NEW YORK — Client confidentiality prevents Andrew Schirmer from revealing specifics, but it's easy to believe his claim that his job has been especially challenging lately.

Schirmer is trying to devise a new ad campaign for Viagra, Pfizer Inc.'s erectile-dysfunction drug, at a time when racy spots for impotency pills helped fuel the public's ire over drug commercials. There hasn't been a Viagra TV ad since November 2004, when regulators requested Pfizer halt the commercials because they violated several regulations, including making unsubstantiated claims.

"With all the sex in ads, this is the one place where we can't use sex," laments Schirmer, managing director of McCann HumanCare, an agency specializing in healthcare ads.

Facing a furor over its advertising practices and the potential of more government regulation, the pharmaceutical industry adopted voluntary guidelines in January to improve the accuracy and balance of ads so the severity of diseases and drugs' side effects aren't whitewashed.

The guidelines, announced last summer, have sparked changes: Spending on brand advertising is flat while disease awareness campaigns are flourishing. The look of the ads has become more straightforward; doctors bluntly describing products is becoming de rigueur.

The possibility of more government regulation looms. Late last year, the U.S. Food and Drug Administration held two days of public hearings on drug advertising and is now reviewing comments. The FDA said it is too early to say whether any new rules will be instituted, but some say it is likely.

"Whenever there is a public hearing, it is a sign that change is coming," said Gary Messplay, a lawyer who represents drug companies. While Messplay praised the guidelines he said they were "a little too little, a little too late."

Only 18 percent of consumers believe pharmaceutical ads can be trusted "most of the time," according to a study released last year by the Kaiser Family Foundation. That's down by almost half since 1997, when one-third of people surveyed said you could trust ads most of the time.

The withdrawal of Merck & Co. pain reliever Vioxx in September 2004 cast a harsh spotlight on direct-to-consumer ads. The heavily promoted drug was found to have potentially lethal side effects after long-term use.

Last year, U.S. Senate Majority Leader Bill Frist, R-Tenn., called for a two-year moratorium on advertising new drugs, saying commercials drive up healthcare costs. Thirty-five percent of American adults favor such a ban, according to a survey conducted last year by Harris Interactive for the Wall Street Journal Online.

Total spending on drug advertising rose 4.9 percent to $4.7 billion in 2005, according to TNS Media Intelligence. Spending on branded ads was essentially flat at $4.1 billion. Both categories had been up over 20 percent the previous two years.

The flat spending on brand advertising can be tied to the lack of ads for Vioxx and another drug in the same class, Pfizer's Celebrex, as well as drops in advertising for impotency drugs and some antidepressants, said Jon Swallen, director of research at TNS.

Meanwhile, spending on corporate and disease-awareness commercials — a fraction of drug advertising — rose 44.4 percent to $523 million. The industry guidelines called for more disease awareness ads, such as Pfizer's campaign on erectile dysfunction and Eli Lilly and Co.'s ads about depression.

Schirmer said the new commercials reflect an environment where companies are wary of airing campaigns that could violate industry guidelines or FDA regulations.

There has been "an explosion of white coats on television ads," commercials featuring doctors frankly discussing drugs' benefits and risks, Schirmer said. Drugs with such campaigns recently include Zetia, a cholesterol-lowering drug made by Merck and Schering-Plough Corp.; Toprol XL, a blood-pressure medicine by AstraZeneca PLC and Ortho Evra, a birth-control pill from Johnson & Johnson. Pfizer soon will launch a TV campaign for cholesterol-lowering agent Lipitor featuring a physician.

Ruth Day, a professor at Duke University who studies drug ads, said the parade of doctors more accurately reflects the seriousness of prescription drugs than some earlier "cute" ads.

But the trend troubles some ad agency executives who say if commercials look alike patients will tune out the messages.

"There is just a lot of safeness out there now," said Schirmer. "We can't get the hot shot creative types we could two years ago and that horrifies me."

Clients may be less willing to take creative risks, said Matt Giegerich, president and CEO of communications company CommonHealth. For example, CommonHealth created a campaign for AstraZeneca's cholesterol medicine Crestor, featuring a Dr. Seuss-like rhyme extolling the product that was criticized for trivializing a serious condition. Giegerich doubted the ad would be accepted today even though it was very effective, because no company wants its commercial to be a lightning rod for critics.

Companies are shifting money away from TV ads into other avenues such as public relations and the Internet because it is difficult to present a balanced portrait of a drug in a 30-second or 60-second spot, Giegerich said.

Pat Kelly, president of Pfizer U.S. Pharmaceuticals, said the company is not skittish about creative commercials, saying the new guidelines are "a perfect opportunity for (ad executives) to come up with new approaches."

Meanwhile, the quest for the Viagra ad continues. No new campaign is scheduled and Kelly concedes developing new ads isn't easy. "This medicine is associated with sex," he said. "Nothing associated with sex doesn't create criticism."