More Questions Over Depression Drugs

New research stokes more controversy over antidepressants.

People with mild to moderate cases of depression may get little benefit from common treatments like Paxil, University of Pennsylvania researchers concluded after reviewing six drug studies. While effective as treatments for people with severe cases, antidepressants had no more benefit than a placebo for people with less-serious conditions, according to the study published in the Journal of the American Medical Association.

The researchers looked at three studies involving patients taking the chemical ingredient in Paxil and three trials for imipramine, a drug developed in the 1950s, which has long been generic. Once dominated by brand-name drugs, generic competitors like Teva Pharamaceutical Industries Ltd. and Novartis AG's Sandoz unit account for much of the depression-drug sales.

In recent years, depression drugs began carrying warnings about the risk of suicide. U.S. officials have even suggested companies expand their warning labels. Yet, American doctors are prescribing plenty of them.

Damien Conover, an analyst at Morningstar Inc., says if suicide warnings don't scare off people, he doubts that doctors are going to stop prescribing depression drugs if patients want them. While the University of Pennsylvania study focused on the effectiveness of the drugs versus placebos, there's something to be said about the effect people think they're getting from the pills.

"The placebo effect in antidepressants is very, very high," Conover says.

As a class of drugs, antidepressants were the fifth-biggest selling in the U.S. with total revenue of $9.6 billion in 2008, according to IMS Health data. That dollar figure is down 14 percent from 2004 because of the introduction of generic versions, which are considerably less expensive than branded drugs. In 2006, patents on two big-selling antidepressants—Paxil and Pfizer Inc.'s Zoloft—expired, opening both those drugs to generic competitors.

Despite warnings that some of theses drugs can lead to suicide, prescriptions of antidepressants are rising, according to IMS. There were 164 million prescriptions for antidepressants in 2008, up 15 percent from 2004. The depression drugs were the third-most prescribed class of drugs behind cholesterol medicines and pain killers.

British drugmaker GlaxoSmithKline Plc and Indianapolis-based Eli Lilly & Co. are among the leading makers of brand-name depression drugs. Glaxo makes Paxil and Lilly makes Prozac, older, popular drugs that have generic competitors but were once blockbuster sellers. Lilly also makes Cymbalta, which loses its patent in 2013.

To get Food and Drug Administration approval, companies perform human studies to show that their treatments work. Through these studies, companies prove their drugs are effective in people with severe depression, but many patients who get prescriptions from their doctors may have only mild cases, the researchers say.

"Efforts should be made to clarify to clinicians and prospective patients that whereas (antidepressants) can have a substantial effect with more severe depressions, there is little evidence to suggest that they produce specific pharmacological benefit for the majority of patients with less severe acute depressions," the study authors wrote.