Federal regulators plan to study whether relaxing, upbeat images featured in TV drug ads distract consumers from warnings about the drugs' risks.

The announcement, posted Tuesday to the Food and Drug Administration's Web site, comes a week after a study published in the New England Journal of Medicine suggested the agency's drug-ad enforcement has steadily declined.

The FDA says it plans to study how 2,000 people react to television drug ads to determine whether they have an overwhelmingly positive impression of products despite audio warnings about potential side effects.

In a statement released Tuesday, the Washington-based Pharmaceutical Research and Manufacturers of America said TV ads are an important way for patients to learn about diseases and treatments.

Drug companies are legally required to present a balanced picture of a drug's benefits and risks in promotions. But critics charge that the images of smiling and relaxed couples and families featured in ads overshadow audio warnings about possible complications.

One ad for Eli Lilly & Co.'s impotence drug Cialis features a middle-aged couple walking hand-in-hand past a restaurant while smooth jazz plays in the background. Toward the ad's end, a male voice lists common side effects, including headache, back pain and muscle aches.

"If advertisers were really interested in getting information about drug risks out, they'd show pictures of those problems, but you almost never see that," said Dr. Sidney Wolfe of the advocacy group Public Citizen, which frequently criticizes drug industry marketing.

According to the authors of the NEJM article, the FDA sent 21 citations to drug companies last year for problems with consumer-directed ads, compared with 142 in 1997.

During the same period, drug industry spending on such advertising soared 330 percent, to $29.9 billion in 2005 from $11.4 billion in 1996.

The U.S. is one of two industrialized countries that permit TV drug ads — the other is New Zealand.

The FDA's Tuesday announcement says a study is needed on whether some ads "simply distract consumers from carefully considering and encoding risk information."

Besides looking at how images used in ads affect consumers, the FDA will also study how text on the screen can focus or divert attention from audio warnings. FDA says text directing viewers to company Web sites or magazine advertisements can distract viewers from more important audio about side effects. On the other hand, FDA said the repetition of language about risks in text format could help reinforce warnings.

In response to increased scrutiny, the Pharmaceutical Research and Manufacturers of America recently issued voluntary guidelines for members on promoting drugs to patients. Members include Pfizer Inc., Merck & Co. Inc., Wyeth and most other major pharmaceutical companies.

The guidelines recommend companies submit TV ads to the FDA for review before broadcast. Drug companies agreed to start paying the agency $80,000 per ad to offset the cost of hiring more drug ad reviewers.

Last month, however, House lawmakers rejected the proposal, recommending that federal money finance the regulatory reviews. The legislators said having drug companies pay salaries of FDA ad reviewers could create potential conflicts of interest.

House lawmakers are slated to meet with their Senate counterparts in September to work out differences between companion bills aimed at increasing the FDA's enforcement powers.