CHICAGO — Two years ago, scientists had high hopes for new pills that would help people quit smoking, lose weight and maybe kick other tough addictions like alcohol and cocaine.
The pills worked in a novel way, by blocking pleasure centers in the brain that provide the feel-good response from smoking or eating. Now it seems the drugs may block pleasure too well, possibly raising the risk of depression and suicide.
Margaret Bastian of suburban Rochester, N.Y., was among patients who reported problems with Chantix, a highly touted quit-smoking pill from Pfizer Inc. that has been linked to dozens of reports of suicides and hundreds of suicidal behaviors.
"I started to get severely depressed and just going down into that hole … the one you can't crawl out of," said Bastian, whose doctor took her off Chantix after she swallowed too many sleeping pills and other medicines one night.
Side effects also plague two other drugs:
• Rimonabant, an obesity pill sold as Acomplia in Europe, was tied to higher rates of depression and a suicide in a study last month. The maker, Sanofi-Aventis SA, still hopes to win its approval in the United States.
• Taranabant, a similar pill in late-stage testing, led to higher rates of depression and other side effects in a study last month. Its maker, Merck & Co., stopped testing it at middle and high doses.
The makers of the new drugs insist they are safe, although perhaps not for everyone, such as people with a history of depression. Having to restrict the drugs' use would be a big setback because it would deprive the very people who need help the most, since addictions and depression often go hand-in-hand, doctors say.
A bigger fear is that the whole approach may be in trouble. Researchers say blocking pleasure, especially the way the obesity drugs do, might take the fun out of many things, not just the harmful substances and behaviors these drugs target.
It may be possible to improve the drugs so they act more precisely. Chantix targets a different pathway — nicotine pleasure switches — and in a different way than the obesity drugs, which aim at the same pathway that gives pot smokers the munchies. That is one reason many doctors are optimistic that any risks about Chantix will prove manageable.
But doctors are no longer talking about so-called "super pills" for a host of addictions.
"It certainly diminishes my enthusiasm" to see these side effects, said Mark Egli, co-leader of medicine development at the National Institute on Alcohol Abuse and Alcoholism.
The buzz started four years ago, when studies showed rimonabant helped people shed weight and keep it off longer than previous pills had. It also was being tested for smoking cessation.
But in a new study last month, 43 percent of people taking rimonabant developed psychiatric issues versus 28 percent of those on dummy pills.