NEW YORK — Sexual innuendo is being muted in TV ads for Pfizer Inc.'s erection pill Viagra as drugmakers react to added U.S. scrutiny of promotional campaigns for medicines.

Instead of middle-aged bikers singing "Viva Viagra," as seen in a 2007 commercial, the latest Viagra ad shows a gray-haired man meeting with a doctor. After Pfizer's quit-smoking treatment Chantix was tied to suicides in 2008, the drugmaker added more than a minute of safety warnings into advertising that earlier had just 14 seconds.

Pfizer isn't alone in bringing a more serious tone to its ads. Bristol-Myers Squibb Co. now devotes half of a 60-second Plavix spot to side effects, twice the time in a 2005 ad for the blood thinner. The changes, tied to tighter enforcement of U.S. regulatory guidelines, are "increasingly noticeable" industrywide, said Maura Musciacco, an analyst with Datamonitor Plc. While the changes benefit consumers, they may hurt business, she said.

"Ads are becoming more subtle, and being subjected to much more scrutiny," said Musciacco, whose research company is based in London. "There has been a major change in the last few years. If we continue down this route, it may become counterproductive to advertise to consumers.

"The ads become less memorable and catchy and, at the end of the day, there may be a disincentive" for consumers to try a new product, she said.

RULES EASED IN '97

Advertisements for prescription medicine have flooded the air waves since 1997 when the U.S. Food and Drug Administration decided to allow drugmakers to shorten the time devoted to risks in their commercials, as long as they directed consumers to another source for more detailed information.

Over the past five years, the agency has increased the number of people monitoring ads by 50 percent to 60 in an effort to keep up, according to Thomas Abrams, director of the Division of Drug Marketing, Advertising and Communications.

In 2008, drug advertising was put under the spotlight by Congressmen John Dingell and Bart Stupak, two Democrats from Michigan who questioned whether drug advertising properly presented product benefits and risks. When Margaret Hamburg was confirmed FDA commissioner in May, she said the agency would more aggressively enforce existing guidelines.

As a result, the agency issued 41 warning letters to drugmakers, or almost double the number in 2008, according to the agency's database. The agency can assess fines, require that a company stop running an ad, force a correction, or even seize the product, according to the FDA.

"Our standards haven't changed, but we are trying to do a better job at reaching the industry," according to Abrams, who said that his staff reviewed more than 70,000 pieces of promotional material in 2009. "We are trying to reach companies so they can do the right thing."

One result of added enforcement may be fewer ads, said John Busbice, a principal in commercial effectiveness at IMS Health Inc., a market research company.

Pharmaceutical industry spending on consumer ads fell 4.7 percent to $3.25 billion in the first nine months of 2009, compared with the same period a year earlier, and 7.3 percent from 2007, according to The Nielsen Co.

While the recession has been partly to blame, the decline may also be driven by the increased scrutiny, Busbice said. "The FDA has now developed a reputation of being an active governing body," he said.

Jim Sage, Pfizer's vice president for U.S. primary care marketing, said Pfizer didn't change its strategy because of increased regulatory oversight. The new Chantix ads are designed to communicate the updated warnings to the drug's prescribing information by the FDA and encourage patients to talk to their doctors about quitting smoking, he said.

Pfizer submits all new ads to the FDA before airing them to get feedback from the agency, he said. The company has changed the tone of its commercials — for instance, more often using testimonials from real patients — because it believes the tactic will resonate more with consumers, Sage said.

Stupak and other lawmakers criticized Pfizer for using the inventor of an artificial heart, Robert Jarvik, to promote its cholesterol drug Lipitor because he isn't licensed to practice medicine and the ad didn't disclose he was paid for his endorsement.

Ads that began airing in September 2008 for Lipitor, the world's top-selling drug with $12 billion in yearly sales, show real patients talking about having a heart attack.

SEEKING CLARITY

In May, the FDA released draft guidelines designed to clarify what is appropriate in ads. They address issues such as raising music volume or using distracting images while the safety issues are being discussed.

Ruth Day, director of the Medical Cognition Laboratory at Duke University in Durham, N.C., said concerns about the ability of consumers to focus on safety warnings in commercials are legitimate. The use of quick-moving objects, flashes of light or changes in volume can distract viewers from a voiceover that lists safety warnings, said Day, who studies drug ads and how people use medical information.

As an example, Day cited a 2005 commercial for allergy drug Nasonex, made by Schering-Plough Corp., which featured an animated talking bee.

Viewers in a focus group couldn't remember any of the product's five side effects, Day said. The flapping from the bee's wings during the risk section may have distracted them, she said. In ads running now, the bee hovers during the warnings section and its wings are less visible.

Day calls the changes in drug ads "very good signs. Treating something serious in a serious way is getting more play in direct-to-consumer advertising than before," she said. "Instead of just having something cute or appealing happening when it comes time for the risks section, there is more of a serious air to a lot of the ads."