As the US Food and Drug Administration considers the use of radio frequency identification tags to help fight counterfeit prescription drugs, privacy advocates are cautiously watching to be sure consumer privacy isn't lost in the process.

Last year, the FDA called for the widespread use of RFID tags to help ensure that drugs sold to consumers are legitimate. Under the FDA proposal, RFID tags would be used on cartons and pallets of drugs throughout the pharmaceutical supply chain by 2007.

The problem, according to privacy advocates, is that the FDA is considering more than just tracking large shipping containers or crates of medicines with RFID tags; it could also use the tags to track individual medicine bottles or even individual tablets. That, privacy advocates said, would be invasive.

Dr. Scott Gottlieb, deputy commissioner of medical and scientific affairs at the FDA, said the agency has talked with pharmaceutical companies, retailers, scientists and others for the past several years to ensure that consumers get legitimate drugs when their prescriptions are filled. Today's "track and trace" methods use paper records to follow drug shipments from manufacturers to wholesalers and retail stores.

But paper records are not foolproof, Gottlieb said. By moving to electronic methods, including the use of RFID, the drug distribution system could be made safer against counterfeiting, he said.

"We think RFID is the most promising and achievable means to get to electronic track and trace or electronic pedigree by 2007," Gottlieb said. An "electronic pedigree" is a record of custody for a drug, which would include all transactions from its place of manufacture to where it is shipped, stored and sold. The FDA has been looking at RFID and other electronic technologies for the past three years, with a goal of having procedures in place by 2007.

In addition to using RFID, the FDA has eyed the use of special inks on individual pills or holographic images on medicine bottles, he said. "We've always said that we don't think there's a single magic bullet" to solve the problems and that several techniques will be needed to fight counterfeiting, Gottlieb said.

RFID technologies could even be used inside a consumer's medicine bottle or potentially on individual pills themselves, Gottlieb said.

Gottlieb said the FDA doesn't intend to use RFID tags to trace prescription drug use by individual consumers. "We are continuing to look at doing this without affecting consumer health or privacy," he said.

But consumer advocates remain wary.

"When I hear the FDA say, 'We're not interested in tracking individual consumers,' but then they want to put RFID tags on individual bottles, that's worrisome to me," said Katherine Albrecht, founder and director of Consumers Against Supermarket Privacy Invasion and Numbering, a Boston-based consumer rights group. Use of RFID chips is fine for supply chain bulk movement and tracking of merchandise, she said, as long as there are provisions to destroy the tags once the products reach consumers.

"I agree with the industry that there is a potential problem with counterfeiting" of prescription drugs, Albrecht said. But when RFID tagging reaches into consumers' homes, that's a problem, she said.

Cedric Laurant, a policy counsel at the Washington-based Electronic Privacy Information Center, said the concerns about RFID tags at the individual bottle or pill level relate to concerns about patients' privacy. How the information contained in the tag is used could be worrisome for consumers, Laurant said. Tags could include records of the transaction and other financial and personal data.

The FDA would have to show that there would be a "huge advantage" to fighting counterfeiting by tagging prescriptions at the bottle or pill level, Laurant said. "I don't exactly know if they could make the case," he said. "They would have the burden to prove it."

Instead, he said, as long as the tags are on large containers that don't identify consumers, "most privacy groups don't oppose the technology."

"They should be using a very strict rule that there be no RFID link on a specific product and the patient" who takes the medicine, he said.