The Food and Drug Administration is proposing to allow pharmaceutical companies to contradict official safety warnings in sales presentations to customers.

Though an FDA warning can scare off buyers, the new proposal would allow drugmakers to present customers with information that undermines official warnings as long as it comes from a peer-reviewed journal article.

The proposal is supported by the manufacturers, who argue the policy would allow them to give doctors and hospitals the benefits of the latest research.

But the proposal is drawing criticism from public-health advocates, who argue that because individual studies can differ widely in their results, a drug company could easily mislead customers - and possibly endanger patients - by presenting only a selection of new research.

The proposal "seriously undermines FDA authority," Sidney Wolfe, founder of Public Citizen's Health Research Group, wrote the agency. "Its main supporters are drug companies and their associations, all of which would benefit from being allowed and encouraged to sell more drugs by making them seem safer than FDA has judged them to be."

Under the proposal, the FDA would not "object to the distribution of new risk information that rebuts, mitigates, or refines risk information in the approved labeling." Studies must be "well-designed" and "at least as informative as the data sources" the FDA used in generating the official warning.

For example, a drugmaker could present evidence that the severity or frequency of a side effect is less than that suggested by the FDA-approved label. Or it could question whether the drug causes the side effect at all.

Exactly what drugmakers can tell customers has been the subject of regulation and sometimes - when the side effect has led to heart attacks, cancer, or suicide - billion-dollar penalties. But the industry has pushed back in recent years, arguing that under First Amendment, the government cannot curtail their right to disseminate information.

The proposal seems bound to increase drug sales because it is explicitly geared toward undermining the FDA warnings, rather than enhancing them, critics said. The proposal allows the dissemination of information that "rebuts or mitigates" the risk identified by the FDA, or information that "refines" the risk as long as it "does not indicate greater seriousness of the risk."

In a letter to the FDA, the pharmaceutical industry's chief lobbying group, PhRMA, said that while the agency has an "important role in evaluating the safety and efficacy of new medicines . . . we also must recognize the critical need for health-care professionals to receive the most current, accurate and comprehensive scientific information."

"The Constitution's protection of an open and robust exchange of ideas . . . limits FDA's ability to regulate scientific communication," according to the letter signed by PhRMA vice president Jeffrey K. Francer. "PhRMA respectfully submits that FDA should give additional consideration to these First Amendment limitations in issuing final guidance."