Sen. Gaylord Nelson (D.Wis.) charged yesterday that some large pharmaceutical manufacturers sell under their own high-priced brand names drugs quietly made for them by small generic firms.

He said the brand name companies claim to make the medicines in their own plants as part of a "publicity blitz" intended to persuade the public that their products are safer and more effective than generic drugs costing one-fifth to one-third as much.

Nelson declined to identify products engaging in the practice or to indicate the event but said specifices will be disclosed in three days of hearings to be held by his Senate Monopoly Subcommittee starting Nov. 14. He has not yet issued a witness list.

Under what the industry refers to as the "man-in-the-plant" technique, Nelson said, a major brand name company rents a small producers plant for a week or two and installs one of its own employees while usually use less expensive generic medicines are labelled with the large firm's own name.

The drug is the same drugs that the generic house has always made, Nelson said.

For 29 years, the large brand name drug firms have spent billions of dollars trying to convince the public that brand name drugs are somehow superior to the same products sold under their official (or generic) names," Nelson said.

"These claims are absolutely ridiculous," he said. "What is even more absurd is the widely trumpted claim by the large brand name manufacturers that only the reputation of the manufacturer can assure that drugs meet the standards of the law . . . Simply because a drug manufacturer's name is widely known is no assurance that its product is better."

Nelson said only the Food and Drug Administration, through its inspection and testing, can assure the public that drugs they take meet the requirements of the law."