A TV ad campaign earlier this year told psoriasis sufferers they could get the unsightly skin disease “off their back” with regular injections of Amgen Inc.’s drug Enbrel.

Then the Thousand Oaks biotech giant was warned by the Food and Drug Administration that the spot significantly oversold Enbrel’s benefits and downplayed its risks, prompting Amgen to quickly pull the ad.

Now, the world’s largest biotech company is pledging to alter the way it conducts its direct-to-consumer campaigns, which like others by pharmaceutical companies, have come under attack for driving up drug costs.

Amgen is pledging to have any new campaigns reviewed by the FDA before they are aired. The pledge applies for both new drugs and older drugs that have been advertised for years. “The end result is getting the patient accurate, timely information,” said company spokeswoman Christine Cassiano.

Amgen’s change of policy stems from an initiative by the Pharmaceutical Research and Manufacturers of America, the industry’s largest lobbying and trade group, which is asking its members to follow a series of new advertising guidelines.

The initiative comes after a series of scandals involving heavily advertised drugs now found to have more serious side effects than previously announced, including the painkiller Vioxx, which was taken off the market after being associated with heart attacks and strokes.

While it covers all forms of advertising, television ads have attracted the most criticism. Senate Majority Leader Bill Frist, a physician, last month proposed a moratorium on the advertising.

The guidelines suggest that companies submit ads to the FDA before they’re aired, that claims be supported by “substantial evidence,” and that spots balance any benefits and drawbacks, among other changes.

The guidelines have been adopted by 25 of the 33 member companies of the trade group so far. Cassiano said that Amgen is committing to stricter changes because the guidelines do not specifically require ads to have FDA ‘pre-clearance” before they are aired.

Part of the reason might be that Amgen traditionally has not advertised to consumers as much as other drug companies. The company launched its first such ad only a few years ago for its second-generation infection fighter Neulasta.

Despite the seemingly far-reaching changes, industry critics remain skeptical of the guidelines, arguing they are voluntary and include enough wiggle room to still allow deceptive ads.

“The industry, left to its own devices, doesn’t regulate itself,” said Dr. Sidney Wolfe, director of Public Citizen’s Health Research Group. “Aside from lack in teeth, the guidelines are themselves more like the ads they attempt to regulate.”