because over most of the history of our species, it's been nothing but lean times....

So many of the weight loss drug attempts have been in the area of appetite suppression -- stop the problem before it develops. But you run into those multiple pathways there, too -- any animals whose feeding behaviors can be easily shut down are long dead. We're the descendants of the opposite population: the ones that scrambled for food no matter what.

Which raises some interesting questions about what, exactly, all these companies think they have got in the obesity pipelines.

Image via Flickr user colros, CC 2.0