After more than five years of study, the Federal Trade Commission yesterday voted unanimously to abandon a proposal to regulate nonprescription drug advertising.

The rule the controversial consumer agency had under review would have barred drug companies from making any claims for products not authenticated by the federal Food and Drug Administration.

Critics say false claims are often made for over-the-counter drugs, and that these drugs are sometimes dangerous to health.

FTC Chairman Michael Pertschuk said the commission would continue to move "aggressively on a case-by-case basis" against advertising problems in the $4 billion nonprescription industry.

But the vote yesterday, the first major FTC action since the Reagan administration took office, was plainly a retreat by the beleaguered agency, which in recent years has been a favorite symbol and target for antiregulations, in Congress and out.

By attacking misleading advertising now on an individual rather than broad basis, the commission could be tied up for years in regulatory proceedings on each case, FTC staff officials said.

Pertschuk said the drug vote had nothing to do with politics. He said it was based on the judgment of the head of the FTC's Bureau of Consumer Protection, Albert Kramer. "This is not an action taken in reaction to the election," he added.

In part, the regulation was dropped, commission officials said, because the Food and Drug Administration failed to issue a final series of studies on these drugs. Pertschuk said only one of 60 monographs has been released.

"The commission is certainly going to take account of FDA findings as to the acceptability of claims in evaluating whether these claims are deceptive or not," Pertschuk said in an interview. "This decision is part of what the commission has been doing for the past four years -- taking a hard look at the evidence and the record in these trade regulation rules."

But Bruce Terris, an attorney who argued for the rule in representing the consumer affairs committee of Americans for Democratic Action, attacked the commission action. "At best it will be very ineffective," Terris said. "At worst, it will be nothing.

"The fact is that Congress has gutted the FTC and the pressure groups have gotten what they wanted. I think they [the FTC] were afraid to send this up to Congress.

"This rule represents a mandate that Congress provided for in 1962 -- tough regulation of over-the-counter drugs," Terris said. "They have not done what the Food and Drug Administration wanted. This is a terrible disappointment."

In 1975, the FDA asked the FTC to draft advertising rules for the industry. The rule has gone through several revisions. But in essence it would have required the industry to stick by requirements determined by the FDA in its over-the-counter drug review.

Specifically, the FTC asked the commission staff to prepare a closing notice for the proceeding and to draft a policy statement on the commission's enforcement plans. But commission member Robert Pitofsky said he was not inclined to support such a statement.

A spokesman for the key industry opponent of the FTC proposal, the Proprietary Association, which represents roughly 90 percent of the industry, lauded the commission action.

"The comments of the commission were quite gratifying to the association when they indicated their disinclination to promulgate a trade regulation rule in this proceeding," said Robert Altman, a lawyer with Clifford & Warnke, representing the trade group.

"This view is not only in accordance with common sense, but also with the record evidence in this lengthy proceeding. The commission did not uncover any evidence that the over-the-counter drug industry advertising practices were deceptive."

The trade group had complained the rule would have provided serious marketing difficulties for companies by forcing them to advertise using formal drug names that would have had little meaning for individual consumers.

Further, the industry complained the rule would have put over-the-counter drug makers at a disadvantage in competing with the producers of similar products that are not legally categorized as over the counter.

Yesterday, an FTC law judge barred Sterling Drug Inc., manufacturer of Bayer aspirin, Bayer children's aspirin, Cope and Vanquish, from making unsubstantiated claims about the contents and effectiveness of the products. Commission officials said the commission would move toward that type of enforcement rather than the sweeping industry rules, even though the case is seven years old.